TELECOMMUNICATIONS

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62/612,252 filed December 29, 2017, the disclosure of which is hereby incorporated in its entirety by reference herein.

TECHNICAL FIELD

[0002] The present disclosure relates to a system and method for cancelling in-cabin noise from a vehicle at a far-end user of a telecommunications system.

BACKGROUND

[0003] Current vehicle cabin acoustics predicate that any sound that occurs in the cabin will generally be perceived as one noisy stimulus. Common examples of interference sources include road noise, wind noise, passenger speech, and multimedia content. The presence of these noise sources complicates speech perception by reducing speech intelligibility, signal-to noise ratio, and subjective call quality. Many modern techniques exist to improve the telecommunications experience for the near-end participants (i.e., driver or other occupants of the source vehicle), but thus far nothing has attempted to improve call quality for the far-end participants of telecommunication.

SUMMARY

[0004] A system of one or more computers can be configured to perform particular operations or actions by virtue of having software, firmware, hardware, or a combination of them installed on the system that in operation causes or cause the system to perform the actions. One or more computer programs can be configured to perform particular operations or actions by virtue of including instructions that, when executed by data processing apparatus, cause the apparatus to perform the actions. One general aspect includes a noise cancellation system for a vehicle including: a first microphone array, located in a cabin of the vehicle, configured to detect near-end speech from a near-end participant of a communications exchange and to generate a near-end speech signal indicative of the near-end speech. The noise cancellation system may also include a second microphone array, located in the cabin, configured to detect noise present in the cabin of the vehicle and generate a noise signal indicative of the noise. A digital signal processor may be configured to: receive the near-end speech signal and the noise signal; suppress noise in the near-end speech signal based on the noise signal; and generate a noise-suppressed, near-end speech signal. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0005] Implementations may include one or more of the following features. The digital signal processor may be further configured to receive an infotainment audio signal indicative of audio to be reproduced by a speaker in the cabin of the vehicle and to suppress noise in the near-end speech signal based on the noise signal and the infotainment audio signal. The noise cancellation system may further include: a telecommunications system, in communication with the digital signal processor, configured to receive the noise-suppressed, near-end speech signal and to transmit an outgoing telecommunications signal to a far-end participant of the communications exchange. The digital signal processor may be integrated into the telecommunications system. The digital signal processor may be a separate component from the telecommunications system.

[0006] The telecommunications system may be configured to generate an incoming telecommunications signal indicative of far-end speech received from the far-end participant of the communications exchange, the digital signal processor being further configured to process the near end speech signal based in part on the incoming telecommunications signal. The near-end speech signal may undergo echo cancellation based in part on the incoming telecommunications signal. The noise-suppressed, near-end speech signal may undergo echo suppression based in part on the incoming telecommunications signal. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium. [0007] Another general aspect includes a method for cancelling in-cabin noise from a vehicle at a far-end of a telecommunications system. The method may include receiving a near-end speech signal from a first microphone, the near-end speech signal indicative of near-end speech from a near end participant of a telecommunications exchange. The method may also include receiving a noise signal from a second microphone, the noise signal indicative of noise present in a cabin of the vehicle. The method may also include suppressing noise in the near-end speech signal based on the noise signal to obtain a noise-suppressed, near-end speech signal. The method may further include transmitting the noise-suppressed, near-end speech signal to the telecommunications system for communicating the near-end speech to a far-end participant of the telecommunications exchange as an outgoing telecommunications signal. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0008] Implementations may include one or more of the following features. The method may further include: receiving an infotainment audio signal indicative of audio to be reproduced by a speaker in the cabin of the vehicle, where suppressing the noise in the near-end speech signal is based on the noise signal and the infotainment audio signal. The method may further include: receiving an incoming telecommunications signal indicative of far-end speech received from the far- end participant of the telecommunications exchange. The method may also include processing the near-end speech signal based in part on the incoming telecommunications signal. Processing the near-end speech signal based in part on the incoming telecommunications signal may include cancelling an echo in the near-end speech signal based in part on the incoming telecommunications signal. Processing the near-end speech signal based in part on the incoming telecommunications signal may include suppressing an echo in the noise-suppressed, near-end speech signal based in part on the incoming telecommunications signal. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer-accessible medium.

