Matching and equalizing microphone output of an automotive microphone system

Abstract

A vehicle microphone system may include: at least two microphones that form a microphone array; at least one speaker configured to emit an audio signal; a processor coupled to a memory and programmed to: receive an incoming audio signal from the microphone array; determine at least one parameter for each channel of the microphone array; determine at least one filter to be applied to at least one channel based on a difference between the parameters for each channel; and store the at least one filter in the memory.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 955,171, filed on December 30, 2019, the disclosure of which is hereby incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to matching and equalizing microphone outputs of an automotive microphone system. Background Art

[0004] Vehicles include increasingly complex infotainment systems. These infotainment systems include various speakers, displays, etc. Current cabin acoustics use various signal - processing techniques to improve the user experience and audio quality. Such audio processing relies on input signals from vehicle microphones. Summary of the Invention

[0005] A vehicle microphone system may include: at least two microphones that form a microphone array; at least one speaker configured to emit an audio signal; a processor coupled to a memory and programmed to: receive incoming audio signals from the microphone array; determine at least one parameter for each channel of the microphone array; determine at least one filter to be applied to at least one channel based on a difference between the parameters of each channel; and store the at least one filter in the memory.

[0006] A method for reducing differences between microphone parameters within a vehicle microphone system may include: receiving incoming audio signals from a vehicle microphone array; determining at least one parameter for each channel of the microphone array; determining at least one filter to be applied to at least one channel based on a difference between the parameters of each channel; and storing the at least one filter in a memory.

[0007] A non - transitory computer - readable medium including instructions for reducing differences between microphone parameters within a vehicle microphone system includes: receiving incoming audio signals from a vehicle microphone array; determining at least one parameter for each channel of the microphone array; determining at least one filter to be applied to at least one channel based on a difference between the parameters of each channel; and storing the at least one filter in a memory. Brief Description of the Drawings

[0008] The embodiments of the present disclosure are specifically pointed out in the appended claims. However, other features of the various embodiments will become more apparent and best understood by referring to the following detailed description in conjunction with the accompanying drawings, in which:

[0009] Figure 1 An exemplary block diagram of an automotive microphone system is shown;

[0010] Figure 2 An exemplary block diagram of a microphone system is shown;

[0011] Figure 3 An exemplary block diagram of another microphone system is shown;

[0012] Figure 4 An exemplary block diagram of another microphone system is shown;

[0013] Figure 5 An exemplary block diagram of another microphone system is shown; and

[0014] Figure 6 An exemplary flowchart of a process for a microphone system is shown. DETAILED DESCRIPTION

[0015] In accordance with the requirements, detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the invention which may be embodied in various and alternative forms. The drawings are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.

[0016] Microphone arrays are becoming increasingly popular in automotive applications due to their superior performance in signal enhancement and noise suppression. The array can be used to create user satisfaction with the vehicle audio system. For example, the microphone array contributes to noise reduction functionality, directional sound experience, etc. However, due to the presence of multiple microphone elements in the array, parameter mismatches between the elements are typically a problem faced in achieving optimal acoustic array performance. A common microphone matching for microelectromechanical systems (MEMS) microphone designs is +-1 dB at 1 kHz. In order to be able to use more advanced algorithms, the elements must match better over the entire audio range (20 Hz to 20 kHz) and not just at 1 kHz. Such mismatches can reduce the effectiveness of certain audio processing features within the audio system.

[0017] Disclosed herein is an automotive microphone system design that includes a signal processing unit (e.g., CPU, DSP, FPGA) that can equalize and perform signal processing / filtering (filtering) within the microphone module. Through this processing, the microphone system output channels are equalized / matched. The described setup can also be used for single-element microphones to equalize the response. It can be used with both analog and digital microphones.

[0018] Manufacturing the described microphone system may require an end-of-line test setup where the microphone frequency response is measured, and based on the measured frequency response, the processing unit is set in the microphone module or the processor.

[0019] Step-by-step process at the end of the end-of-line test setup:

[0020] A pre-programmed microphone system with a bypass signal processing unit.

[0021] Measure the frequency response and phase of all channels of the microphone module.

[0022] Calculate the filters required for each microphone channel.

