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    • 专利摘要:
    system and method of sound reproduction to produce an audio signal as coming from a first direction with respect to a nominal position and a nominal orientation of a listener. a sound reproduction system for reproducing an audio signal as coming from a first direction with respect to a nominal position (211) and guidance from a listener is provided. the system comprises a first arrangement of the sound transducer (105) arranged to generate the sound that reaches the nominal position (211) from a first position corresponding to the first direction; and a second arrangement of the sound transducer (107) arranged to generate the sound that reaches the nominal position (211) from a corresponding second position in a different direction than the first direction. the arrangements can specifically be the speakers positioned in the given positions. a drive circuit (103) generates a first drive signal for the first sound transducer arrangement (105) and a second drive signal for the second sound transducer arrangement (107) of the audio signal. the first position and the second position are located in a sound confusion cone for the nominal position (211) and the nominal direction. more flexible speaker placement can be achieved.
    公开号:BR112013001414B1
    申请号:R112013001414-8
    申请日:2011-07-11
    公开日:2021-04-06
    发明作者:William John Lamb；Armin Gerhard Kohlrausch；Thomas Pieter Jan Peeters；Werner Paulus Josephus De Bruijn
    申请人:Koninklijke Philips N. V.；
    IPC主号:
    专利说明:

    [0001] The invention relates to a system and method for reproducing sound and in particular, but not exclusively, a surround sound reproduction system, for example, for home theater applications. BACKGROUND OF THE INVENTION
    [0002] Spatial sound systems that provide an improved spatial experience over traditional mono and stereo systems have become very popular. For example, surround systems with five or seven spatial channels (usually in addition to one or two channels of the Low Frequency Effect (LFE)) have become very popular for applications such as home theater systems.
    [0003] In many situations it is desirable to have small form factor speakers. However, the small size invariably affects the amplitude and low frequency response of sound reproduction. Thus, there is typically a balance between audio quality and the physical form factor for the speakers. In addition, spatial sound systems generally aggravate problems, as they tend to use only a large number of speakers, but also restrict the degree of freedom in their placement, as the position of the sound source is important for spatial perception .
    [0004] For example, surround sound systems, such as home theater systems, make use of many speakers to create immersive sound similar to that of a full-size cinema. For the most compelling and immersive sound experience, all speakers must be able to reproduce sound at full range. In addition, the speakers must be positioned in the appropriate positions to provide the desired spatial experience. This requires large speakers that are generally poor looking and difficult to position in a room. Many consumers find the directional speakers to be very confusing. It is therefore desirable to reduce the size of some or all of the speakers so that they are less visible and can be more easily incorporated into a room. In particular, the rear speakers are generally considered to be inconvenient in terms of size and positions. However, as the dimensions of the speakers are reduced, so is the performance of the low frequency and the Sound Pressure Level (SPL) achievable at a given frequency.
    [0005] To address such problems, most home theater systems employ a satellite subwoofer arrangement, where satellites are approximately reproducers of full-range sound, and the subwoofer reinforces only the lowest frequencies. Satellite subwoofer arrangements typically require the low pass frequency from the subwoofer to satellite speakers to be as low as possible. In a room, the location of the low frequency sound source (<120Hz) is difficult. This allows for almost free placement of the subwoofer within the room. If the low pass frequency is too high (above 120 Hz), the location indications for the subwoofer become apparent making the low frequency source easy to locate. For good sound quality and correct stereo image effects, satellites must be able to reproduce sound over almost the entire range. If satellites cannot cover the full audio range from 120 Hz to 20 kHz, the system is compromised. The designer can choose to either leave a gap in the frequency response of the 120 Hz system to the low cut of the satellite speakers or to increase the low pass frequency to the subwoofer. Both commitments reduce audio quality and the immersive listening experience.
    [0006] Thus, in many scenario balances between size and placement of speakers, on the one hand, and audio quality and spatial experience, on the other hand, they tend to be sub-ideal.
    [0007] Thus, an improved sound reproduction system would be advantageous and in particular a system that allows for high flexibility, high freedom in speaker placement, high audio quality, high sound pressure levels, an enhanced spatial experience and / or improved performance would be advantageous. SUMMARY OF THE INVENTION
    [0008] Certainly, the invention preferably seeks to mitigate, alleviate or eliminate one or more of the disadvantages mentioned above in isolation or in any combination.
    [0009] In accordance with an aspect of the invention, the sound reproduction system is provided to reproduce an audio signal as coming from a first direction with respect to a nominal position and the nominal orientation of a listener, the sound reproduction system comprising: a first arrangement of the sound transducer arranged to generate the sound that reaches the nominal position from a first position corresponding to the first direction; a second arrangement of the sound transducer arranged to generate the sound that reaches the nominal position from a second position corresponding to a different direction than that of the first direction; a drive circuit for generating a first drive signal for the first array of the sound transducer and a second drive signal for the second array of the sound transducer from the audio signal; wherein the first position and the second position are located in a sound confusion cone for the nominal position and the nominal direction.
    [0010] The invention can in many embodiments provide enhanced sound quality and a perception of the desired spatial sound source while providing additional flexibility in the location of the sound transducers. In particular, it can allow a plurality of sound transducers to combine with a sound transducer that dominates spatial perception while the other sound source (s) located in a different position significantly improves (m ) audio quality without significantly affecting spatial perception.
    [0011] The spatial perception of a listener in the nominal position and oriented in the nominal direction can be dominated by the sound from the first array of the sound transducer while the sound from the second array of the transducer can dominate or significantly impact the audio quality perceived by the listener .
    [0012] The invention can in many embodiments allow an improved balance between two or more of the audio quality, sound pressure levels, spatial perception, shape factor of the sound transducer layout and positioning.
    [0013] The approach can be applied in many different applications including, for example, sound reproduction for flat screens, such as televisions or flat panel monitors, computer speakers, car audio systems or home theater applications.
    [0014] A sound confusion cone is a cone in three-dimensional space in which Inter-Auditory Time Differences (ITD) and Inter-Auditory Level Differences (ILD) are close enough to not provide significantly different spatial indications to a user located at the source of the cone. The sound confusion cone represents a relative arrangement of the listening position (and orientation), the first position and the second position resulting in the ITD and ILD values for the first and the second position being substantially the same in the listening position (and orientation). Thus, the sound confusion cone for a specific arrangement can be defined for a given first listening and orienting position and position or equivalently for a given second listening and orienting position and position.
    [0015] The sound confusion cone can originate from the nominal position and comprise all spatial coordinates for which the ITD is less than 10% of the average sound path delay from the position to the nominal position, and the ILD is less than 10% of the average level in the nominal position. Specifically, the sound confusion cone can be a set of positions in which an audio path delay varies by no more than 50 μ sec and a loss of path varies by no more than 1 dB. In many embodiments, the sound confusion cone can extend up to 5 °, or in some cases up to 10 °, from an ideal cone for which the ILD and ITD are identical.
    [0016] Sound reproduction can, for example, be a surround sound system and the audio signal can be a spatial channel of a surround sound signal, such as a left or right channel signal, or a surround or channel signal left or right rear.
    [0017] According to an optional function of the invention, the drive circuit is arranged to generate the first drive signal to correspond to the higher frequency range of the audio signal than the second drive signal.