[0009] Another general aspect includes a digital signal processor for cancelling in-cabin noise from a vehicle. The digital signal processor may include a first beamformer configured to receive first audio signals from a first microphone array and to generate a near-end speech signal, the first audio signals being indicative of near-end speech from a near-end participant of a communications exchange. The digital signal processor may also include a second beamformer configured to receive second audio signals from a second microphone array and to generate a noise signal, the second audio signals being indicative of noise present in a cabin of the vehicle. The digital signal processor may further include a noise suppressor configured to receive both the near end speech signal and the noise signal and to generate a noise-suppressed, near-end speech signal by suppressing noise in the near-end speech signal based on the noise signal. Other embodiments of this aspect include corresponding computer systems, apparatus, and computer programs recorded on one or more computer storage devices, each configured to perform the actions of the methods.

[0010] Implementations may include one or more of the following features. The noise suppressor may be further configured to receive an infotainment audio signal indicative of audio to be reproduced by a speaker in the cabin of the vehicle and to generate the noise-suppressed, near-end speech signal by suppressing noise in the near-end speech signal based on the noise signal and the infotainment audio signal. The noise-suppressed, near-end speech signal may be converted to an outgoing telecommunications signal for communicating to a far-end participant of the communications exchange by a telecommunications system.

[0011] The digital signal processor may further include an echo canceller configured to receive the near-end speech signal and an incoming telecommunications signal indicative of far-end speech received from a far-end participant of the communications exchange and remove line or acoustic echo from the near-end speech signal based in part on the incoming telecommunications signal. The incoming telecommunications signal may be digitally processed prior to being received by the echo canceller.

[0012] The digital signal processor may further include an echo suppressor configured to receive the noise-suppressed, near-end speech signal and an incoming telecommunications signal indicative of far-end speech received from a far-end participant of the communications exchange and to remove line and/or acoustic echo from the noise-suppressed, near-end speech signal based in part on the incoming telecommunications signal. The incoming telecommunications signal may be digitally processed prior to being received by the echo suppressor. Implementations of the described techniques may include hardware, a method or process, or computer software on a computer- accessible medium. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 illustrates a telecommunications network for facilitating telecommunication between a near-end participant in a vehicle and a remote, far-end participant located outside the vehicle, according to one or more embodiments of the present disclosure;

[0014] FIG. 2 is a block diagram of an in-cabin noise cancellation system for far-end telecommunications, according to one or more embodiments of the present disclosure;

[0015] FIG. 3 is a simplified, exemplary flow diagram depicting a noise cancellation method

300 for far-end telecommunications, according to one or more embodiments of the present disclosure;

[0016] FIG. 4 illustrates an exemplary microphone placement, according to one or more embodiments of the present disclosure;

[0017] FIG. 5 illustrates an exemplary set-up for a headrest-based telecommunications system for a vehicle, according to one or more embodiments of the present disclosure; and

[0018] FIG. 6 illustrates another exemplary set-up for a headrest-based telecommunications system for a vehicle, according to one or more embodiments of the present disclosure.

DETAIFED DESCRIPTION

[0019] As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0020] Any one or more of the controllers or devices described herein include computer executable instructions that may be compiled or interpreted from computer programs created using a variety of programming languages and/or technologies. In general, a processor (such as a microprocessor) receives instructions, for example from a memory, a computer-readable medium, or the like, and executes the instructions. A processing unit includes a non-transitory computer- readable storage medium capable of executing instructions of a software program. The computer readable storage medium may be, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semi-conductor storage device, or any suitable combination thereof.

