Acoustic crosstalk cancellation and virtual loudspeaker technology

Abstract

The embodiments provide methods, apparatus, and systems for performing crosstalk cancellation and / or virtual speaker generation. An audio processor may include crosstalk cancellation circuitry and linearization circuitry. The linearization circuitry may compensate the frequency response of the crosstalk cancellation circuitry to provide a flat overall frequency response. The virtual speaker circuitry may receive an input signal associated with an output channel and pass the input signal to the output channel without modification. The virtual speaker circuitry generates a virtualized signal based on the input signal and passes the virtualized signal to another physical channel. The virtualized signal may be further generated based on the same-side head correlation transfer function (HRTF) and the opposite-side HRTF, corresponding to the virtual speaker position of the virtual speaker generated by the virtual speaker circuitry. Other embodiments may be described and / or claimed.

Description

[0001] Related applications

[0002] This application claims priority to U.S. Application 16 / 857,033, filed April 23, 2020, entitled “ACOUSTIC CROSSTALK CANCELLATION ANDVIRTUAL SPEAKERS TECHNIQUES”. Technical Field

[0003] The embodiments described herein relate to the field of audio reproduction, and more specifically, to acoustic crosstalk cancellation and virtual speaker technology. Background Technology

[0004] In audio reproduction systems, acoustic crosstalk occurs when the left speaker directs acoustic energy into the listener's right ear and / or the right speaker directs acoustic energy into the listener's left ear. Some systems implement crosstalk cancellation processes to remove this unwanted acoustic energy. However, these crosstalk cancellation processes introduce spectral artifacts (e.g., comb filtering in feedback operations).

[0005] Furthermore, some audio reproduction systems implement virtual speaker technology to make the listener perceive the sound as originating from a source other than the physical location of the speaker. This is typically achieved by manipulating the source audio to include psychoacoustic location cues. For example, existing methods perform head-related impulse response (HRIR) convolutions on each channel to add psychoacoustic location cues. However, these virtual speaker techniques also introduce spectral artifacts into the output signal. Attached Figure Description

[0006] The embodiments will be readily understood from the following detailed description taken in conjunction with the accompanying drawings and claims. In the drawings, the embodiments are illustrated by way of example rather than limitation.

[0007] Figure 1 An audio processor with crosstalk cancellation circuitry and linearization circuitry according to various embodiments is schematically illustrated.

[0008] Figure 2 Example implementations of crosstalk cancellation circuits and linearization circuits according to various embodiments are schematically illustrated.

[0009] Figure 3 An audio processor having a virtual speaker circuit, a crosstalk cancellation circuit, and a linearization circuit according to various embodiments is schematically illustrated.

[0010] Figure 4 An audio processor with virtual speaker circuitry according to various embodiments is schematically illustrated.

[0011] Figure 5 The illustrations schematically depict example implementations of virtual speaker circuits according to various embodiments.

[0012] Figure 6 The illustration schematically depicts a listening environment for demonstrating a virtual speaker method according to various embodiments.

[0013] Figure 7 An audio reproduction system according to various embodiments is schematically illustrated, which can implement the crosstalk cancellation methods and / or virtual speaker methods described herein. Detailed Implementation

[0014] The various embodiments described herein depict an audio processor that performs crosstalk cancellation and / or generates one or more virtual speakers. For example, the audio processor may include a crosstalk cancellation circuit and a linearization circuit coupled in series between an input and an output audio terminal. The crosstalk cancellation circuit may provide a crosstalk cancellation signal to the output terminal based on the input signal to eliminate crosstalk. The crosstalk cancellation circuit has a first frequency response. The linearization circuit has a second frequency response to provide a flat (i.e., equal to 1) overall frequency response over the operating range for the crosstalk cancellation method. For example, the second frequency response may be the inverse of the first frequency response. Therefore, the combination of the linearization circuit and the crosstalk cancellation circuit can provide crosstalk cancellation for the output signal while also providing a flat frequency response.