    [0018] This can provide particularly advantageous performance in many accomplishments. In particular, it can generally provide an advantageous arrangement where spatial perception is dominated by the first array of the transducer, which can be very small, while allowing the audio quality of the lower and medium frequency bands to be dominated by the second array of the transducer, which can have a form factor greater than the first transducer arrangement, and which can be more flexibly positioned. In fact, the spatial position can be determined by the first transducer arrangement thus allowing much more flexibility to position the possibly larger second transducer arrangement more discreetly. In fact, the approach can in many realizations create an illusion of full-range sound that originates from a small speaker, which alone cannot radiate low frequencies.
    [0019] According to an optional function of the invention, at least one of the first array of the sound transducer and the second array of the sound transducer comprises a speaker positioned in the first position and the second position respectively.
    [0020] This can allow a practical and low complexity implementation.
    [0021] According to an optional function of the invention, the sound reproduction system further comprises a third arrangement of the sound transducer arranged to generate the sound that reaches the nominal position from a third position corresponding to a different direction than the first direction ; and wherein the drive circuit is arranged to further generate a third drive signal for the third array of the audio signal's sound transducer.
    [0022] This can provide improved sound quality in many realizations, and can provide a high degree of flexibility in balancing sound transducer positions, audio quality and spatial experience.
    [0023] According to an optional function of the invention, the sound reproduction system is arranged to reproduce another audio signal as coming from a second direction with respect to the nominal position and the nominal orientation, and the sound reproduction system further comprises: a third arrangement of the sound transducer arranged to generate the sound that reaches the nominal position from a third position corresponding to the second direction; and wherein the drive circuit is arranged to generate the second drive signal by combining at least some signal components of the first audio signal and the second audio signal, and to generate a third drive signal for the third sound transducer a from the second audio signal.
    [0024] This can provide a high performance and particularly efficient approach for providing various spatial positions of the sound source. In fact, the second array of the sound transducer can be reused for different positions with each position requiring only an additional array of the transducer, which typically can be a small speaker with a higher frequency range with the lower frequency ranges. being provided by a single larger shared speaker located in a convenient position. The first and second audio signals can, for example, be audio signals other than a surround sound signal, such as a left front and rear sound signal, or a front and rear right sound signal.
    [0025] According to an optional function of the invention, the drive circuit is arranged to generate the first drive signal and the second drive signal so that the sound from the second transducer arrangement reaches the nominal position with a delay between 1 msec and 50 msec with respect to the sound from the first transducer arrangement.
    [0026] This can provide an enhanced dominance of the first transducer arrangement to provide spatial cues to the listener. The relative delays between the sound of the two sound transducer arrangements can be determined with respect to the audio signal. For example, they can be determined as the time difference in the nominal position of the signal components that are simultaneous in the audio signal. The approach can use the precedence effect to place more emphasis on spatial indications from the first array of the sound transducer with respect to spatial indications from the second array of the sound transducer.
    [0027] According to an optional function of the invention, the drive circuit is arranged to adjust at least one of a level difference and a time difference between the first drive signal and the second drive signal to compensate for a distance difference between a audio path from the first sound transducer array to the nominal position and an audio path from the second sound transducer array to the nominal position.
    [0028] This can provide improved performance and / or increased flexibility in positioning the sound transducer arrangements. For example, the interworking of the speakers can be located at different distances in the listening position without varying the distance resulting from unacceptable degradation.
    [0029] According to an optional function of the invention, the sound reproduction system further comprises an adjuster arranged to receive an input signal from a microphone positioned in the nominal position and to adjust at least one of the time difference and the level difference. in response to the microphone signal.
    [0030] This can provide a particularly advantageous fit resulting in improved performance in many scenarios.
    [0031] According to an optional function of the invention, the audio signal is a spatial channel of a surround sound signal, and the drive circuit is further arranged to generate the second drive signal in response to a second spatial channel of the sound signal. surround.
    [0032] This can provide particularly efficient surround sound reproduction. The approach may allow for a possibly higher speaker layout to provide audio quality at the lower and mid-range frequencies to be combined with small speakers at a higher frequency that provide the dominant spatial indications. The audio signal can, for example, be a left / right surround / rear channel with the second spatial channel being the corresponding front channel. Thus, the same second sound transducer arrangement can be shared for a surround / front and rear channel thereby reducing the number of separate sound transducers required.
    [0033] According to an optional function of the invention, the first arrangement of the sound transducer is arranged to radiate a directional sound that reaches the nominal position from the first direction through at least one reflection.
    [0034] This can provide a particularly advantageous configuration in many embodiments. In particular, it can provide additional flexibility in positioning the first arrangement of the sound transducer with respect to the position of the desired perceived sound source. In many embodiments it can allow both the first and the second arrangement of the sound transducer to be positioned in front of the user while providing a perception of sound that originates beside or behind the user.
    [0035] There were some achievements, the first and the second position have a horizontal difference of no more than 50 cm.
    [0036] According to an optional function of the invention, the first arrangement of the sound transducer is arranged to generate a virtual sound source in the first position; and the second arrangement of the sound transducer comprises a loudspeaker positioned in the second position.
    [0037] This can provide a particularly advantageous implementation in many realizations. In particular, it can provide additional flexibility in positioning the first arrangement of the sound transducer with respect to the position of the desired perceived sound source.
    [0038] According to an optional function of the invention, the second arrangement of the sound transducer is arranged to generate a virtual sound source in the second position; and the first arrangement of the sound transducer comprises a loudspeaker positioned in the first position.
    [0039] This can provide a particularly advantageous implementation in many realizations. In particular, it can provide additional flexibility in the positioning of the second array of the sound transducer with respect to the position of the desired perceived sound source.
    [0040] According to an optional function of the invention, the second position is such that an angle between a direction corresponding to the second position and the first direction is not less than 20 ° or, in fact, in some cases advantageously not more than 30 ° ° or 45 °.
    [0041] In some embodiments, the distance between the first position and the second position is not less than 1 meter or in some cases 2 or 3 meters.
    [0042] The approach can allow for very significant differences in the position of the different arrangements of the sound transducer. In fact, the approach may allow two speakers to be located away from each other while still combining to provide high audio quality and a single position of the perceived sound source. High flexibility in the positioning of the sound sources can be obtained and the approach can allow at least the second array of the sound transducer to be located discreetly at some distance from the direction of the desired spatial sound source perceived by a listener at the nominal position.
    [0043] According to one aspect of the invention, a method is provided for producing an audio signal as coming from a first direction with respect to a nominal position and a nominal orientation of a listener, the method comprising: generating a first trigger signal for a first array of the sound transducer and a second trigger signal for a second array of the sound transducer of the audio signal; the first arrangement of the sound transducer generating the sound that reaches the nominal position from a first position corresponding to the first direction; the second arrangement of the sound transducer generating the sound that reaches the nominal position from a corresponding second position in a different direction than the first direction; and where the first position and the second position are located in a sound confusion cone for the nominal position and the nominal direction.