[0021] The present disclosure describes an in-vehicle noise-cancellation system for optimizing far-end user experience. The noise-cancellation system may improve the intelligibility of near-end speech at the far-end of a communications exchange, including a telecommunications exchange or dialogue with a virtual personal assistant, or the like. The noise-cancellation system may incorporate real-time acoustic input from the vehicle, as well microphones from a telecommunications device. Moreover, audio signals from small, embedded microphones mounted in the car can be processed and mixed into an outgoing telecommunications signal to effectively cancel acoustic energy from one or more unwanted sources in the vehicle. Audio playing from a known audio stream (e.g., music, sound effects, and dialog from a film audio) in the vehicle’s infotainment system, in addition to unwanted noise (e.g., children yelling and background conversations) captured by the embedded microphones, may be used as direct inputs to the noise- cancellation system. As direct inputs, these streams can, therefore, be cancelled from the outgoing telecommunications signal, thus providing the user’s far-end correspondent with much higher signal - to-noise ratio, call quality, and speech intelligibility.

[0022] FIG. 1 illustrates a telecommunications network 100 for facilitating a telecommunications exchange between a near-end participant 102 in a vehicle 104 and a remote, far- end participant 106 located outside the vehicle via a cellular base station 108. The vehicle 104 may include a telecommunications system 110 for processing incoming and outgoing telecommunications signals, collectively shown as telecommunications signals 112 in FIG. 1. The telecommunications system 110 may include a digital signal processor (DSP) 114 for processing audio telecommunications signals, as will be described in greater detail below. According to another embodiment, the DSP 114 may be a separate module from the telecommunications system 110. A vehicle infotainment system 116 may be connected to the telecommunications system 110. A first transducer 118 or speaker may transmit the incoming telecommunications signal to the near-end participant of a telecommunications exchange inside a vehicle cabin 120. Accordingly, the first transducer 118 may be located adjacent to a near-end participant or may generate a sound field localized at a particular seat location occupied by the near-end participant. A second transducer 122 may transmit audio from the vehicle’s infotainment system 116 (e.g., music, sound effects, and dialog from a film audio).

[0023] A first microphone array 124 may be located in the vehicle cabin 120 to receive speech of the near-end participant (i.e., driver or another occupant of the source vehicle) in a telecommunication. A second microphone array 126 may be located in the vehicle cabin 120 to detect unwanted audio sources (e.g., road noise, wind noise, background speech, and multimedia content), collectively referred to as noise. Collectively, the telecommunications system 110, the DSP 114, the infotainment system 116, the transducers 118, 122, and the microphone arrays 124, 126 may form an in-cabin noise cancellation system 128 for far-end telecommunications.

[0024] FIG. 2 is a block diagram of the noise cancellation system 128 depicted in FIG. 1. As show in FIG. 2, an incoming telecommunications signal 112a from a far-end participant (not shown) may be received by the DSP 114. The DSP 114 may be a hardware-based device, such as a specialized microprocessor and/or combination of integrated circuits optimized for the operational needs of digital signal processing, which may be specific to the audio application disclosed herein. The incoming telecommunications signal 112a may undergo automatic gain control at an automatic gain controller (AGC) 202. The AGC 202 may provide a controlled signal amplitude at its output, despite variation of the amplitude in the input signal. The average or peak output signal level is used to dynamically adjust the input-to-output gain to a suitable value, enabling the circuit to work satisfactorily with a greater range of input signal levels. The output from the AGC 202 may then be received by a loss controller 204 to undergo loss control, which is then passed to an equalizer 206 to equalize the incoming telecommunications signal 1 l2a. Equalization is the process of adjusting the balance between frequency components within an electronic signal. Equalizers strengthen (boost) or weaken (cut) the energy of specific frequency bands or“frequency ranges.”