[0015] Additionally or alternatively, the audio processor may include virtual speaker circuitry. The virtual speaker circuitry may receive input signals from physical channels of a multi-channel listening environment. The virtual speaker circuitry may pass the unmodified input signals to a first output associated with a physical channel (e.g., a same-side output). The virtual speaker circuitry may generate a virtualized signal based on the input signals and provide the virtualized signal to a second output associated with a second physical channel (e.g., a opposite-side output). The virtualized signal may be further generated based on the same-side head correlation transfer function (HRTF) and the opposite-side HRTF corresponding to the virtual speaker's location, as described further below. Therefore, the virtual speaker method does not introduce spectral artifacts into the same-side output. Furthermore, the virtual speaker method can operate in real time and may require limited digital signal processing resources, thus allowing its use across a wide range of product price categories.

[0016] These and other embodiments will be described in further detail below.

[0017] In this detailed description, reference is made to the accompanying drawings, which form a part of this detailed description and are illustrated in the drawings by way of exemplary embodiments that can be implemented. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope. Therefore, the detailed description should not be construed as limiting.

[0018] Various operations can be described sequentially as a plurality of discrete operations in a manner that may aid in understanding the embodiments; however, the order of description should not be construed as implying that these operations are sequentially related.

[0019] This description may use perspective-based descriptions, such as top / bottom, back / front, and top / bottom. This description is used only to facilitate discussion and is not intended to limit the application of the disclosed embodiments.

[0020] The terms “coupling” and “connection”, as well as their derivatives, may be used. It should be understood that these terms are not intended to be synonyms. Rather, in certain embodiments, “connection” may be used to indicate that two or more elements are in direct physical or electrical contact with each other. “Coupling” can mean that two or more elements are in direct physical or electrical contact with each other. However, “coupling” can also mean that two or more elements are not in direct contact with each other, but still cooperate or interact with each other.

[0021] For descriptive purposes, phrases of the form "A / B" or "A and / or B" represent (A), (B), or (A and B). For descriptive purposes, phrases of the form "at least one of A, B, and C" represent (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C). For descriptive purposes, phrases of the form "(A)B" represent (B) or (AB), meaning that A is an optional element.

[0022] This description may use the term "embodiment" or "multiple embodiments," each of which may refer to one or more identical or different embodiments. Furthermore, the terms "comprising," "including," "having," etc., used with respect to embodiments are synonymous and are generally intended as "open" terms (e.g., the term "comprising" should be interpreted as "including but not limited to," the term "having" should be interpreted as "at least having," the term "including" should be interpreted as "including but not limited to," etc.).

[0023] As used herein, the terms “circuitry” or “circuit” may refer to or be part of or include the following components: application-specific integrated circuits (ASICs), electronic circuits, processors (shared, dedicated, or grouped) and / or memories (shared, dedicated, or grouped) that execute one or more software or firmware programs, combinational logic circuits, and / or other suitable components that provide the said functionality.

[0024] Regarding the use of any plural and / or singular terms in this document, those skilled in the art can translate them from plural to singular and / or from singular to plural as appropriate for the context and / or application. For clarity, various singular / plural permutations may be clearly illustrated herein.

[0025] Figure 1 An audio processor 100 according to various embodiments is illustrated. The audio processor 100 may receive an input audio signal x[n] at an input terminal 102 and generate an output audio signal y[n] at an output terminal 104. The audio processor 100 may include a crosstalk cancellation circuit 106 and a linearization circuit 108 coupled in series between the input terminal 102 and the output terminal 104. For example, in some embodiments, the crosstalk cancellation circuit 106 may be coupled along the signal path after the linearization circuit 108 (e.g., between the linearization circuit 108 and the output terminal 104).

[0026] In some embodiments, the input audio signal x[n] may correspond to one channel of an audio reproduction system with multiple channels. The audio reproduction system may include an audio processor 100 for each individual channel of the system. In some embodiments, the audio processor 100 may be implemented in a dual-channel audio system with a left speaker and a right speaker. Additionally or alternatively, the audio processor 100 may be implemented in a multi-channel audio system (e.g., a surround sound system) with more than two speakers. A multi-channel audio system may include additional speakers (e.g., listener-level speakers) in the same plane as the left and right speakers and / or additional speakers (e.g., height speakers) in one or more other planes.

[0027] In various embodiments, in some embodiments, the audio processors 100 for different channels may be implemented in the same processing circuitry (e.g., a digital signal processor) and may or may not include shared components. Alternatively or additionally, the audio reproduction system may include multiple integrated circuits having separate audio processors for one or more respective channels. In some embodiments, the audio processor 100 may receive input audio signals as digital signals (e.g., from a digital source and / or via an analog-to-digital converter (ADC)). The output audio signal may be converted into an analog audio signal by a digital-to-analog converter (DAC) before being passed to a speaker.