    [0044] These and other aspects, functions and advantages of the invention will be evident and clarified with reference to the realization (s) described below. BRIEF DESCRIPTION OF THE DRAWINGS
    [0045] The realizations of the invention will be described, by way of example only, with reference to the drawings, in which: Figure 1 illustrates an example of elements of a sound reproduction system according to some embodiments of the invention; Figure 2 illustrates an example of a sound source configuration for a home theater system with surround sound; Figure 3 illustrates an example of a sound confusion cone for a listener; Figure 4 illustrates an example of elements of a sound reproduction system according to some embodiments of the invention; Figure 5 illustrates an example of elements of a sound reproduction system according to some embodiments of the invention; Figure 6 illustrates an example of elements of a sound reproduction system according to some embodiments of the invention; Figure 7 illustrates an example of elements of a sound reproduction system according to some embodiments of the invention; Figure 8 illustrates an example of a speaker configuration; Figure 9 illustrates an example of elements of a system for generating a virtual sound source; Figure 10 illustrates an example of elements of a sound reproduction system according to some embodiments of the invention; and Figure 11 illustrates an example of elements of a sound reproduction system according to some embodiments of the invention. DETAILED DESCRIPTION OF SOME ACCOMPLISHMENTS OF THE INVENTION
    [0046] The following description focuses on the realizations of the invention applicable to a surround sound reproduction system and in particular to a sound reproduction system for a home theater application. However, it will be noted that the invention is not limited to this application, but can be applied to many other sound reproduction systems and in many other usage scenarios.
    [0047] Figure 1 illustrates an example of elements of a sound reproduction system according to some embodiments of the invention. Figure 1 specifically illustrates elements associated with the reproduction of a single mono audio signal which, for example, can be a single spatial channel in a surround sound system. Thus, the sound reproduction system may also include other functionality for the reproduction of other channels of the surround sound system and specifically reproduce other spatial channels. It will also be noted that the functionality in figure 1 can still, as appropriate, be used to reproduce the sound for other channels.
    [0048] The system of figure 1 comprises an input circuit 101 that receives an audio signal. The audio signal can, for example, be a surround sound audio signal, which, for example, can comprise five or seven spatial channels with possibly one or two shared Low Frequency Effects (LFE) channels. The input circuit 101 can receive the audio input signal from any internal or external source.
    [0049] Input circuit 101 is coupled to a drive circuit 103 which in the example is a single channel drive circuit. Thus, the input circuit 101 provides an audio signal from one of the spatial channels of the surround sound to the drive circuit 103. For example, the elements of figure 1 may be arranged to reproduce, speak, a left surround channel (rear or side ) of the surround sound signal.
    [0050] The sound is reproduced by the first and second sound transducers which in the specific example are conventional speakers 105, 107. The drive circuit 103 is arranged to generate a first drive signal for the first speaker 105 and a second trigger for the second speaker of the audio signal. Thus, in the specific example, the left rear sound is reproduced by the combination of the two speakers 105, 107.
    [0051] In order to provide the appropriate spatial experience, it is important that the reproduced sound is perceived to originate from an appropriate direction at a given listening position.
    [0052] Figure 2 illustrates an example of a typical system configuration for a spatial surround sound reproduction system with five channels, such as a home theater system. The system comprises a central sound source 201 which provides a central front channel, a left front sound source 203 which provides a left front channel, a right front sound source 205 which provides a right front channel, a left rear sound source 207 that provides a left rear channel, and a right rear sound source 209 that provides a right rear channel. The five 201-209 sound sources together provide a spatial sound experience in a 211 listening position and allow a listener in this location to test a surrounding and immersive sound experience. Thus, typical surround sound systems are configured to provide an appropriate spatial experience for a listener positioned in a nominal or reference position and having a nominal or reference orientation, that is, in the configuration in figure 2 it is assumed that the listener facing the sound source of the central front channel 201.
    [0053] It will be noted that the nominal (or reference) position does not depend on any actual listener present or on listeners present in other positions. In addition, the nominal position and orientation are a function of the system / configuration. Nominal position and orientation can specifically represent the position and orientation for which the spatial experience has been optimized.
    [0054] The requirement for loudspeakers to be located, in particular, next to or behind the listening position is typically considered disadvantageous, as it not only requires additional speakers to be located in the inconvenient positions, but also requires that they be connected to the source drive, as typically a home theater power amplifier. In a typical system configuration, cables are required to be operated from the surround sound sources to an amplifier unit that is typically located close to the front sound sources. In addition, in order to achieve the desired audio quality a reasonably large form factor it is typically necessary for all speakers to function as sound sources. In order to alleviate or mitigate the perceived disadvantages, it is desirable to have as much freedom as possible in the positioning of the speakers that provide the sound reproduction. However, this desire is typically opposed by the requirement that a specific spatial experiment must be provided at the nominal position.
    [0055] In the approach of figure 1, the high flexibility in positioning the speakers 105, 107 is obtained by allowing the two speakers 105, 107 to be positioned far away while ensuring that the spatial perception is predominantly generated by the first speaker 105. Specifically, the first speaker 105 is positioned so that its sound reaches the nominal position of a desired direction associated with the space channel. Specifically, the first speaker 105 is positioned so that its sound reaches the nominal listening position from a corresponding direction in a desired position for the left surround sound source.
    [0056] The second speaker 107 is positioned in a different position and is not restricted to a position where the sound reaches the nominal position from the direction of the spatial position of the desired sound source. Preferably, one approach allows the second speaker 107 to be positioned more freely. This can be particularly advantageous, for example, if the second speaker is substantially larger than the first speaker 105, as it can allow the second speaker 107 to be positioned more discreetly.
    [0057] However, none of the first and second loudspeakers 105, 107 are positioned completely freely, but are preferably restricted to positions that with respect to each other in a confusing sound cone for the nominal position and the nominal direction.
    [0058] The human auditory system makes use of Inter-auditory Time Differences (ITD), Inter-Auditory Level Differences (ILD) and spectral indications to locate sound sources. Spectral indications are usually evident at high frequencies where the shape of the outer ear begins to influence the dispersion of sound. At lower frequencies, typically below 3 kHz, ITDs and ILDs are the main localization modalities. ITD and ILD are the result of the different acoustic passages taken by the sound to reach any ear. At low frequencies (20 to 500 Hz) the sound intensity is approximately equal in both ears and the ITD is the dominant localization modality. ITD is the difference in the periods of arrival of a sound source in each ear, typically due to the difference in the length of the passage. As the frequency increases, the head begins to act as an acoustic shadow and the intensity of the sound in the different parts of the head is dependent on the location of the source. This acoustic shadow effect gives rise to differences in intensity in the ears. Sound sources located in different positions relative to the head result in a combination of the dependent ITD and ILD angle indications. Due to the approximate symmetry of the head, for most source directions, the ITD and ILD of the sound source are not unique to this specific elevation and angular azimuth. Without additional spectral information, it is difficult for the listener to distinguish whether the source is coming from either location with the same ITD and ILD. The location of the points for which a sound source has the same ITD and ILD is known as the confusion cone, as illustrated by the example in figure 3.
    [0059] The sound confusion cone then represents a relative arrangement of the listening position (and orientation), and the positions of the sound source that result in the ITD and ILD values for the first and second positions being substantially the same for a nominal user in the listening position (and orientation). It will be noted that the cone of confusion is not only defined by the listening position (and orientation), but by the listening position (and orientation) and at least one point in the confusion cone. Thus, the confusion cone defines a set of relative positions for the sound sources so that if a position of the sound source is determined (with the listening and orientation position), the corresponding sound confusion cone for the values of ITD and ILD is substantially the same as it is also defined.