[0023] Reprogram the signal processing unit of the microphone module using the calculated filters.

[0024] Re-measure the frequency response and phase of all channels of the microphone module.

[0025] Figure 1 An exemplary block diagram of an automotive microphone system 100 of a vehicle 104 is shown. The microphone system 100 may include a telecommunications system 110 for processing incoming and outgoing telecommunications signals (collectively referred to as telecommunications signals 112 in Figure 1 ). The telecommunications system 110 may include a digital signal processor (DSP) 114 for processing audio telecommunications signals, as will be described in more detail below. According to another embodiment, the DSP 114 may be a module separate from the telecommunications system 110. The vehicle infotainment system 116 may be connected to the telecommunications system 110.

[0026] The first transducer 118 or speaker may transmit the incoming telecommunications signal to the proximal participant of the telecommunications switch within the passenger compartment 120. Thus, the first transducer 118 may be located adjacent to the proximal participant, or may generate a sound field at a specific seat position occupied by the proximal participant. The second transducer 122 may also transmit audio (e.g., music, sound effects, and dialogue from movie audio) from the vehicle infotainment system 116. The transducers 118, 122 may also transmit test signals or audio signals according to the instructions of the DSP 114 for audio system calibration, testing, and improvement.

[0027] At least one first microphone array 124 may be located in the passenger compartment 120 to receive sound from inside the passenger compartment 120. The sound may include ambient noise, such as road or wind noise, audio transmitted from the transducers 118, 122, the speech of the proximal participant (i.e., the driver or another passenger of the source vehicle), etc. The microphone array may include more than one microphone array. InFigure 1 In the example shown, two microphone arrays 124a, 124b may be included and more than two arrays 124 may be implemented. Signals from the microphone arrays 124 may be used for signal processing to improve the sound quality of the transducers 118, 122.

[0028] Figures 2 to 5 A block diagram of a microphone system is shown.

[0029] Figure 2 An exemplary block diagram of a microphone system 200 is shown. The microphone system 200 may include a microphone array 124 having a plurality of digital microphones 202. The microphones 202 may be directional microphones, omnidirectional microphones, or a combination of both. The microphones 202 may be digital microphones, such as Figure 2 in the example of, or the microphones 202 may be analog microphones. The microphones 202 may transmit audio signals to a processor 204. The processor 204 may be separate or may include a DSP 114 as shown in Figure 1 . The processor may also be a separate central processing unit (CPU), DSP, and / or field programmable gate array (FPGA). Additionally, Figure 1 the DSP 114 of may include a processor 204, a digital bus transceiver 206, and an EEPROM 208.

[0030] The processor 204 may transmit the audio signal to the digital bus transceiver 206, which in turn generates a digital signal. The digital bus transceiver 206 may be configured to receive the audio signal and transmit it to a digital data bus 210. The digital data bus 210 may then be configured to provide the signal back to the DSP 114 for further audio processing and to enhance the sound quality from the speaker 118.

[0031] The EEPROM 208 (also referred to herein as the memory 208) may be configured to provide filtering and filtering parameters and may communicate with the processor 204 and the digital bus transceiver 206. That is, the microphone elements may be analog and / or digital microphone elements. The signal processing unit may be a CPU or DSP or FPGA signal processor, etc. The output may be analog or digital. The EEPROM 208 may be used for filter configuration and may also be integrated in the signal processor 204. This is described in more detail below. Although the memory 208 is specifically described as an EEPROM, other non-volatile memories may also be used and implemented.

[0032] The microphone array 126 can receive audio signals across multiple microphone channels. These channels can receive signals with various parameters, characteristics, etc. These parameters can include frequency response, which includes amplitude and phase. When the microphone channel parameters are not aligned, the signal processing of the audio system may not perform optimally. Therefore, filters are created for each channel to prevent mismatches.

[0033] Figure 3 Another exemplary block diagram of a microphone system 300 is shown. Similar to Figure 2 , the microphone system 300 can include a microphone array 124 having a plurality of digital microphones 202 configured to transmit audio signals to a processor 204. The processor 204 can transmit the signal to a digital-to-analog converter 212, which in turn can convert the digital signal from the microphone 202 into an analog output. The EEPROM 208 can be configured to provide filtering and can communicate with the processor 204.