[0028] In various embodiments, the crosstalk cancellation circuit 106 can generate an output audio signal based on its input audio signal to eliminate crosstalk artifacts in the audio signal (e.g., preventing sound energy intended for one ear of a listener from reaching the other ear). The crosstalk cancellation circuit 106 can have a non-linear frequency response, as referenced below. Figure 2 Further discussion is needed. Therefore, the crosstalk cancellation circuit 106 may introduce spectral artifacts into the output signal.

[0029] In various embodiments, linearization circuitry 108 may be included to compensate for the frequency response of crosstalk cancellation circuitry 106, thereby providing a flat overall frequency response of the audio processor 100 (e.g., over the operating range of crosstalk cancellation circuitry 106 and / or linearization circuitry 108). For example, linearization circuitry 108 may pre-distort the input audio signal x[n] to generate an intermediate audio signal m[n] provided to crosstalk cancellation circuitry 106. Crosstalk cancellation circuitry 106 may process the intermediate audio signal m[n] to generate an output audio signal y[n]. The frequency response of linearization circuitry 108 may be the inverse of the frequency response of crosstalk cancellation circuitry 106. Therefore, with both linearization circuitry 108 and crosstalk cancellation circuitry 106 processing the audio signal, the overall frequency response may be flat while still providing the desired crosstalk cancellation. Reference is made below. Figure 2 These concepts will be described further.

[0030] Figure 2 An audio processor 200 according to various embodiments is illustrated, which may correspond to an audio processor 100. The audio processor 200 may receive an input audio signal x[n] at an input terminal 202 and provide an output audio signal y[n] at an output terminal 204. As discussed above, in some embodiments, the input audio signal x[n] may correspond to a channel of an audio reproduction system having multiple channels.

[0031] In various embodiments, the audio processor 200 may include a crosstalk cancellation circuit 206 and a linearization circuit 208 coupled in series (also referred to as cascaded) between an input terminal 202 and an output terminal 204. For example, as Figure 2 As shown, linearization circuit 208 can be coupled into the signal path earlier than crosstalk cancellation circuit 206. Linearization circuit 208 can receive input audio signal x[n] and generate intermediate audio signal m[n], which is provided to crosstalk cancellation circuit 206 (e.g., at intermediate node 216). Crosstalk cancellation circuit 206 can receive intermediate audio signal m[n] and generate output audio signal y[n]. Figure 2 The crosstalk cancellation circuit 206 shown can be illustrated as a signal path of a larger crosstalk cancellation circuit that includes multiple inputs and outputs (e.g., corresponding to different input channels and / or output channels).

[0032] In various embodiments, the crosstalk cancellation circuit 206 may modify its input audio signal (e.g., m[n]) to eliminate crosstalk artifacts. For example, the crosstalk cancellation circuit 206 may include a filter 210, a delay element 212, and / or an attenuation element 214, coupled in a feedback loop from the output 204 to an adder 218, which is coupled to the input of the crosstalk cancellation circuit 206 (e.g., intermediate node 216). The adder 218 subtracts the feedback from the feedback loop of the crosstalk cancellation circuit 206 from the input audio signal to produce an output audio signal y[n] at the output 204. Some embodiments may include additional feedback loops and / or additional or different processing elements on the feedback loop of the crosstalk cancellation circuit 206.

[0033] The values ​​and / or configurations of filter 210, delay element 212, and / or attenuation element 214 can be determined based on any suitable factors, such as system configuration (e.g., the number of speakers and / or speaker layout), expected, measured, or determined listener position, head-related transfer function, expected output function, etc.

[0034] Observing the crosstalk cancellation circuit 206 in isolation (e.g., without the linearization circuit 208), the output (y[n]) of the crosstalk cancellation circuit 206 in the discrete-time domain based on the input (m[n]) of the crosstalk cancellation circuit 206 can be given by equation (1):

[0035]

[0036] Where K1 is the delay value of delay element 212, a1 is the attenuation value of attenuation element 214, and h1[n] is the filtering function of filter 210.