    [0060] In many cases the cone of confusion can be an impediment, especially with the headset, where the problem of front-to-back reversal is well known. However, in the system in figure 1, the phenomenon is actively used to position two speakers interacting in different positions while still allowing them to be perceived as coming from a single position of the desired sound source. Thus, the system in figure 1 can exploit the confusion cone to create strong and robust auditory illusions.
    [0061] In fact, since the auditory system has difficulty in interpreting the location of a sound source in the confusion cone, this effect is actively exploited to hide the location of a speaker. For example, if a low frequency speaker is positioned in one location and a second high frequency speaker (tweeter) is positioned in another position in the confusion cone created by the position of the low frequency speaker and the position and listening orientation, an illusion can be created so that the full-range sound completely enters the tweeter.
    [0062] Specifically, the tweeter can play ο high-frequency content that is then filtered in its acoustic passage through the listener's head and outside ear. This gives a unique spectral signature to the tweeter's location, making the tweeter easy to locate. At low frequencies the ITD and ILDs are consistent with any position in the confusion cone. The location of the low frequency speaker does not transmit significant spectral formation to the low frequency signal, and is therefore difficult to locate precisely in the confusion cone. The lack of a uniquely identifiable location of the speaker with the lowest frequency allows the auditory system to link the two sound sources, creating a full-range auditory image at the location of the tweeter. This auditory illusion is very strong, as the location indications are completely consistent with the target location of the sound source (the location of the tweeter).
    [0063] Thus, the sound confusion cone is an example that can be given by the position of the low frequency speaker and the listening position and orientation, thus defining a set of appropriate positions for the high frequency speaker. Equivalently, the sound confusion cone can be given by the position of the high frequency speaker and the position of listening and orientation, thus defining a set of positions appropriate for the low frequency speaker.
    [0064] The sound confusion cone can then be considered to correspond to these relative positions in space so that the difference in time and the difference in level between the listener's ears (nominal) are low enough not to provide substantially different spatial indications in the position hearing. Specifically, the sound confusion cone can typically correspond to spatial positions in which the ITD varies no more than 50 microseconds and the ILD no more than 2 dB. Thus, the sound confusion cone can define, specifically in some embodiments, a set of positions in which an audio path delay varies by no more than 50 microseconds and a difference in path loss varies by no more than 1 dB. In some embodiments, the confusion cone may comprise the spatial positions in which the ITD is less than 10% of the average delay of the sound path from the positions to the nominal listening position and in which the ILD is less than 10% of the level in the nominal position.
    [0065] Such requirements will result in the characteristics of ILD and ITD being perceived to correspond to the same position. In this case, the spatial position of the combined sound source will be perceived to correspond to the position indicated by the frequency modification of the high frequency sound by the human ear. Thus, the spatial position will be perceived to be the tweeter.
    [0066] In the example, the first speaker 105 is a high frequency speaker, like a tweeter, and the second speaker 107 is a low frequency speaker. Certainly, the generation of the first drive signal for the first speaker 105 by the drive circuit 103 typically includes high-pass filtering of the audio input signal and the generation of the second drive signal for the second speaker 107 by the drive circuit 103 typically includes low-pass filtering of the audio input signal. As illustrated in figure 4, the drive circuit 103 can specifically comprise a high pass filter and a low pass filter (with, for example, the proper amplification functionality which for clarity and brevity is not explicitly discussed here).
    [0067] Thus, in the example, drive circuit 103 generates the first drive signal to correspond to a higher frequency range of the audio signal than the second drive signal. In some embodiments, the two speakers 105, 107 can cover a separate part of the spectrum and, in fact, can together cover the entire audio track. In other embodiments, other speakers can, for example, cover other frequency ranges of the audio signal. For example, a subwoofer can support frequencies up to, 120 Hz, the second speaker 107 can span the frequency range from 120 Hz to 500 Hz, a third speaker can span the frequency range from 500 Hz to 1.5 kHz and the first speaker 105 can span the frequency range of 1.5 kHz up to, for example, 20 kHz.
    [0068] In many embodiments, a cutoff frequency of 3-dB lower than the first trigger signal cannot advantageously be less than 400 Hz, 600 Hz, 800 Hz, 1 kHz or even 2 kHz. The higher the selected frequency, the smaller and more discreet the first 105 speaker will be.
    [0069] In many embodiments, a cutoff frequency of 3-dB higher than the second drive signal cannot advantageously be less than 400 Hz, 600 Hz, 800 Hz, 1 kHz or even 2 kHz. The higher the selected frequency, the more frequency range will be covered by the second speaker and consequently the smaller and more discreet the first speaker 105 will be.
    [0070] The lower 3-dB cutoff frequency of the first trigger signal and the higher 3-dB cutoff frequency of the second trigger signal may differ substantially from each other, and may, for example, differ by not less than 200 Hz , 400 Hz, 600 Hz, 800 Hz or even 1 kHz.
    [0071] In some embodiments, a frequency passes low between the first and second trigger signals can be in the range of 200 Hz to 2 kHz, and generally advantageously in the range of 600 Hz to 1.5 kHz. The low pass frequency can be determined as the frequency at which the attenuation of the two trigger signals with respect to the audio input signal is the same.
    [0072] Such low-pass and cut-off frequencies can, in particular, allow high-frequency drivers of the small form factor to provide the dominant spatial indications. In particular, an appropriate selection of the frequency ranges for the different speakers can ensure that the spatial indications provided from the second speaker 107 are restricted to the indications of ITD and ILD. Certainly, the design can guarantee that the second speaker 107 provides only spatial indications which are also consistent with the spatial indications for the position of the first speaker 105.
    [0073] In fact, in many conventional satellite subwoofer arrangements, the low pass frequency is chosen to suit the frequency response of the speakers. In the approach described, the strength of the effect at the listening position is independent of the low pass frequency as long as this frequency remains below a threshold value. This limit value is a function of the Head-Related Transfer Function (HRTF), and is the point at which the spectral modification of the acoustic passage due to the dispersion of the external ears begins to contribute significant location indications. The limit value for an individual listener is a function of their anatomy and varies over a population of users. However, a nominal limit value can be selected covering almost the entire population. Low pass frequencies as high as 800 Hz have been shown to perform very well, and in fact, high low pass frequencies are possible in many performances.
    [0074] In the example, the first and second physical speakers 105, 107 are positioned directly in the confusion cone with the first speaker 105 being positioned in a desired position for the perception of the spatial sound source. For the left surround channel the first speaker 105 can, for example, be positioned in the sound confusion cone at the left rear of the listener. The second speaker 107 can be positioned at a significant distance and in a significantly different direction than that of the first speaker 105. For example, the second speaker 107 may be positioned in front of the listening position. This can in many embodiments be particularly advantageous, as the second speaker 107, for example, can be positioned close to the surround sound speakers for other channels and specifically close to the speakers to feature the front side channels. However, the second speaker 107 is positioned so that it is in the same confusing sound cone as the first speaker 105. As a consequence, the sound reproduced from both speakers 105, 107 will be perceived to arrive at the listening position of the first speaker 105, that is, from the left rear direction.