[0034] Figure 4 Another exemplary block diagram of a microphone system 400 is shown. A plurality of analog microphones 214 can transmit analog signals to an analog-to-digital converter 216. The converter 216 can convert the analog signal received from the microphone 214 into a digital signal. Then the digital signal from the converter 216 can be transmitted to the processor 204. Similar to the example in Figure 2 , the processor 204 can transmit the signal to a digital bus transceiver 206, which in turn generates a digital signal. The EEPROM 208 can be configured to provide filtering and can communicate with the processor 204 and the digital bus transceiver 206.

[0035] Figure 5 Another exemplary block diagram of a microphone system 500 is shown. Similar to Figure 4 , a plurality of analog microphones 214 can transmit analog signals to an analog-to-digital converter 216. Then the digital signal from the converter 216 can be transmitted to the processor 204. Similar to the example in Figure 2 , the processor 204 can transmit the signal to a digital-to-analog converter 212 to generate an analog signal. The EEPROM 208 can be configured to provide filtering and can communicate with the processor 204.

[0036] Figure 6 An exemplary flowchart of a process 600 for a microphone system 100 is shown. The process 600 can be executed by the DSP 114, the processor 204, or another general-purpose or special-purpose processor. The process 600 can begin at block 605, where the processor 204 can program the audio bypass signal to be emitted at the speakers 118, 122.

[0037] At block 610, the processor 204 may receive audio samples from the microphone array 126. The audio signal may include digital signals based on the bypass signal from each digital microphone 202.

[0038] At block 615, the processor 204 may determine parameters for each microphone channel of the microphone array 124, including frequency response and phase.

[0039] At block 620, the processor 204 may determine the filters required for each microphone channel. The filters may be determined for each specific channel based on the differences or mismatches between the frequency response and phase of each channel.

[0040] At block 625, the processor 204 may apply the filters to the corresponding microphone channels. The memory 208 may maintain these filters and apply the filters when an audio signal is received from the microphone array 124. The filters may make the specific frequency response and phase of the microphone channels more consistent. For example, instead of a typical MEMS design that matches at +-1dB at 1kHz, the filters may make the channels match across the entire audio range (e.g., 20Hz to 20kHz) and not just at 1kHz. The filters help equalize the microphone array 124 for better signal processing, which can result in better acoustic performance, noise reduction, etc.

[0041] At block 630, the processor 204 may determine parameters for each microphone channel of the microphone array 124 to which the filters have been applied, including frequency response and phase. That is, the processor 204 may re-measure the signal and determine the efficacy of the filters and determine whether the microphone channels are equalized or matched.

[0042] At block 635, the processor 204 may re-measure and determine whether the parameters of the microphone channels are equalized. This may be done by comparing the parameters of the channels and determining whether the frequency responses of the channels are within a certain threshold of each other. That is, the processor 204 may determine whether the amplitude and / or phase of one microphone channel is within a certain threshold difference from another microphone channel.

[0043] If the channel parameters are within a certain threshold of each other, the process 600 proceeds to block 640. If not, the process 600 proceeds to block 620 to further refine the filters for each channel. At block 640, the processor 204 may save the filters in the memory 208 for future application.

[0044] Accordingly, the present disclosure provides a vehicle microphone system that equalizes and aligns channel parameters of a microphone array. This is achieved by applying certain filters to certain channels based on the frequency response of the bypass signal on each channel. The microphone array may include digital or analog microphones, and their outputs may be analog or digital. Although the system is described for automotive applications, other applications such as home theater, surround sound, etc. may also benefit from the system, and the reference to vehicles is not intended to be limiting. The processes described herein may be end-of-line processes for the microphone array. This may be done at the test stage or even potentially at the installation stage. By applying filters at the processor 204, the microphone array 124 can be continuously updated with additional filters or filter parameters.

[0045] Any one or more of the controllers and processors or devices described herein include computer-executable instructions that may be compiled or interpreted from a computer program created using a variety of programming languages and / or technologies. Generally, a processor such as a microprocessor receives instructions from, for example, a memory, a computer-readable medium, etc. and executes the instructions. The processing unit includes a non-transitory computer-readable storage medium capable of executing the 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 semiconductor storage device, or any suitable combination thereof.