[0037] Transforming equation (1) to the frequency domain and performing some algebraic operations results in the frequency response of the crosstalk cancellation circuit 206 according to equation (2):

[0038]

[0039] Therefore, as demonstrated by equation (2), the crosstalk cancellation provided by the feedback loop of the crosstalk cancellation circuit 206 has a non-uniform frequency response (e.g., introducing spectral artifacts).

[0040] In various embodiments, linearization circuit 208 generates an intermediate audio signal m[n], which is provided as input to crosstalk cancellation circuit 206 to balance the frequency effects of the feedback loop and provide a uniform total frequency response for audio processor 200. For example, linearization circuit 208 may include filter 220, delay element 222, and / or attenuation element 224, coupled in a feedforward loop from input 202 to adder 226, which is coupled to intermediate node 216. Adder 226 adds the feedforward signal from the feedforward loop to the output of linearization circuit 208 to produce the intermediate audio signal m[n].

[0041] Observing the linearization circuit 208 in isolation, the output of the linearization circuit 208 is given by equation (3):

[0042]

[0043] Where K2 is the delay value of delay element 222, a2 ​​is the attenuation value of attenuation element 224, and h2[n] is the filtering function of filter 220.

[0044] Transforming equation (3) to the frequency domain and performing some algebraic operations, we obtain a frequency response of 208 based on equation (4):

[0045]

[0046] Combining equations (2) and (4) provides the total frequency response of the audio processor 200 shown in Figure (5):

[0047]

[0048] Therefore, it can be seen that the total frequency response of the audio processor 200 will be 1 (i.e., flat on the frequency spectrum) if the following condition is met:

[0049]

[0050] Therefore, the elements of the feedback loop of the crosstalk cancellation circuit 206 and the feedforward loop of the linearization circuit 208 can be designed and / or controlled to satisfy the conditions described above in equation (6). For example, the control circuit (e.g., implemented in a digital signal processor) can control the values ​​of filters, delays, attenuations, and / or other values ​​to be the same on the feedback loop and the feedforward loop, and the same between (one or more) feedback loops and (one or more) corresponding feedforward loops.

[0051] Audio processor 200 may include multiple crosstalk cancellation circuits 206 and linearization circuits 208 and / or additional signal paths to generate an output audio signal from two or more input audio signals (e.g., corresponding to different channels). The resulting audio processor 200 will eliminate acoustic crosstalk in the audio signals while also providing a flat frequency response. The elements of audio processor 200 can be configured with any desired delay, operating band, and / or attenuation level (e.g., by adjusting the values ​​of filters 210 and 220, delay elements 212 and 222, and / or attenuation elements 214 and 224), as long as the conditions in equation (6) remain unchanged.

[0052] As discussed above, this document also describes an audio processing method for virtual speakers, as well as associated apparatus and systems. The virtual speaker method can create an immersive spatial audio listening environment reproduced from a speaker system containing two or more discrete drive units (e.g., speakers) of audio from stereo or multi-channel (e.g., more than two channels) source audio. The multi-channel listening environment may include two or more physical speakers corresponding to individual physical channels of the environment. The multi-channel listening environment may further include one or more virtual speakers associated with corresponding virtual speaker locations that are different from the physical speaker locations. Virtual speakers can be generated by the virtual speaker method by modifying the audio signals provided to one or more physical speakers so that the listener perceives virtual output channels originating from the corresponding virtual speaker locations. In various embodiments, the physical speakers may include headphone speakers and / or external speakers.

[0053] In various embodiments, in addition to the linear crosstalk cancellation process described herein, virtual speaker methods can also be implemented to generate an immersive listening environment free of spectral artifacts. For example, Figure 3An audio processor 300 according to some embodiments is illustrated. The audio processor 300 includes a linearization circuit 308 and a crosstalk cancellation circuit 306 coupled between an input 302 and an output 304. The linearization circuit 308 and / or the crosstalk cancellation circuit 306 may correspond to the respective linearization circuits 108 and / or 208 and / or crosstalk cancellation circuits 106 and / or 206 described herein. The audio processor 300 may also include a virtual speaker circuit 310 coupled between the input 302 of the audio processor 300 and the input of the linearization circuit 308. The virtual speaker circuit 310 can implement the virtual speaker method described herein.

[0054] Alternatively, the virtual speaker method can be implemented without crosstalk cancellation (e.g., when used with headphones), or by utilizing a different crosstalk cancellation method than that described herein. For example, Figure 4 An audio processor 400 is illustrated, which includes a virtual speaker circuit 410 coupled in series between an input 402 and an output 404. The virtual speaker circuit 410 can implement the virtual speaker method described herein.