[0025] The output of the equalizer 206 may be received by a limiter 208. A limiter is a circuit that allows signals below a specified input power or level to pass unaffected while attenuating the peaks of stronger signals that exceed this threshold. Limiting is a type of dynamic range compression; it is any process by which a specified characteristic (usually amplitude) of the output of a device is prevented from exceeding a predetermined value. Limiters are common as a safety device in live sound and broadcast applications to prevent sudden volume peaks from occurring. A digitally processed incoming telecommunications signal 112a' may then be received by the first transducer 118 for audible transmission to the near-end participant of the telecommunications exchange.

[0026] As also shown in FIG. 2, noise cancellation system 128 may include the first microphone array 124 and the second microphone array 126. The first microphone array 124 may include a plurality of small, embedded microphones strategically located in the vehicle cabin to receive speech from a near-end participant (i.e., driver or another occupant of the source vehicle) of the telecommunications exchange. The first microphone array 124 may be positioned as close to the near-end participant as possible, while being as far from reflective surfaces as possible. For instance, the first microphone array 124 may be embedded in a headrest or headliner or the like, as shown in FIG. 4. The second microphone array 126 may include a plurality of small, embedded microphones strategically located in the vehicle cabin to detect unwanted audio sources (e.g., road noise, wind noise, background speech, and multimedia content), collectively referred to as noise.

[0027] Both inputs to the first and second microphone arrays, near-end speech and noise, respectively, may be processed using the DSP 114. A set of first audio signals 209 (i.e., indicative of the near-end speech) from the first microphone array 124 may be fed into a first beamformer 210 for beamforming, while a set of second audio signals 211 (i.e., indicative of noise) may be fed into a second beamformer 212. Beamforming or spatial filtering is a signal processing technique used in sensor arrays for directional signal transmission or reception. This is achieved by combining elements in an array in such a way that signals at particular angles experience constructive interference while others experience destructive interference. Beamforming can be used at both the transmitting and receiving ends to achieve spatial selectivity. The improvement compared with omnidirectional reception/transmission is known as the directivity of the array. To change the directionality of the array when transmitting, a beamformer controls the phase and relative amplitude of the signal at each transmitter, to create a pattern of constructive and destructive interference in the wavefront. When receiving, information from different sensors is combined in a way where the expected pattern of radiation is preferentially observed.

[0028] The first beamformer 210 may output a near-end speech signal 213 indicative of the near-end speech detected by the first microphone array 124. Alternatively, the near-end speech signal 213 may be received by the DSP 114 directly from the first microphone array 124 or an individual microphone in the first microphone array. The second beamformer 212 may output a noise signal 218 indicative of the unpredictable, background noise detected by the second microphone array 126. Alternatively, the noise signal 218 may be received by the DSP 114 directly from the second microphone array 126 or an individual microphone in the second microphone array.

[0029] The near-end speech signal 213 may be received by an echo canceller 214 along with the digitally processed incoming telecommunications signal H2a' from the far-end participant 106. Echo cancellation is a method in telephony to improve voice quality by removing echo after it is already present. In addition to improving subjective quality, this process increases the capacity achieved through silence suppression by preventing echo from traveling across a network. There are various types and causes of echo with unique characteristics, including acoustic echo (sounds from a loudspeaker being reflected and recorded by a microphone, which can vary substantially over time) and line echo (electrical impulses caused by, e.g., coupling between the sending and receiving wires, impedance mismatches, electrical reflections, etc., which varies much less than acoustic echo). In practice, however, the same techniques are used to treat all types of echo, so an acoustic echo canceller can cancel line echo as well as acoustic echo. Echo cancellation involves first recognizing the originally transmitted signal that re-appears, with some delay, in the transmitted or received signal. Once the echo is recognized, it can be removed by subtracting it from the transmitted or received signal. Though this technique is generally implemented digitally using a digital signal processor or software, although it can be implemented in analog circuits as well.