    [0075] The first and second loudspeakers 105, 107 can be positioned in positions that are not less than 1 meter, 2 meters or 3 meters apart from each other. Loudspeakers 105, 107 can be positioned in completely different directions with respect to the nominal listening position. In some embodiments the direction of the two speakers can vary by no less than 20 ° and, in fact, in some embodiments by no less than 30, 45 ° or even 60 °.
    [0076] The approach described then uses processing and a speaker layout scheme that allows for the reduction in size, for example, of the surround back speakers to the extreme without degrading the subjective audio quality and the spatial performance in the listening position. Such size reductions allow the cost and power consumption of the speaker unit to be significantly reduced. Reducing the size of the rear speakers is very desirable for the lifestyle ranges of home theater systems. Reducing power consumption is a permissive step for battery-powered wireless operation of surround sound speakers.
    [0077] The reduction in size is achieved through the use of psychoacoustically triggered signal processing and several loudspeaker units judiciously positioned with respect to the listening position to ensure location indications consistent with the source's target location.
    [0078] The approach provides a very robust method for creating a psychoacoustic illusion. This type of auditory illusion is also independent of the high-frequency acoustic transfer function of the individual listener. This allows the illusion to be effective for almost all users with normal hearing.
    [0079] An added advantage of processing is the simplicity of the necessary filtering operations, which can be performed on both the digital and analog circuit.
    [0080] This illusion is also not restricted to sound sources in the horizontal plane. High frequency sources, or indeed low frequency sources, can also be placed above or below the listener. The illusion of full-range audio at the location of the high frequency source will be robust as long as the low frequency source is in the same cone of confusion.
    [0081] However, although it is not necessary for the sound sources to remain in the horizontal plane, in some embodiments it may be advantageous that they do not deviate significantly from it. In many embodiments, at least the vertical difference between the position of the first and second sound transducers in the confusion cone cannot be more than 50 cm or even 25 cm. This can have advantages in terms of the size of the listening point. In fact, if both speakers are located in the horizontal plane and equidistant from the listener, the effect can be shown to be robust for all displacements along the inter-auditory axis.
    [0082] In the example in figure 1, two loudspeakers 105, 107 were used to present the audio input signal to the drive circuit 103. However, in other embodiments more than two loudspeakers can be used. For example, instead of a single low / mid range speaker cover, for example, the frequency range up to 1 kHz, this frequency range can be covered by a low range speaker and a loudspeaker mid-range. In this case, the extra speaker (s) need not be placed with any other speakers, but can, for example, be positioned in other positions. As long as these positions are in the confusion cone (and cover the frequency ranges below the ear-dependent filtering), the additional speaker will not provide new spatial indications to the user and the total reproduced sound will be perceived to originate from a single source.
    [0083] In the example in figure 1, the audio signal being processed by the speakers 105, 107 is a spatial channel of a surround sound signal. Specifically, the space channel can be the left surround channel. In some embodiments, the second speaker 107 can be used to process two (or more) of the space channels. For example, second speaker 107 may be located on the left front of the listening position and thus in a position where it is suitable for processing the front left space channel.
    [0084] Figure 5 illustrates an example of such an embodiment. In the example, the second speaker 107 is also used as the front left speaker 203. In the example, this is achieved by the drive circuit 103 comprising a combiner that combines the left front channel audio signal with the audio signal low pass filter for the left surround channel. Thus, the second trigger signal is generated from the audio signals from both spatial channels. The drive circuit 103 can specifically generate the second drive signal as the weighted sum of the audio signals from the two channels (typically following the filtering of at least one of the audio signals).
    [0085] The approach can certainly be used similarly, for example, by the surround back channel. As a specific example, figure 5 illustrates a surround sound system in which two full-range speakers reproduce the front left and right channels. The two high-frequency transducers are placed behind the listener at the angles facing the angled locations of the full-range speakers, placing them in the same confusion cone as the front speakers. The left and right surround channels are divided into a low frequency part and a high frequency part. The high frequencies are reproduced by the high frequency speakers, while the low frequency part is added to the full range channels in front of the listener. The effect should produce a very remarkable impression of a full-range sound that comes from the rear high-frequency speakers. This system allows very compact surround back speakers. Since high-frequency speakers draw very little power, they could be connected by battery and receive music signals from the wireless surround receiver. In addition, the two full-range front speakers double the processing of both the front side channels and the lower frequency portion of the surround channels. Thus, the system can also make use of the types of speakers that are already used in home theater systems for the front channels without further modification.
    [0086] It will be noted that the approach is not limited to creating the illusion of the rear channels. For example, the system can be inverted so that the full-range speaker is behind the listener and the high-frequency source is placed in front of the user. This is of particular use for devices that, due to form factor restrictions, do not allow the integration of full-range speakers, while the location of the full-range sound in the device's location is desirable. Examples include televisions and flat-panel computer monitors.
    [0087] In some embodiments, the loudspeakers 105, 107 that process the audio signal can be positioned at varying distances from the listening position, but still in the confusion cone. In fact, it should be noted that the confusion cone represents a three-dimensional object / surface and not just a ring. In fact, it is not necessary for the speakers to be located equidistant from the listener. If the speakers are located at varying distances from the listening position, delay compensation can be applied to ensure a constant arrival time for all sound components in the listener's position.
    [0088] Specifically, the drive circuit 103 may comprise the functionality to adjust the level difference and / or the time difference between the first drive signal and the second drive signal. For example, Figure 6 illustrates how drive circuit 103 can include a delay 601 that increases the delay between the second drive signal and the audio input signal with respect to the delay between the first drive signal and the input signal. of audio. The delay is defined to compensate for a greater distance to the first speaker 105 from the listening position than to the second speaker 107 in the listening position. Thus, the delay compensates for the difference in propagation delays in the audio paths of the first and second loudspeakers 105, 107 respectively at the nominal listening position.
    [0089] Thus, in such systems the difference in inter-auditory time and / or the difference in inter-auditory level that provides spatial indications is managed by the placement of speakers 105, 107 in the sound confusion cone where the absolute difference (or average) of time or level difference between speakers 105, 107 (instead of between a user's ears) is controlled by the processing of trigger signals.
    [0090] The adjustment of any time difference or the difference in speaker level (or both) can in some embodiments be automatically adapted to the specific characteristics of the configuration. For example, a microphone located in the listening position can be used to record the acoustic output of the multichannel system and to calculate the distances relative to the speakers. This distance can be covered in a sample-based delay line and used to compensate for the periods of emission of the respective low and high frequency signals to ensure consistency of the location indications. The microphone can also be used to adjust the properties of the audio system such as the frequency response and amplitude of the individual sound sources to optimize the listening experience.
    [0091] In some embodiments, the drive circuit may be arranged to generate the first drive signal and the second drive signal so that the sound from the second speaker 107 reaches the nominal position with a delay between 1 msec and 50 msec with respect to to the sound of the first speaker 105. Thus, the simultaneous audio components of the audio input signal will result in the sound at the listening position that is delayed from the second speaker 107 with respect to the first speaker.