[0055] In various embodiments of the virtual speaker method, for a given input channel associated with a physical output channel, the input audio signal can be delivered to the corresponding physical speaker without any modification to the virtual speaker processing method (although the input audio signal can be processed by other processing operations that can be used, such as crosstalk cancellation). A virtual speaker can be generated by providing additional virtualized audio signals to one or more other physical speakers.

[0056] The virtual speaker approach operates by creating a differential filter, which, along with additional signal processing, is applied to the input audio stream to provide psychoacoustic cues to the listener, thereby creating the impression of a surround sound environment. This method can be implemented on any playback device containing two separate, addressable acoustic playback channels with physically isolated transducers.

[0057] For example, Figure 5 A virtual speaker circuit 500 is illustrated, which can implement a virtual speaker method according to various embodiments. In some embodiments, the virtual speaker circuit 500 may correspond to virtual speaker circuits 310 and / or 410. The virtual speaker circuit 500 can receive an input signal x at input terminal 502. L [n]. Input signal x L [n] can correspond to the physical channel in a multi-channel listening environment (e.g., the left speaker channel). The virtual speaker circuit 500 can transmit the unmodified input signal x L[n] is passed to the first output terminal 504 corresponding to the physical channel (e.g., to the physical speaker and / or subsequent processing circuitry of the physical channel (e.g., linearization circuitry and / or crosstalk cancellation circuitry)). Therefore, the output signal y of the physical channel... L [n] and the input signal x of the physical channel L [n] are the same.

[0058] Furthermore, the virtual speaker circuit 500 can be based on the input signal x L [n] Generates virtualized signal y R [n], and the virtualized signal can be transmitted to a second output 506 corresponding to a different physical channel (e.g., the right speaker channel in this example). The virtualized signal can also be generated based on the same-side HRTF and opposite-side HRTF corresponding to the virtual speaker position, as further described below. For example, in some embodiments, the virtual speaker circuit 500 may include a filter 520, an attenuation element 524, and / or a delay element 522 to direct the input signal x L [n] provides the corresponding filtering, attenuation, and delay to generate the virtualized signal y. R [n]. Other embodiments may include fewer components, additional components, and / or different component arrangements to generate virtualized signals.

[0059] Figure 6 The illustration shows a listening environment 600 in which a virtual speaker method can be implemented. Listening environment 600 may include a left speaker 602 and a right speaker 604. The virtual speaker method can be implemented by considering a listening position 606 relative to the positioning of speakers 602 and 604. For example, speakers 602 and 604 may be positioned such that the reference axes of the two speakers 602 and 604 are parallel to each other and parallel to an imaginary line drawn parallel to the ground from the tip of the listener's nose to the back of the listener's head at listening position 606, equidistant from the two sources. One implementation of this technique processes the incoming stereo audio into an azimuth-only spatial environment (e.g., without generating an elevation cue). In some embodiments, the method can be modified to achieve other speaker arrangements and / or listener positions. For example, some embodiments may include a virtual height channel with an elevation cue.

[0060] In listening environment 600, listening position 606 can be located at the center of a box defined by points A, B, C, and D at a corner. In existing audio spatialization methods, input audio is convolved with head-related impulse response (HRIR) data to generate appropriate delays and spectral shifts, thereby encoding the audio with positional or locational information. One drawback of this approach is that it introduces spectral variations into all processed audio. In contrast, the virtual loudspeaker method described herein can create a spatialized sound field at the listening position without introducing any spectral variations.

[0061] The virtual speaker method is described with respect to a listening environment 600 to spatialize a stereo audio signal for playback through stereo physical speakers. For ease of understanding, the process is described for one channel of input stereo audio. The process is the same for another channel of input audio, except that the channel is specified. The process can also be used with two or more physical speakers (e.g., by including additional process paths and / or modifying how the spatialized signal is distributed across multiple physical speakers).

