Acoustic microphone arrays

Acoustic microphone array systems including arrays of microphones placed on a printed circuit board or other substrate in asymmetric patterns. A plurality of additional non-microphone components also reside on the board. The asymmetric placement of the microphones in the array provides flexibility in physically accommodating the additional non-microphone components.

BACKGROUND

The present disclosure relates generally to acoustic microphone systems incorporating an array of microphone elements.

SUMMARY

According to aspects of the disclosure, an acoustic microphone array system includes a substrate and an array of acoustic microphones. The array have a first group of acoustic microphones placed on the substrate in an asymmetric pattern and a second group of microphones. The radial distance of each microphone in the first group of microphones may be larger than the radial distance of each microphone in the second group of microphones. The substrate can be circular, or have a variety of other shapes, depending on the embodiment.

The second group of microphones can be placed on the substrate in an asymmetric pattern in some embodiments. In some implementations, the radial distance of an innermost microphone in the second group of microphones is no more than about 25% of a radial distance of an outermost microphone in the first group of microphones.

In some embodiments, the system further includes one or more packaged integrated circuits placed on the substrate at a radial distance greater than the radial distance of the innermost microphone in the second group and less than the radial distance of the outermost microphone in the first group. In further embodiments, the radial distance of an innermost microphone in the first group of microphones is no more than 50% of the radial distance of an outermost microphone in the first group of microphones. The packaged integrated circuits can be placed on the substrate at a radial distance between the radial distance of the innermost microphone in the first group of microphones and the radial distance of the outermost microphone in the first group of microphones.

The first group of microphones in some embodiments includes N microphones, and the maximum difference in polar angle between any two angularly adjacent microphones of the first group of microphones is at least 130% of 360/N. The system can further include a packaged integrated circuit placed between angularly adjacent microphones in the first group of microphones.

In some embodiments, the system includes a group of packaged integrated circuits mounted on the substrate together with the first and second groups of microphones. The group of packaged integrated circuits can include one or more networking devices and one or more microprocessors.

The system can further include a processor placed on the substrate and configured to perform one or both of acoustic echo cancelation and beamforming on signals output by the first and second groups of microphones.

The system can further include a processor configured to combine signals output by the first group of acoustic microphones to generate output sound within a first frequency range and to combine signals output by the second group of acoustic microphones to generate output sound within a second frequency range. The first and second frequency can, in some embodiments, cover a combined frequency that at least includes frequencies from 1,000 Hz to 14,000 Hz. A maximum frequency in the first frequency range can be substantially less than 14,000 Hz, and a minimum frequency of the second frequency range can be substantially more than 1,000 Hz.

According to some embodiments, the processor is remote from the first and second groups of microphones, and in communication with the first and second groups of microphones via a network.

According to further aspects of the disclosure, an audio system is provided that includes a substrate, an array of acoustic microphones, and a processor. The array can include a first group of acoustic microphones arranged on the substrate in an asymmetric pattern> The array may further include a second group of acoustic microphones arranged on the substrate in an asymmetric pattern. The radial distance of an innermost microphone of the first group of microphones from a center of the substrate may be greater than a radial distance of an outermost microphone of the second group of microphones and no more than about 40% of the radial distance of an outermost microphone of the first group of microphones. The radial distance of the outermost microphone in the second group of microphones may be no more than about 25% of the radial distance of the outermost microphone in the first group of microphones. The processor can be configured to combine signals output by the first group of acoustic microphones to generate output sound within a first frequency range and to combine signals output by the second group of acoustic microphones to generate output sound within a second frequency range. In some embodiments, the processor is remote from the first and second groups of microphones, and in communication with the first and second groups of microphones via a network.

According to yet further aspects of the disclosure, a method of generating a microphone layout for an array microphone is provided. The method can include placing each microphone in first and second groups of microphones in an arbitrary initial position on the substrate. Subsequent to said placing each microphone, the microphones can be arranged at an initial set of microphone positions.

The method can include, with a software simulator, determining array performance with the microphones at the initial set of microphone positions.

The method can also include, subsequent to said determining array performance, adjusting placement of one or more microphones in one or both of the first group of microphones and the second group of microphones such that the microphones are arranged at an adjusted set of microphone positions.

The method can additionally include, with the software simulator, determining adjusted array performance at the adjusted set of microphone positions. The method can further include repeating said adjusting placement and determining adjusted array performance said adjusted array performance indicates sufficient performance at a set of final microphone positions in which the first group of microphones is arranged in a first asymmetric pattern and the second group of microphones is arranged in a second asymmetric pattern.