    [0092] Such an approach can exploit the psychoacoustic phenomenon known as the "precedence effect" (also referred to as the "Haas effect" or the "law of the first wavefront"). This phenomenon indicates that when the same sound signal is received from the two sources in different positions and with a sufficiently short delay, the sound is perceived to come only from the direction of the sound source that is ahead, that is, from of the first sign of arrival. Thus, the psychoacoustic phenomenon refers to the fact that the human brain derives most of the spatial indications from the first signal components received. In fact, it has been observed that such an effect is still achieved when applied at different frequency ranges of an audio signal.
    [0093] Through the use of the precedence effect it is possible to create auditory illusions that improve the perceived audio quality and the bandwidth of the satellite speakers with a restricted bandwidth. The precedence effect is a psychoacoustic phenomenon based on the temporal weight in the auditory system. For localization purposes, the auditory system weighs the first sound that reaches the ears with the most importance. If two speakers placed in different locations emit the same signal, the speaker whose signal reaches the listener's ears first will be perceived as the sole source of the sound source. This is valid under the conditions that the delay between the sounds that reach the ears is above 1 ms and below a limit value of 5 - 50 ms, depending on the type of stimulus. As mentioned, the precedence effect has also been shown to be partially effective when the sound sources are divided into different frequency ranges and reproduced by the different speakers.
    [0094] The precedence effect can then be used to further enhance the spatial perception of a single source positioned at the position of the first speaker 105. In fact, where it just depends on the precedence effect it can be sub-ideal in many scenarios (for example, the illusion is not completely effective and may result in the distorted stereophonic image), the combination of the precedence effect and the use of the confusion cone provide a substantially improved illusion.
    [0095] Thus, the precedence effect can be used to further improve the robustness of the illusion, for example, in relation to the small movements and rotations of the listeners' head. This is achieved by adding a delay on the low frequency channel. The delay is chosen so that the low frequency information from the low frequency channel reaches the listening position approximately 1 to τ ms after the high frequency information. The delay time i can vary from 5 to 50 ms depending on the audio signal, and can be chosen through an optimization based on information such as system, low pass frequencies, acoustic environment and input signal.
    [0096] The approach can, for example, be implemented by the system of figure 6 which determines an adequate delay necessary for the difference in the propagation time to be compensated and then adjust the delay 601 to, for example, 10 msec more than the calculated value.
    [0097] In some embodiments, the approach can be used to provide an illusion of full-range sources at various locations. This can be specifically achieved using a single low frequency transducer and a plurality of high frequency units. An example of such an approach is shown in figure 7. In the example, each channel of a multichannel channel N (Xi (t), X2 (t), X3 (t), ... Xn (t)) is divided into two regions frequency using a low-pass network. Each of the resulting high-frequency signals is sent directly to the high-frequency N-speakers 701 located in the confusion cone 703. The low-frequency signals from each channel are added and transmitted to the low-frequency speaker 705, also located in the confusion cone. In the example, a set of delays 707 is included to provide compensation for the difference in the length of the passage and / or to improve the precedence effect for each channel.
    [0098] Thus, in the example in figure 7, the system is arranged to reproduce at least one additional sound signal that reaches the nominal listening position from a different direction than for the first audio speaker. This is achieved by adding another speaker positioned in the different direction and generating a trigger signal for this audio speaker from the additional audio signal. In addition, the second drive signal for the second speaker 705 is generated by combining the two audio signals. The combination can specifically be a weighted sum where the weight can reflect the desired volume relative to the two signals.
    [0099] In the previous examples, the sound was provided by the physical speakers positioned directly at the appropriate positions of the sound cone. However, in other embodiments the sound may not be provided by the physical speakers in such positions, but it may still be provided by the virtual sound sources in the confusion cone. So, instead of using the physical speakers in the confusion cone, the approach can use sound transducer arrangements that can provide a virtual sound source positioned in the confusion cone. The sound transducer arrangements may, for example, be a physical speaker, but may, for example, alternatively or additionally be a transducer array, a directional speaker, a modulated ultrasound transducer, etc.
    [0100] As an example, a conventional full-range speaker positioned in the confusion cone can be used as the second speaker 107 where the first speaker 105 is replaced by a sound transducer arrangement that is arranged to radiate a sound directional to reach the nominal position from the first direction through at least one reflection. Thus, in the example, the high frequency source is created using a beam of directional sound that, for example, when reflecting off a wall will be dispersed in the room. In this case, a listener would perceive the reflection point on the wall to be the source of the sound source. In this way, the sound transducer arrangement can be arranged to radiate a highly directional sound beam so that it touches the wall at a point that is in the confusion cone for the nominal listening and orientation position. Such audio radiation can, for example, be perceived by a large array of high frequency units and beam formation, combined with an appropriate sound beam formation algorithm.
    [0101] As another example, the beam can be generated using an ultrasonic or parametric speaker to radiate a modulated ultrasonic signal towards the reflection point on the wall. This can project a highly directional, high-intensity ultrasound beam modulated by high-frequency audio. As ultrasound propagates through the air, the audio signal is demodulated by non-linearities to form a highly directional sound beam. When this sound beam encounters an obstacle, such as a wall or large object, the sound of the audio frequency is reflected over a wide range of angles thus providing the perception of a sound source located at the point of incidence.
    [0102] It will be noted that in some embodiments, it can be advantageous for the high frequency transducer to be a virtual sound source where the low frequency transducer is a physical speaker located in the confusion cone. For example, when generating a rear channel using the approach described, this can allow all sound transducers to be positioned in front of the user while still providing a spatial perception of sound that reaches the listener from behind. Thus, in some embodiments, the high-frequency physical speakers of the original example can be replaced by virtual sound sources. An advantage of the principle of this approach is that the rear speakers no longer need to be physically present.
    [0103] In other embodiments, the second speaker 107 can be replaced by a virtual sound source while the first speaker 105 can possibly be maintained as a physical speaker positioned in the confusion cone. Thus, in some embodiments, the low frequency speaker can be replaced by virtual sources, for example, using techniques such as crosstalk cancellation or a stereo dipole approach. An advantage of the principle of this approach is that low frequency virtual sources can be relatively easy to create at any angular location in the frontal plane, and thus restrictions on the location of high frequency transducers can be relaxed according to the low frequency source. virtual sound can be relatively easily positioned whenever the confusion cone for the position of the specific high frequency transducer ends. In other words; given the arbitrary location of a frequency transducer, a complementary low-frequency virtual source can be synthesized in the appropriate positions given by the sound confusion cone that arises from the selected location. The location of the speakers and the listener is preferably known before the virtual sources are located in the appropriate confusion cone. The methods of determining the relative locations of the speakers are well known and it will be appreciated that any suitable method for doing so can be used.
    [0104] It will be observed that the different techniques and algorithms exist to generate the virtual sound sources (which can be considered a sound source that is not physically present in the location that the listener perceives). The creation of virtual sources is achieved by producing an audio signal in the listener's ears with any exact or approximate location indications corresponding to the target location.
    [0105] In the following, a specific example of how virtual sound sources can be generated will be described.