[0062] In one virtualization method, the left input time-domain audio channel x L Convolution with two channels of HRIR corresponding to the desired left-side positioning: i-side (h LL ) and the opposite side (h LR The result is two output signals, one sent to the left channel of the reproduction system (y). L ), and a right channel (y) sent to the reproduction system. R ):

[0063]

[0064] Transforming equation (7) to the frequency domain produces equation (8):

[0065]

[0066] Equation (8) can be rearranged to obtain an expression for the output on the opposite side based on the output on the same side:

[0067]

[0068] The final form of Equation (9) shows that the psychoacoustic localization effect given by the contralateral output signal is a linear function of the ipsilateral output signal, modified by the difference between the ipsilateral and contralateral head correlation transfer functions (HRTF) in the frequency domain. According to the various embodiments described here, the ipsilateral output of the virtual loudspeaker process is the unmodified input channel. Therefore, the contralateral output can be generated based on Equation (9). For example, the ipsilateral and contralateral outputs of the virtual loudspeaker method can be as follows:

[0069]

[0070] Therefore, in various embodiments, by applying a filter equivalent to the ratio of the two HRTFs corresponding to the desired localization origin (e.g., by...) Figure 5 The 520 filter (applied to this application) can arbitrarily generate spatialized signals from source audio across any listening dimension. See again... Figure 6 Left-to-Right (STS) processing 608 can be applied to spatialize the input audio in the AB dimension. Additionally or alternatively, a Front-to-Back (FTB) process 610 can be applied to spatialize the input audio in the AC dimension. Processes 608 and / or 610 may include additional signal processing elements such as delay, attenuation, and phase adjustment (e.g., as...). Figure 5 (As shown), to create appropriate positioning cues. Phase adjustment can be provided by filter 520, for example, using one or more full-pass filters.

[0071] In addition to or in place of STS process 608 and / or FTB process 610, some embodiments may include spatialization processes in one or more other dimensions. For example, some embodiments may additionally or alternatively include a boosting process for spatializing the input audio in the vertical dimension, and / or a diagonal spatialization process for spatializing the input audio in the diagonal dimension.

[0072] In various embodiments, the crosstalk cancellation methods and / or virtual speaker methods described herein can be implemented in any suitable audio reproduction system. Figure 7 An example of system 700 is schematically illustrated, which includes audio processor circuitry 702 capable of implementing crosstalk cancellation methods and / or virtual speaker methods. For example, audio processor circuitry 702 may include audio processors 100, 200, 300 and / or 400 described herein, and / or virtual speaker circuitry 500.

[0073] In various embodiments, system 700 can receive input audio signals, which may be multi-channel input audio signals. The input audio signals may be received in digital and / or analog form. The input audio signals may be received from another component of system 700 (e.g., a media player and / or storage device) and / or from another device communicatively coupled to system 700 (e.g., via a wired connection (e.g., Universal Serial Bus (USB), Optical Digital, Coaxial Digital, High Definition Media Interconnect (HDMI), Wired Local Area Network (LAN) etc.) and / or a wireless connection (e.g., Bluetooth, Wireless Local Area Network (WLAN, such as WiFi), Cellular, etc.)).

[0074] In various embodiments, the audio processor circuit 702 can generate an output audio signal and pass it to the amplifier circuit 704. The audio processor circuit 702 can implement one or more crosstalk cancellation circuits and / or one or more virtual speaker circuits described herein to provide crosstalk cancellation and / or generate one or more virtual speakers, respectively. The output audio signal can be a multi-channel audio signal with two or more output channels.

[0075] Amplifier circuit 704 can receive output audio signals from audio processor circuit 702 via a wired and / or wireless connection. Amplifier circuit 704 can amplify the output audio signals received from audio processor circuit 702 to generate amplified audio signals. Amplifier circuit 704 can transmit the amplified audio signals to two or more physical speakers 706. Speakers 706 can include any suitable audio output device to produce audible sound based on the amplified audio signals, such as external speakers and / or headphone speakers. Speakers 706 can be standalone speakers to receive amplified audio signals from amplifier circuits, and / or can be integrated into devices that also include amplifier circuit 704 and / or audio processor circuit 702. For example, speaker 706 can be a passive speaker that does not include amplifier circuit 704 and / or an active speaker that includes amplifier circuit 704 integrated into the same device.

[0076] In one example, speaker 706 may be an earphone speaker, for example, having a left speaker providing audio to the listener's left ear and a right speaker providing audio to the listener's right ear. The earphone may receive input audio via a wired and / or wireless interface. The earphone may or may not include an audio amplifier 704 (e.g., for reproducing audio from a wireless interface). In some embodiments, the earphone may include audio processor circuitry 702 to apply the virtual speaker method described herein. Alternatively, after applying the virtual speaker method, the earphone may receive processed audio from another device.