The method can also include placing a plurality of non-microphone components on a substrate.

At the set of final microphone positions, each microphone in the first group may be located at a longer radial distance from the center of the substrate than each microphone in the second group.

The placing of the plurality of non-microphone components may be performed prior to said placing each microphone in the first and second groups of microphones in an initial position on the substrate.

DETAILED DESCRIPTION

System Overview

Audio processing systems include sophisticated computer-controlled equipment that receive and distribute sound in a space. Such equipment can be used in business establishments, bars, restaurants, conference rooms, concert halls, churches, or any other environment where it is desired to receive audio inputs from a source and deliver it to one or more speakers for people to hear. Some modern systems incorporate integrated audio, video, and control (AV&C) capability to provide an integrated system architecture. An example of such a system is the QSC® Q-SYS™ Ecosystem provided by QSC, LLC, which provides a scalable software-based platform. A simplified representation of an audio/video system100is shown and described with respect toFIG.1.

The system100includes a processing core120that includes one or more processors122, a network130, one or more microphone systems140, loudspeakers150, cameras160, control devices170, and third party devices180. The processor(s)122of the illustrated embodiment is a general purpose microprocessor, although alternative configurations can include an audio processor designed for audio digital signal processing.

The microphone systems140can include one or more array microphone systems, which can be any of the array microphone systems described herein including microphones mounted in an asymmetric array, although other types of microphone systems can also be included. The cameras160can include one or more digital video cameras. The control devices170can include any appropriate user input devices such as a touch screen, computer terminal or the like. While not shown inFIG.1, the system100can also include appropriate supporting componentry, such as one or more audio amplifiers or equalization components.

The third party devices180can include one or more laptops, desktops or other computers, smartphones or other mobile devices, projectors, screens, lights, curtains/shades, fans, and third party applications that can execute on such devices, including third party conferencing applications such as Zoom or Microsoft® Teams or digital voice assistants like Apple's Siri®.

While illustrated as separate components inFIG.1, depending on the implementation, microphone systems140, loudspeakers150, cameras160, control devices170, and/or third party devices180can be integrated together. For example, some or all of a microphone array, loudspeaker, camera, and touch screen can be integrated into a common packaging.

In operation, the microphone(s)140detect sounds in the environment, convert the sounds to digital audio signals, and stream the audio signals to the processing core120over the network130. The processor(s)122receives the audio signals and performs digital signal processing on the signals. For example, the processor122can perform fixed or adaptive echo cancellation, fixed or adaptive beamforming to enhance signals from one or more directions while suppressing noise and interference from other directions, amplification, or any combination thereof. Other types of noise processing, spatial filtering, or other audio processing can be performed depending on the embodiment. In some embodiments, instead of the microphone140sending raw digital audio signals to the processing core120, one or more processors on the microphone system140itself perform some or all of the echo cancellation, beamforming, amplification, or other processing prior to sending the signal to the processing core120.

As mentioned, the microphone system140can include one or more microphone arrays including a plurality of individual microphone elements. As these microphone arrays become more feature-rich, they include increasing numbers of not only microphone elements but other components (processors, sensors, electrical components, etc.), as will be described in more detail including with respect toFIGS.3A-3DandFIGS.5and6. However, existing microphone arrays such as those used for beamforming typically employ microphones arranged in rigidly defined geometries. These can include concentric rings, straight lines, squares, rectangles, or the like. As the number and sophistication of microphone components continues to increase, it can be difficult to physically accommodate rigidly defined microphone geometries together with the other components. Certain embodiments described herein address these and other challenges by allowing flexible microphone arrangements, freeing up real estate on the microphone board.

Microphone System

FIG.2shows a block diagram of an example of a microphone system140that can be used with the system100ofFIG.1or with any of the systems described herein. The microphone system140includes a housing200, a plurality of microphones202arranged in an asymmetric array, one or more discrete electrical components204, one or more integrated circuits206, one or more outputs208, one or more sensors210, one or more user interface components212, and one or more mounting or other hardware components214.

Some or all of the aforementioned components202-214can be mounted on one or more substrates or boards216, which can be printed circuit boards (PCBs) for example. The boards216can be contained, enclosed, or otherwise supported by the housing200, which can be a single-piece enclosure (e.g., a single-piece molded plastic), or a combination of pieces, such as a combination of molded plastic and perforated acoustic mesh to facilitate ingress and egress of incoming and outgoing sound. Depending on the embodiment, the microphone system140can be configured for placement or installation on or in a table-top, on or within a ceiling (e.g., to replace a ceiling panel), on or in a wall, or in some other desired location.