    [0106] The acoustic passages considered by a sound transmitted from a pair of speakers to reach the ears are shown schematically in figure 8. The acoustic passages create spectral filtering of ITD and ILDs specific to the locations of the speakers making the speakers easily findable by the listener. Each acoustic passage can be represented as a HaL transfer function, where the first subscript refers to the angular location of the speaker and the second subscript to the ear. Ear signals can be expressed mathematically using the matrix equation
    [0107] Based on this equation, it is clear that applying an inverse operation of the M-1 matrix to the signals before transmission through the speakers is possible to eliminate the crosstalk effects.
    [0108] In this paradigm the left ear receives signals from the left speaker, and the right ear receives signals from the right speaker only. By incorporating location indications into L and R speaker signals, using any modeled transfer functions or HyL and Hyx measurements, it is possible to create virtual sound sources at any location γ around the listeners' head as shown in Figure 9:
    [0109] It is generally desirable to put the physical speakers together. This makes the transfer matrix M less complex allowing for an ideal inversion. In fact, if the speakers are very close, the stereo dipole techniques can be used to approximate the transfer matrix and its inversion, allowing very simple filtering operations. An advantage of this approach is less coloring and a reasonably robust hearing illusion. Approximate processing schemes such as the stereo dipole approach typically restrict virtual sources to the frontal plane.
    [0110] Under ideal conditions, crosstalk cancellation results in the perfect perception of virtual sources since the auditory indications are completely consistent with the target location of the targeted source. Due to imperfections in the transfer function measurements, cutting during matrix inversion, loss of dynamic range and power limitations of the amplifier and speakers, the strength of the illusions may be reduced, or become inefficient. For example, the transfer matrix M can generally be poorly suited to inversion by being 'poorly conditioned'. This implies that small disturbances in the measured or modeled transfer function can result in large errors in the inverted transfer matrix Μ-1. Poor conditioning makes crosstalk cancellation unstable with small head movements, especially at low frequencies. Another by-product of this poorly conditioned system is the significant coloration of the audio. This is particularly evident to listeners not positioned precisely at the listening point.
    [0111] The illusion is dependent on the precision of the M transfer matrix. The matrix is constructed from the modulated or measured transfer functions described in figure 8. These transfer functions are not only a function of the location of the speakers, but are also of the anatomy of the speaker. user and are unique to each individual. As small imperfections in the transfer functions can create large errors in the crosstalk filters, the ideally accurate filters for each individual would be measured and used for the cancellation network. For economic viability a generic set of transfer functions can be chosen to provide good compatibility for the majority of the population, even if not ideal for many users is general.
    [0112] The crosstalk is removed by transmitting additional sound to cancel out unwanted acoustic information. This additional sound can be considered 'wasted' energy, as it does not contribute to the audio heard by the listener. In some cases, the audio signal in the ears is 30 dB less than the transmitted audio signal. The effect of this 'wasted' energy is to reduce the dynamic range of the system and place high demands on the speakers and amplifiers.
    [0113] The generation of the virtual font can be complicated and it can be difficult to obtain robust and convincing results. Using the concept of the confusion cone in parallel with virtual speaker technology, physical speakers can reinforce the necessary location indications over certain frequency ranges, significantly strengthening auditory illusions and or improving energy efficiency. These two modalities are, in reality, highly complementary; the concept of the cone of confusion allows very convincing auditory illusions to be created while the cancellation of the crosstalk and the generation of the virtual source relaxes the strict geometric demands of the cone of confusion.
    [0114] As previously mentioned, this complementary nature can be exploited to be both the high frequency speaker and the low frequency speaker by the virtual sound sources.
    [0115] Figure 10 illustrates an example where the high frequency physical sources for the rear speakers are replaced by virtual sources. The most obvious advantage of this approach is that the user no longer needs to position the additional speakers at the back. The illusion is dependent on the correct crosstalk cancellation at high frequencies. The system will only be effective if each virtual source is correctly located in the same confusion cone as the low-frequency physical speaker, which limits the range of available positions of the virtual source.
    [0116] Compared to a full-range crosstalk cancellation system, this approach represents significant savings in electricity by eliminating low-frequency crosstalk cancellation. This represents a potential savings of up to 30 dB in loudspeaker and amplifier height in low frequency reproduction, allowing the use of cheaper drive units and amplifiers.
    [0117] Figure 11 illustrates an example in which the low-frequency physical speakers of the rear channels are replaced by virtual sources. The most significant advantage of this approach is that the source of high frequencies can be placed arbitrarily around the listener. The use of virtual low-frequency sources relaxes all restrictions on speaker placement for the confusion cone configuration as complementary low-frequency sources can be generated at any necessary angle.
    [0118] All necessary low-frequency virtual sources can be created by a compact cabinet containing at least two low-frequency transducers. Greater efficiency and control over virtual sources can be achieved by increasing the number of low frequency speakers. These transducers must be able to emit enough acoustics to provide sufficient crosstalk cancellation. Virtual low frequency sources can be created using very simple stereo dipole processing as low frequency sources only needed are generated in the frontal plane. As long as the ITD and ILD indications of the low frequency sources are consistent with the high frequency units, the illusion will be very robust.
    [0119] Because the high-frequency indications are provided by the actual sources, they are not affected by differences in individual anatomical functions. This is a significant advantage over standard crosstalk cancellation schemes, which require individualized crosstalk filters to be really effective. At low frequencies, below the low pass frequency (eg 800 Hz), anatomical spectral filtering provides less significant auditory cues meaning that individual-specific filters are not needed for this approach.
    [0120] It will be noted that the above description for clarification described embodiments of the invention with reference to the different functional circuits, units and processors. However, it will be evident that any suitable distribution of functionality between different functional circuits, units or processors can be used without prejudice to the invention. For example, the illustrated functionality to be performed by separate processors or controllers can be performed by the same processor or controllers. Thus, references to specific functional units or functional circuits are only to be seen as references to the appropriate means to provide the described functionality rather than indicative of a strict logical or physical structure or organization.
    [0121] The invention can be implemented in any suitable way including hardware, software, firmware or any combination thereof. The invention can optionally be implemented at least partially as computer software that operates on one or more data processors and / or digital signal processors. The elements and components of an embodiment of the invention can be physically, functionally and logically implemented in any suitable way, in fact, the functionality can be implemented in a single unit, in a plurality of units or as part of other functional units. In this way, the invention can be implemented in a single unit or it can be physically and functionally distributed among the different units, circuits and processors.
    [0122] Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form defined here. In addition, the scope of the present invention is limited only by the appended claims. In addition, although the function may appear to be described in connection with the particular embodiments, a person skilled in the art would recognize that various functions of the described embodiments can be combined according to the invention. In the claims, the term "comprising" does not exclude the presence of other elements or steps.
    [0123] In addition, although individually listed, a plurality of means, elements, circuits or steps of the method can be implemented, for example, by a single circuit, unit or processor. In addition, although individual functions can be included in different claims, they can possibly be advantageously combined, and inclusion in different claims does not imply that a combination of functions is not feasible and / or advantageous. In addition, the inclusion of a function in one category according to the claims does not imply a limitation to this category, but it still indicates that the function is equally applicable to other categories of the claim as appropriate. Furthermore, the order of functions in the claims does not imply any specific order in which the functions are to be operated and in particular the order of individual steps in a method claim does not imply that the steps are to be performed in that order. Preferably, the steps can be carried out in any suitable order. In addition, singular references do not exclude a plurality. Thus, references to "one", "one", "first", "second" etc. they do not exclude a plurality. The reference signs in the claims are provided merely as an illustrative example and should not be construed as limiting the scope of the claims in any way.