[0046] Although the exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. On the contrary, the words used in this specification are descriptive rather than restrictive words, and it should be understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implemented embodiments may be combined to form further embodiments of the invention.

Claims

1. A vehicle microphone system, comprising: At least two microphones, the at least two microphones forming a microphone array; At least one speaker, the at least one speaker being configured to emit an audio signal; A processor, the processor being coupled to a memory and programmed to: Receive an incoming audio signal from the microphone array; Determine at least one parameter of each channel of the microphone array; Determine at least one filter to be applied to at least one channel based on a difference between at least one of the parameters of each channel; Determine the parameters of each channel of the microphone array to which at least one filter is applied; Determine whether the parameters of the channels of the microphones of the microphone array are equalized; And If the parameters of the channels of the microphones of the microphone array are equalized, store the at least one filter in the memory; Wherein, the at least one parameter includes the frequency response and phase of each channel; Wherein, determining whether the parameters of the channels of the microphones of the microphone array are equalized includes: determining whether the amplitude and / or phase of one channel is within a specific threshold difference from another channel.

2. The system according to claim 1, wherein the at least one filter is configured to adjust the at least one parameter of the associated channel to reduce the difference between the at least one parameter of each channel.

3. The system according to claim 2, wherein the at least one parameter includes the frequency or phase of the associated channel.

4. The system according to claim 1, wherein the processor is further programmed to re-measure the at least one parameter of a subsequent audio signal after applying the at least one filter and to adjust the at least one filter based on the difference between the at least one parameter of the subsequent audio signal and the parameters of each of the other channels.

5. The system according to claim 1, wherein the microphone array includes a plurality of digital microphones.

6. The system according to claim 1, wherein the microphone array includes a plurality of analog microphones.

7. A method for reducing the difference between microphone parameters within a vehicle microphone system, comprising: Receive an incoming audio signal from a vehicle microphone array; Determine at least one parameter of each channel of the microphone array; Determine at least one filter to be applied to at least one of the channels based on a difference between the at least one parameter of each channel; Determine the parameters of each channel of the microphone array to which a filter is applied; Determine whether the parameters of the channels of the microphones of the microphone array are equalized; And If the parameters of the channels of the microphones of the microphone array are equalized, store the at least one filter in the memory; Wherein, the at least one parameter includes the frequency response and phase of each channel; Wherein, determining whether the parameters of the channels of the microphones of the microphone array are equalized includes: determining whether the amplitude and / or phase of one channel is within a specific threshold difference from another channel.

8. The method according to claim 7, wherein the at least one filter is configured to adjust the at least one parameter of the associated channel to reduce the difference between the at least one parameter of each channel.

9. The method according to claim 8, wherein the at least one parameter includes the frequency or phase of the associated channel.

10. The method according to claim 7, further comprising re-measuring the at least one parameter of a subsequent audio signal after applying the at least one filter, and adjusting the at least one filter based on the difference between the at least one parameter of the subsequent audio signal and the parameters of each of the other channels.

11. The method according to claim 7, wherein the microphone array includes a plurality of digital microphones.

12. The method according to claim 7, wherein the microphone array includes a plurality of analog microphones.

13. A non-transitory computer-readable medium including instructions for reducing the difference between microphone parameters within a vehicle microphone system, comprising: Receive an incoming audio signal from a vehicle microphone array; Determine at least one parameter of each channel of the microphone array; Determine at least one filter to be applied to at least one channel based on a difference between the at least one of the parameters of each channel; Determine the parameters of each channel of the microphone array to which a filter is applied; Determine whether the parameters of the channels of the microphones of the microphone array are equalized; And If the parameters of the channels of the microphones of the microphone array are equalized, store the at least one filter in the memory; Wherein, the at least one parameter includes the frequency response and phase of each channel; Wherein, determining whether the parameters of the channels of the microphones of the microphone array are equalized includes: determining whether the amplitude and / or phase of one channel is within a specific threshold difference from another channel.

14. The non-transitory computer-readable medium according to claim 13, wherein the at least one filter is configured to adjust the at least one parameter of the associated channel to reduce the difference between the at least one parameter of each channel.

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