Examples of Asymmetric Microphone Systems

FIGS.3A-3Ddepict views of a top board216a(FIGS.3A-3B) and a bottom board216b(FIGS.3C-3D) of one example of microphone system140, where in an assembled configuration the top board216ais stacked on the bottom board216b, with the bottom of the top board216a(FIG.3B) facing the top of the bottom board216b(FIG.3C), and the stack is placed in a housing200(not shown inFIGS.3A-3D). In the illustrated embodiment top board216aand the bottom board316bare printed circuit boards (PCB) each having a diameter D of 11 cm, although other sizes are possible.

FIGS.3A-3Brespectively show top and bottom views of the top board216a. Referring toFIG.3B, a plurality of microphones202a-202pare mounted to the bottom of the top board216a. Referring toFIG.3A, the top board216aincludes a plurality of circular holes302each corresponding to, and exposing a portion of the underside of, a corresponding one of the microphones202a-202p. The holes302can facilitate detection of sound waves by the microphones204a-204pincident on the microphone system140from the top of the top board216athrough the housing200.

The microphones202a-202pof the embodiment illustrated inFIGS.3A-3Dare each omnidirectional piezo electric MEMS-based acoustic microphone transducers capable of detecting sound in a frequency range of 10 Hz to 20,000 Hz and a high linearity frequency range of 80 Hz to 8,000 Hz, and are housed in integrated circuit packages mounted on the top board216a. In other embodiments, other types of microphones can be used such as dynamic or condenser microphones.

The microphones202a-202pof the illustrated embodiment include a first group of nine microphones202a-202iand a second group of seven microphones202j-202p. The processor122can process and/or combine signals output from the first group of microphones202a-202ito generate sound content within a first frequency range, and process and/or combine signals output from the second group of microphones202j-202pto generate output sound content within a second frequency range.

For example, the processor122may filter signals output by the first group of microphones202a-202iusing one or more first filters (e.g., bandpass filters), and combine the filtered outputs to generate processed audio within the first frequency range, and filter signals output by the second group of microphones202j-202pusing one or more second filters (e.g., bandpass filters), and combine the filtered outputs to generate processed audio within the second frequency range.

The second frequency range according to some embodiments is higher than the first frequency range, although the frequency ranges can overlap somewhat. In some embodiments, the maximum frequency of the first frequency range and the minimum value of the second frequency range are values at which the first group and the second group have similar noise performance. A variety of possible values are possible for the first and second frequency ranges. Here just a few examples:

First Frequency Range (Hz)Second Frequency Range (Hz)20-1,2001,200-20,00080-1,2001,200-20,00020-2,0002,000-20,00080-2,0002,000-20,00020-3,0003,000-20,00080-3,0003,000-20,00080-,1,2001,200-8,00080-2,0002,000-8,00080-3,0003,000-8,000

While the examples provided indicate that the first and second frequency ranges overlap exactly at a single value (1,200, 2,000, or 3,000 Hz), in some embodiments the ranges can have larger overlaps, such as by 5, 10, 100, 1,000, 2,000, 3,000, 5,000 or more Hz, or by values between these amounts. Depending on the embodiment, the combined first and second frequency ranges can at least cover certain voice frequency bands, such as 300-3,400 Hz, 50-7,000 Hz, 50-14,000 Hz, or 20-20,000 Hz. The frequency range can be relatively broad to capture not only speech bandwidths, but other sounds for improved noise handling or other purposes.

As shown inFIGS.3A-3B, the microphones202a-202oof the illustrated embodiment (excluding the central microphone202p, which may not be included in some embodiments) are placed such that each microphone202a-202ois at a unique radial distance R and different polar angle P from a center of the substrate as compared to the other microphones in the array. In the illustrated embodiment, the top board216ahas a diameter of 11 cm, and the microphones are positioned at the following unique radial distances R and polar angles P from the center of the substrate:

The radial distance R and polar angle are measured from the center of the board216ato the center of the hole302(FIG.3A) of the corresponding microphone202, which also corresponds to the center of the package of each microphone202(FIG.3B). In other implementations, rather than each microphone having a unique polar angle from all other microphones in the array, each microphone in a particular group has a unique polar angle as compared to the other microphones in that group, but may share a polar angle with one or more microphones in another group. In yet further implementations, one or more microphones in a group may share a common radial distance with other microphones in that group.