[0077] In various embodiments, some or all of the components of system 700 may be included in any suitable device, such as a mobile phone, computer, audio / video receiver, integrated amplifier, stand-alone audio processor (including audio / video processor), active speaker (e.g., smart speaker or non-smart active speaker), headphones, external USB DAC device, etc.

[0078] In various embodiments, the audio processor circuit 702 may include one or more integrated circuits, such as one or more digital signal processor circuits. Additionally or alternatively, the system 700 may include one or more additional components, such as one or more processors, memory (e.g., random access memory (RAM), mass storage (e.g., flash memory, hard disk drive (HDD) etc.), antenna, display, etc.).

[0079] Although certain embodiments have been illustrated and described herein, those skilled in the art will understand that the illustrated and described embodiments can be replaced with various alternatives and / or equivalent embodiments or implementations intended to achieve the same purpose without departing from the scope of the invention. It will be readily understood by those skilled in the art that embodiments can be implemented in a great many ways. This application is intended to cover any modifications or variations of the embodiments discussed herein. Therefore, it is clearly intended that the embodiments be limited only by the claims and their equivalents.

Claims

1. An audio processor circuit, comprising: The input terminal is used to receive input audio signals; The output terminal is used to provide the output audio signal; A crosstalk cancellation circuit is coupled between the input and output terminals to provide an output audio signal with a crosstalk cancellation signal, wherein the crosstalk cancellation circuit has a first frequency response; A linearization circuit, coupled in series with a crosstalk cancellation circuit between the input and output, wherein the linearization circuit has a second frequency response to provide a flat total frequency response for the audio processor circuit over its operating range; The crosstalk cancellation circuit includes a feedback loop, wherein a filter, an attenuation element, and a delay element are coupled in the feedback loop between the output and the input of the crosstalk cancellation circuit. in, The filter is a first filter, the attenuation element is a first attenuation element, and the delay element is a first delay element, wherein the linearization circuit includes a feedforward loop, wherein the second filter, the second attenuation element, and the second delay element are coupled in the feedforward loop between the input and the output of the linearization circuit.

2. The audio processor circuit according to claim 1 further includes a control circuit for controlling one or more values ​​of the linearization circuit to be the same as one or more corresponding values ​​of the crosstalk cancellation circuit.

3. The audio processor circuit according to claim 1, wherein the linearization circuit is used to receive the input audio signal and generate an intermediate audio signal based on the input audio signal, and wherein the crosstalk cancellation circuit is used to receive the intermediate audio signal and generate the output audio signal based on the intermediate audio signal.

4. The audio processor circuit according to claim 3, wherein the first frequency response of the crosstalk cancellation circuit on the signal path between the input terminal and the output terminal is: Where Y(z) is the output audio signal, K1 is the first delay value, a1 is the first attenuation value, and H1(z) is the first filtering function; The second frequency response of the linearization circuit is: Where M(z) is the intermediate audio signal, X(z) is the input audio signal, K2 is the second delay value, a2 is the second attenuation value, and H2(z) is the second filter function; and in: and .

5. The audio processor circuit according to any one of claims 1 to 4, wherein, The input audio signal is a first input audio signal, and the audio processor circuit further includes a virtual speaker circuit for: Receive a second input audio signal, wherein the second input audio signal corresponds to a first physical channel of a multi-channel listening environment; The second input audio signal is transmitted to the crosstalk cancellation circuit as the first input audio signal of the first physical channel. A virtual channel for a multi-channel listening environment is generated based on the second input audio signal, wherein the virtual channel is associated with a virtual channel position, and wherein, in order to generate the virtual channel, the virtual speaker circuitry must: A virtualized audio signal is generated based on the second input audio signal, the ipsilateral head correlation transfer function (HRTF) corresponding to the virtual channel position, and the contralateral HRTF corresponding to the virtual channel position; and A second physical channel that provides virtualized audio signals to a multi-channel listening environment.

6. The audio processor circuit of claim 5, wherein the virtual speaker circuit transmits the second input audio signal to the crosstalk cancellation circuit without modification.