[0030] The output of the echo canceller 214 may be mixed with the noise signal 218 (i.e., unpredictable noise) from the second beamformer 212 and an infotainment audio signal 220 (i.e., predictable noise) from the infotainment system 116 at a noise suppressor 216. Mixing the near-end speech signal 213 with the noise signal 218 and/or the infotainment audio signal 220 at the noise suppressor 216 can effectively cancel acoustic energy from one or more unwanted sources in the vehicle 104. The audio playing from a known audio stream (e.g., music, sound effects, and dialog from a film audio) in the vehicle’s infotainment system 116 may be considered predictable noise and may be used as a direct input to the noise-cancellation system 128 and cancelled or suppressed from the near-end speech signal 213. Moreover, additional unwanted and unpredictable noise (e.g., children yelling and background conversations) captured by the embedded microphones may also be used as direct inputs to the noise-cancellation system 128. The unwanted noise may be cancelled or suppressed from the near-end speech signal 213 by the noise suppressor 216 based on the noise signal 218 and the infotainment audio signal 220 before being communicated to the far-end participant as an outgoing telecommunications signal 112b. Noise suppression is an audio pre processor that removes background noise from the captured signal.

[0031] A noise-suppressed, near-end speech signal 213' may be output from the noise suppressor 216 and may be mixed with the processed incoming telecommunications signal 112a' from the far-end participant at an echo suppressor 222. Echo suppression, like echo cancellation, is a method in telephony to improve voice quality by preventing echo from being created or removing it after it is already present. Echo suppressors work by detecting a voice signal going in one direction on a circuit, and then inserting a great deal of loss in the other direction. Usually the echo suppressor at the far-end of the circuit adds this loss when it detects voice coming from the near-end of the circuit. This added loss prevents the speaker from hearing their own voice.

[0032] The output from the echo suppressor 222 may then undergo automatic gain control at an automatic gain controller (AGC) 224. The AGC 224 may provide a controlled signal amplitude at its output, despite variation of the amplitude in the input signal. The average or peak output signal level is used to dynamically adjust the input-to-output gain to a suitable value, enabling the circuit to work satisfactorily with a greater range of input signal levels. The output from the AGC 224 may then be received by an equalizer 226 to equalize the near-end speech signal. Equalization is the process of adjusting the balance between frequency components within an electronic signal. Equalizers strengthen (boost) or weaken (cut) the energy of specific frequency bands or“frequency ranges.”

[0033] The output from the equalizer 226 may be sent to a loss controller 228 to undergo loss control. The output may then be passed through a comfort noise generator (CNG) 230. CNG 230 is a module that inserts comfort noise during periods that there is no signal received. CNG may be used in association with discontinuous transmission (DTX). DTX means that a transmitter is switched off during silent periods. Therefore, the background acoustic noise abruptly disappears at the receiving end (e.g. far-end). This can be very annoying for the receiving party (e.g., the far-end participant). The receiving party might even think that the line is dead if the silent period is rather long. To overcome these problems,“comfort noise” may be generated at the receiving end (i.e., far- end) whenever the transmission is switched off. The comfort noise is generated by a CNG. If the comfort noise is well matched to that of the transmitted background acoustic noise during speech periods, the gaps between speech periods can be filled in such a way that the receiving party does not notice the switching during the conversation. Since the noise constantly changes, the comfort noise generator 230 may be updated regularly.

[0034] The output from the CNG 230 may then be transmitted by the telecommunications system to the far-end participant of the telecommunications exchange as the outgoing telecommunications signal 112b. By cancelling noise inputs directly from the outgoing telecommunications signal, a user’s far-end correspondent may be provided with much higher signal-to-noise ratio, call quality, and speech intelligibility.

[0035] Although shown and described as improving near-end speech intelligibility at a far- end participant of a telecommunications exchange, the noise-cancellation system 128 may be employed to improve near-end speech intelligibility at a far-end of any communications exchange. For instance, the noise-cancellation system 128 may be used in connection with virtual personal assistance (VPA) applications to optimize speech recognition at the far-end (i.e., a virtual personal assistant). Accordingly, background (unwanted) noise may be similarly suppressed or canceled from the near-end speech of a communications exchange with the VPA.