The sparse, scattered arrangement of the microphones202a-202iin the first group can be helpful in accommodating additional componentry, particularly larger integrated circuits or other relatively large components. Variability in radial distances of microphones can help achieve this benefit.

For instance, in the illustrated embodiment, the radial distance of the innermost microphone202gin the first group is about 49% (2.42/4.92) of the radial distance of the outermost microphone202hin the first group, and about 44% (2.42/5.5) of the radius of the top board216a. In various implementations, the radial distance of the innermost microphone202gin the first group is no more than about 30, 35, 40, 45, 49, 50, 55, 60, or 70% of the radial distance of the outermost microphone202hin the first group, and/or of the radius of the board216.

Variability in polar angle of microphones in a group can also help achieve a sparse, scattered geometry to facilitate design flexibility. In a rigidly circular array, each microphone202in a group of nine microphones would be 40 degrees apart (360/9). In the illustrated embodiment, on the other hand, the maximum difference in polar angle between any two angularly adjacent microphones in the first group is between microphone202fand microphone202g, which are 55.71 degrees apart (about 139% [55.71/40] of the angular separation in a circular symmetric ring having the same number of microphones). In various implementations, the maximum difference in polar angle between any two angularly adjacent microphones in a group (e.g., an outer group, inner group, and/or a group of microphones for a particular frequency range) of N microphones is at least about 120, 130, 135, 140, 145, 150, 160, or 170% of 360/N.

The minimum difference in polar angle between any two angularly adjacent in the first group is between microphone202band microphone202c, which are 17 degrees apart (about 43% [17/40] of the angular separation in a circular symmetric array). In various implementations, the minimum difference in polar angle between any two angularly adjacent microphones in a group (e.g., an outer or inner group excluding a central microphone) of N microphones is no more than about 25, 30, 40, 45, 50, 55, 60, or 65% of 360/N).

The combination of a relatively compact inner group of microphones202j-202pand a sparse, scattered outer group202a-202ican also help accommodate additional componentry. For instance, in the illustrated embodiment, the radial distance of the outermost microphone202lin the relatively compact second group is 1.06 cm, or about 19% (1.06 cm/5.5 cm) of the radius of the top board216a, and about 21% (1.06 cm/4.92 cm) of the radial distance of the outermost microphone202hin the array. In various implementations, the radial distance of the outermost microphone202lin the second group is no more than about 10, 15, 20, 25, 30, or 35% of the radius of the board216a, or of the radial distance of the outermost microphone202hin the array, thereby maintaining a compact geometry for the second group.

The wide variability in microphone radial distance between groups creates additional space for mounting components. For example, the radial distance of the innermost microphone202min the relatively compact second group is 0.73 cm, or about 13% (0.73 cm/5.5 cm) of the radius of the top board216a, and about 15% (0.73 cm/4.92 cm) of the radial distance of the outermost microphone202hin the outer group. In various implementations, the radial distance of the innermost microphone202lin the second group is no more than about 5, 10, 15, 20, 25, or 30% of the radius of the board216a, or of the radial distance of the outermost microphone202hin the first group, thereby maintaining a compact geometry for the second group.

Referring now toFIG.3B, the bottom side of the top board216aaccommodates the microphones202a-202pas well as additional components. The additional components in the illustrated embodiment include: hardware214including three mounting holes304and corresponding periphery regions306configured to accept three PCB standoffs340a-340cof the bottom board216b(FIG.3B); integrated circuits206including i) a pulse density modulation to pulse code modulation to time domain multiplexed (PDM to PCM to TDM) converter and channel aggregator308afor format converting and aggregating audio signals output by the outer group of microphones202a-202i, ii) a second PDM to PCM to TDM converter and channel aggregator308bfor format converting and aggregating signals output by the inner group of microphones202j-202p, iii) a first clock distribution integrated circuit312afor sending clock signals to the first group of microphones202a-202i, and iv) a second clock distribution integrated circuit312bfor sending clock signals to the second group of microphones202j-202p; additional hardware214including a male board to board connector310for electrically connecting the bottom board216aand the top board216b(e.g., for routing PDM to PCM to TDM converted microphone signals to the bottom board216b); and a number of discrete electrical components including surface mount devices (SMDs) comprising inductors314, capacitors316, and resistors318; and a proximity sensor307, which can an optical sensor or other type of sensor be used to detect a user's hand over the microphone for temporary muting or other control purposes.