7. The audio processor circuit according to claim 5, wherein, The virtualized audio signal is generated according to the following formula: Where Y2 is the virtualized audio signal in the frequency domain, H 12 The opposite HRTF, H 11 X1 is the same-side HRTF, and X2 is the second input audio signal of the physical channel.

8. The audio processor circuit according to claim 1, wherein, The audio processor circuit is implemented in a multi-channel audio system with two or more speakers.

9. The audio processor circuit according to claim 8, wherein the multi-channel audio system is a surround sound system.

10. The audio processor circuit according to claim 8, wherein, The multi-channel audio system includes additional speakers in one or more other planes, including height speakers.

11. The audio processor circuit according to claim 1, wherein, The crosstalk cancellation circuit and the linearization circuit are implemented in the same processing circuit.

12. The audio processor circuit according to claim 1, wherein, The input audio signal is received as a digital signal from a digital source via an analog-to-digital converter.

13. An audio output system, comprising: Audio processor, including: A linearization circuit is used to receive an input audio signal and generate an intermediate audio signal based on the input audio signal, wherein the linearization circuit has a first frequency response; and A crosstalk cancellation circuit is used to receive the intermediate audio signal and generate an output audio signal to eliminate crosstalk in the intermediate audio signal, wherein the crosstalk cancellation circuit has a second frequency response to provide the audio processor with a flat total frequency response within its operating range; and An audio amplifier coupled to an audio processor amplifies the output audio signal and provides the output audio signal to one or more speakers; in, The crosstalk cancellation circuit includes a feedback loop, wherein a filter, an attenuation element, and a delay element are coupled in the feedback loop between the output and the input of the crosstalk cancellation circuit; Wherein, the filter is a first filter, the attenuation element is a first attenuation element, and the delay element is a first delay element, wherein the linearization circuit includes a feedforward loop having a second filter having the same filtering function as the first filter, a second attenuation element having the same attenuation value as the first attenuation element, and a second delay element having the same delay value as the first delay element, wherein the second filter, the second attenuation element, and the second delay element are coupled in the feedforward loop between the input and the output of the linearization circuit.

14. The audio output system according to claim 13, wherein, The first frequency response of the linearized circuit is: Where M(z) is the intermediate audio signal, X(z) is the input audio signal, K2 is the linearized delay value, a2 is the linearized attenuation value, and H2(z) is the linearized filter function; The second frequency response of the crosstalk cancellation circuit is: Where Y(z) is the output audio signal, K1 is the crosstalk delay value, a1 is the crosstalk attenuation value, and H1(z) is the crosstalk filtering function; and in: and .

15. The audio output system according to claim 14, wherein, The input audio signal is a first input signal, and the audio processor circuit further includes a virtual speaker circuit for: Receive a second input audio signal, wherein the second input audio signal corresponds to a first physical channel of a multi-channel listening environment; The unmodified second input audio signal is passed to the first input of the linearization circuit, where the first input is used for the first physical channel; A virtualized audio signal is generated based on the output audio signal, the ipsilateral head correlation transfer function (HRTF) corresponding to the virtual channel position, and the contralateral HRTF corresponding to the virtual channel position; and The virtualized audio signal is provided to a second input of the linearization circuit to generate a virtual channel associated with the location of the virtual channel, wherein the second input corresponds to a second physical channel of the multi-channel listening environment.

16. The audio output system according to claim 15, wherein, The virtualized audio signal is generated according to the following formula: Where Y2 is the virtualized audio signal in the frequency domain, H 12 The opposite HRTF, H 11 X1 is the same-side HRTF, and X2 is the second input audio signal of the first physical channel.

17. The audio output system according to any one of claims 13 to 16, further comprising one or more speakers coupled to the audio amplifier to receive the amplified output audio signal.

18. The audio output system according to claim 13, wherein, The linearization circuit and the crosstalk cancellation circuit are implemented in the same digital signal processor.

19. The audio output system of claim 13, wherein the one or more speakers include an earphone speaker, the earphone speaker including a left speaker for providing audio to the left ear of a listener and a right speaker for providing audio to the right ear of a listener.

20. The audio output system according to claim 13, wherein, The system is implemented in a device selected from the group consisting of a mobile phone, a computer, an audio / video receiver, an integrated amplifier, a standalone audio processor, an active speaker, headphones, and an external USB DAC device.

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