[0036] FIG. 3 is a simplified, exemplary flow diagram depicting a noise cancellation method

300 for far-end telecommunications. At step 305, near-end speech may be received at the noise cancellation system 128 by a microphone array, such as the first microphone array 124. Meanwhile, the noise cancellation system 128 may receive audio input streams from unwanted sources, such as unpredictable noise from the second microphone array 126 and/or predictable noise from the infotainment system 116, as provided at step 310. The near-end speech may be processed into an outgoing telecommunications signal 112b for receipt by a far-end participant of a telecommunications exchange. Accordingly, at step 315, the near-end speech signal may undergo an echo cancelling operation to improve voice quality by removing echo after it is already present. As previously described, echo cancellation involves first recognizing the originally transmitted signal that re-appears, with some delay, in the transmitted or received signal. Once the echo is recognized, it can be removed by subtracting it from the transmitted or received signal.

[0037] The near-end speech signal may be received at a noise suppressor along with the noise inputs received at step 310 and an incoming telecommunications signal for the far-end participant (step 320). During noise cancelling, the noise may be cancelled or suppressed from the near-end speech signal, as provided at step 325. At step 330, intelligibility of the speech in the near end speech signal may be restored by reducing or cancelling the effects of masking by extraneous sounds. The near-end speech signal may then undergo echo suppression using the incoming telecommunications signal, as provided at step 335. As previously described, echo suppression, like echo cancellation, is a method in telephony to improve voice quality by preventing echo from being created or removing it after it is already present. The near-end speech signal may undergo additional audio filtering at step 340 before it is transmitted to the far-end participant (step 345) via the telecommunications network as an outgoing telecommunications signal. Meanwhile, the incoming telecommunications signal may be played in the vehicle cabin through speakers (step 350).

[0038] FIG. 4 illustrates an exemplary microphone placement within the cabin 120 of the vehicle 104, according to one or more embodiments of the present disclosure. For example, a first microphone l24a, from the first microphone array 124, for picking up near-end speech may be embedded in one or more headrests 410. A second microphone l26a, from the second microphone array 126, for picking up noise may also be embedded in one or more headrests 410, a headliner (not shown), or the like. As shown, microphones positioned toward the inside of passengers with respect to the vehicle cabin 120, as near a user’s mouth as possible, may minimize the reflective energy in the signal, as compared to microphones positioned to the outside of passengers with respect to the vehicle cabin. This is because microphones positioned to the outside of passengers with respect to the vehicle cabin may receive more reflective energy from reflective surfaces 412, such as glass, enclosing the vehicle cabin 120. Minimizing the reflective energy in the near-end speech signal may increase speech intelligibility at the far-end of a telecommunication. The placement and/or location of the microphones shown in FIG. 4 is an example only. The exact location of the microphone arrays will depend on boundaries and coverage area inside a vehicle.

[0039] FIG. 5 illustrates an exemplary set-up for a headrest-based telecommunications system for a vehicle. A first, forward-facing microphone array 502 may be placed near a front 504 of a front passenger headrest 506 for receiving near-end speech of a telecommunications exchange. A second, rearward-facing microphone array 508 may be placed near a back 510 of the front passenger headrest 506 for receiving noise, including background speech. FIG. 6 illustrates another exemplary set-up for a headrest-based telecommunications system for a vehicle. A first, forward facing microphone array 602 may be placed near a front 604 of a front passenger headrest 606 for receiving near-end speech of a telecommunications exchange. A second, forward-facing microphone array 608 may be placed near a front 610 of a rear passenger headrest 612 for receiving noise, including background speech. As with FIG. 4, the exact location of the microphone arrays illustrated in FIGs. 5 and 6 will depend on boundaries and coverage area inside a vehicle.

[0040] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.