FIG.3Cillustrates a top view of the bottom board316a. Mounted on the top board316aof the illustrated embodiment are: hardware214including a female board-to-board connector330for connecting with the male connector310of the top board216a, and the PCB standoffs340a-340cfor spacing the two boards216a,216bwhen assembled; integrated circuits206including an SDRAM memory device332, a microprocessor334, an Ethernet switch336, and a power over Ethernet (POE) power controller342; user interface components including six LEDs338arranged around the periphery of the board216bto form a light ring; and discrete electrical components204including SMD inductors314, capacitors316, and resistors318.

Referring toFIG.3D, following components are mounted to the bottom of the bottom board216of the illustrated embodiment: hardware214including an Ethernet jack350for connecting to a network130and Ethernet magnetics352for isolating the Ethernet connection/componentry; discrete electrical components power supply transformer354, electrolytic capacitor356, MOSFET transistors358a-b; and integrated circuits206including the voltage controlled oscillator360. During operation, the microprocessor334can package detected audio signals to the Ethernet switch336aaccording to the Ethernet protocol for delivery to the network130over the Ethernet jack350.

In addition to providing improved flexibility for mounting components, asymmetric arrays can provide performance benefits. For example, having variable distances between the microphones in the array and reflective surfaces such as the outer case can prevent constructive interference, effectively spreading out and cancelling certain types of noise as compared to symmetric designs.

The plots shown inFIG.4illustrate performance of the microphone array40ofFIGS.3A-3D. As shown, the microphone system140ofFIGS.3A-3D, after beamforming and other appropriate processing by the processor122, achieves good directionality in detecting 500 Hz sound at 0/360 degrees (upper left quadrant), 90 degrees (lower left quadrant), 180 degrees (lower right quadrant), and 270 degrees (upper right quadrant), while maintaining a flexible, asymmetric microphone placement geometry. Because the cross-over frequency between the first and second groups of microphones202a-i,202j-pis about 1200 Hz, the plots primarily show performance of the first group202a-202i, which is used to detect sounds in a frequency range of about 20-1,200 Hz.

Single Board Embodiment Microphone System

While the embodiment ofFIGS.3A-3Dis a dual-board configuration, in some cases it can be desirable to have a single board implementation, where the microphones and additional componentry in the microphone system140is accommodated on a single board. This can be advantageous from a visual design stand-point because it allows a slim, sleek aesthetic, or for functional reasons by allowing the microphone system to fit into thinner, flatter form factors, such as for use in a ceiling tile or other space.

The design flexibility provided by the asymmetric microphone arrangements disclosed herein can be useful in enabling single-board implementations.FIG.5shows one example of a single board microphone system140. Mounted on the microphone board216are microphones202a-202parranged in a substantially similar arrangement to that of the embodiment ofFIGS.3A-3D, although different arrangements are possible. In addition, a large number of other components308-360are mounted on the board216. The components308-360can be the same as the like-numbered components inFIGS.3A-3D, although the system140ofFIG.5includes a second microprocessor334b.

As shown, the second microprocessor334bhas a rather large footprint, illustrating how the asymmetric microphone arrangement can physically accommodate components that a rigid symmetric array, such as an array of concentric rings, could not. In one embodiment, one or both of the microprocessors334a,334bimplement on-board fixed or adaptive acoustic echo cancellation, on-board fixed or adaptive beamforming, or both. Where echo cancellation and/or beamforming are performed on-board the microphone system140itself, one or both of the operations may be performed in the frequency domain, and the microprocessors334a,334bare programmed to perform time to frequency conversion and frequency to time conversion to convert the signals into the frequency domain for fixed or adaptive echo cancelation and/or fixed or adaptive beamforming, and back to the time domain for further processing. In other implementations, one of echo cancelation or beamforming is performed on-board in the frequency domain and the other is performed on-board in the time domain, and in yet further embodiments both are performed on-board in the time domain.

The combination of the compact second group of microphones202j-202pand the relatively sparse first group202a-202iallows for flexible placement of non-microphone components, including relatively large components like the second processor334band the Ethernet jack350. As shown, the radial distance of a number of the components (measured from the center of the board216to the center of the respective component package) is greater than the radial distance of the microphone in the second group202j-202pnearest to the component and less than the radial distance of the microphone in the first group202a-202inearest to the component (where “nearest” means the microphone having its center nearest to the center of the component package). As a few non-exhaustive examples: i) the radial distance of the microprocessor334ais greater than the radial distance of microphone202mand less than the radial distance of the microphone202d; ii) the radial distance of the power supply transformer354is greater than the radial distance of the microphone202oand less than the radial distance of the microphone202h; and iii) the radial distance of the voltage controlled oscillator360is greater than the radial distance of the microphone202land less than the radial distance of the microphone202c.