    权利要求:
    Claims (13)
    [0001]
    SOUND REPRODUCTION SYSTEM FOR REPRODUCING AN AUDIO SIGNAL FROM A FIRST DIRECTION WITH REGARD TO A NOMINAL POSITION (211) AND A NOMINAL GUIDANCE FROM A LISTENER, the sound reproduction system comprising: a first arrangement of the sound transducer (105) arranged to generate the sound that reaches the nominal position (211) from a first position corresponding to the first direction; a second arrangement of the sound transducer (107) arranged to generate the sound that reaches the nominal position (211) from a second position corresponding to a different direction than that of the first direction; a drive circuit (103) for generating a first drive signal for the first sound transducer arrangement (105) and a second drive signal for the second sound transducer arrangement (107) of the audio signal; on what the first position and the second position are located in the same sound confusion cone for the nominal position (211) and the nominal direction, said reproduction system is characterized by the drive circuit (103) being arranged to generate the first signal drive to match the higher frequency range of the audio signal than the second drive signal; and at least one of the first sound transducer arrangement (105) and the second sound transducer arrangement (107) comprises a speaker positioned in the first position and the second position respectively.
    [0002]
    SOUND REPRODUCTION SYSTEM, according to claim 1, characterized in that it additionally comprises a third arrangement of the sound transducer arranged to generate the sound that reaches the nominal position (211) from a third position corresponding to a different direction than from the first direction; and wherein the drive circuit (103) is arranged to further generate a third drive signal for the third arrangement of the sound transducer of the audio signal.
    [0003]
    SOUND REPRODUCTION SYSTEM, according to claim 1, being further arranged to reproduce another audio signal as coming from a second direction with respect to the nominal position (211) and the nominal orientation, and the sound reproduction system characterized by additionally understand: a third arrangement of the sound transducer arranged to generate the sound that reaches the nominal position from a third position corresponding to the second direction; and wherein the drive circuit (103) is arranged to generate the second drive signal by combining at least some signal components of the first audio signal and the second audio signal, and to generate a third drive signal for the third transducer of the second audio signal.
    [0004]
    SOUND REPRODUCTION SYSTEM, according to claim 1, characterized in that the drive circuit (103) is arranged to generate the first drive signal and the second drive signal so that the sound of the second sound transducer arrangement (107 ) reaches the nominal position with a delay between 1 msec and 50 msec with respect to the sound of the first sound transducer arrangement (105).
    [0005]
    SOUND REPRODUCTION SYSTEM, according to claim 1, characterized in that the drive circuit (103) is arranged to adjust at least one of a level difference and a time difference between the first trigger signal and the second trigger signal to compensate for a difference in distance between an audio path from the first sound transducer arrangement (105) to the nominal position and an audio path from the second sound transducer arrangement (107) to the nominal position.
    [0006]
    SOUND REPRODUCTION SYSTEM, according to claim 5, characterized in that it additionally comprises an adjuster arranged to receive an input signal from a microphone positioned in the nominal position (211) and to adjust at least one of the time difference and the difference of level in response to the microphone signal.
    [0007]
    SOUND REPRODUCTION SYSTEM, according to claim 1, characterized in that the audio signal is a spatial channel of a surround sound signal, and the drive circuit (103) is further arranged to generate the second drive signal in response to a second spatial channel of the surround sound signal.
    [0008]
    SOUND REPRODUCTION SYSTEM, according to claim 1, characterized in that the first arrangement of the sound transducer (105) is arranged to radiate a directional sound that reaches the nominal position from the first direction through at least one reflection.
    [0009]
    SOUND REPRODUCTION SYSTEM, according to claim 1, characterized in that the first arrangement of the sound transducer (105) is arranged to generate a virtual sound source in the first position; and the second arrangement of the sound transducer (107) comprises a loudspeaker positioned in the second position.
    [0010]
    SOUND REPRODUCTION SYSTEM, according to claim 1, characterized in that the second arrangement of the sound transducer (107) is arranged to generate a virtual sound source in the second position; and the first arrangement of the sound transducer (105) comprises a loudspeaker positioned in the first position.
    [0011]
    SOUND REPRODUCTION SYSTEM, according to claim 1, characterized in that the second position is such that an angle between a direction corresponding to the second position and the first direction is not less than 20 °.
    [0012]
    SOUND REPRODUCTION SYSTEM, according to claim 1, characterized by the sound confusion cone defining a set of positions for which an audio path delay varies by no more than 50 microseconds and a path loss varies by no more than 1 dB.
    [0013]
    METHOD FOR PRODUCING AN AUDIO SIGNAL AS PROCEDURES FROM A FIRST DIRECTION WITH RESPECT TO A NOMINAL POSITION (211) AND A NOMINAL ORIENTATION FROM A LISTENER, the method comprising: generating a first drive signal for a first sound transducer arrangement (105) and a second drive signal for a second sound transducer arrangement (107) of the audio signal; the first arrangement of the sound transducer (105) generating the sound that reaches the nominal position (211) from a first position corresponding to the first direction; the second arrangement of the sound transducer (107) generating the sound that reaches the nominal position (211) from a second position corresponding to a different direction than that of the first direction; and in what the first position and the second position are located in a sound confusion cone for the nominal position (211) and the nominal direction; characterized by the first trigger signal being generated to correspond to the higher frequency range of the audio signal than the second trigger signal; and at least one of the first sound transducer arrangement (105) and the second sound transducer arrangement (107) comprises a speaker positioned in the first position and the second position respectively.
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    同族专利:
    公开号 | 公开日
    EP2596649A1|2013-05-29|
    WO2012011015A9|2012-08-23|
    JP2013535894A|2013-09-12|
    RU2013107794A|2014-08-27|
    JP5992409B2|2016-09-14|
    EP2596649B1|2015-09-09|
    CN103053180A|2013-04-17|
    BR112013001414A2|2016-05-24|
    US20130121516A1|2013-05-16|
    WO2012011015A1|2012-01-26|
    US9107018B2|2015-08-11|
    RU2589377C2|2016-07-10|
    CN103053180B|2016-03-23|
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    法律状态:
    2016-09-06| B25D| Requested change of name of applicant approved|Owner name: KONINKLIJKE PHILIPS N. V. (NL) |
    2016-09-20| B25G| Requested change of headquarter approved|Owner name: KONINKLIJKE PHILIPS N. V. (NL) |
    2018-12-26| B06F| Objections, documents and/or translations needed after an examination request according [chapter 6.6 patent gazette]|
    2019-10-22| B06U| Preliminary requirement: requests with searches performed by other patent offices: procedure suspended [chapter 6.21 patent gazette]|
    2020-06-23| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application [chapter 6.1 patent gazette]|
    2020-10-06| B09A| Decision: intention to grant|
    2021-01-05| B09X| Decision of grant: republication|
    2021-04-06| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 11/07/2011, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    EP10170382.5|2010-07-22|
    EP10170382|2010-07-22|
    PCT/IB2011/053072|WO2012011015A1|2010-07-22|2011-07-11|System and method for sound reproduction|
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