The relatively wide variability in radial distance between certain microphones in the outer group of microphones202a-202iprovides additional flexibility. For example, the components358band354are positioned in the space between the two microphones202g,202hin the outer group that have the largest difference in radial distance. Moreover, the relatively wide variability in angular separation between certain microphones in the outer group of microphones202a-202iprovides flexibility, evidenced by the placement of the relatively large Ethernet jack350between the microphones202f,202ghaving the largest angular separation of any two angularly adjacent microphones in the outer group202a-202i.

While certain embodiments have been shown for the purposes of illustration, other implementations are possible. For example, while the microphone boards216of the illustrated embodiments are circular, other shapes (rectangle, square, triangle, ovals, etc.) are possible in implementations. Moreover, while a particular arrangement of microphones has been shown, other arrangements are possible. For example, alternative implementations include arrangements in which the microphones within one or both the groups are placed at different locations, arrangements where there are more than two groups of microphones (e.g., three, four, five, or more groups), and/or arrangements where there are different numbers of microphones overall or within the groups. Moreover, there can be other numbers of microphones in other embodiments, including 4, 8, 20, 24, 32, 36, 48 or more microphones. For instance, where acoustic echo cancellation is performed on the microphone system140itself, 20, 32, 48 or more microphones can be included.

Microphone Array Construction

FIG.6is a flowchart showing an example of a method600of placing microphones asymmetrically in an array.

At step602, any non-microphone components are placed on the substrate. For example, a user can use a computer-aided design (CAD) software tool to place one or more integrated circuits, discrete electrical components, sensors, user interface components, physical hardware, or generally any of the additional components shown and/or described herein, e.g., with respect toFIGS.2,3A-3D, and5.

At step604, each microphone in a first group of microphones (e.g., the microphones202a-202i) are placed in an initial asymmetric arrangement in which each of the microphones has a unique polar angle and radius with respect to the center of a substrate. The placements may be selected by a user in a software design and/or simulation tool, or be automatically selected by a computer (e.g., using an algorithm involving a pseudorandom number generator). Whether manual or by computer, the placements can in some embodiments be arbitrarily selected but within certain constraints. For example, radius may be selected from a set of available radiuses between a certain minimum radius and a certain maximum radius. Moreover, the microphones cannot be placed where one of the additional non-microphone components were placed in step602. A further constraint may require that the radiuses and/or the polar angles satisfy some distribution profile within the range of possible values (e.g., at least some percentage of the microphones in the first group between each of 0 and 90, 90 and 180, 180 and 270, and 270 and 360 degrees).

At step606, each microphone in a second group of microphones (e.g., the microphones202j-202n) are placed in an initial asymmetric arrangement in which each of the microphones has a unique polar angle and radius with respect to the center of a substrate. The placement can be made in substantially the same fashion as for the first group, but with different constraints (e.g., smaller minimum radius and smaller maximum radiuses to select from).

At step608, microphone performance is simulated at the initial placements. For example, the user may place the microphones using a software design tool, export the initial microphone placements to a software simulation tool, and simulate beamforming or other performance metrics at the initial microphone placements using the simulation tool.

At step610, one or more of the microphones in the first and/or second group can be moved to an adjusted location. For example, a user may review performance a particular frequency range, and based on the review, adjust the placement of one or more of the microphones in the design tool to a location on the substrate that should provide improved performance in that frequency range.

At step612, microphone performance is again simulated and reviewed to determine whether sufficient array performance has been achieved. Steps610and612can be iterated to adjust placement of the microphones until sufficient array performance is observed.

In alternative embodiments, placement of the non-microphone components at step602can be performed after placement of the microphones (after steps604-612). Where step602is performed after placement of the microphones, if there is not an adequate empty space on the substrate to place an additional component (e.g., a relatively large IC) after placement of the microphones, steps610-612may need to be iterated to move one or more of the microphones and free up space for the additional component.

Moreover, where step602is performed before placement of the microphones, it could be the case that no placement of the microphones can be found that provides sufficient array performance. In this circumstance, the initial placement of one more of the additional components can be adjusted before moving the microphones further to find a microphone placement that provides sufficient performance.

Once final microphone placements are found, the final placements are recorded and/or output at step614, e.g., by the software design tool. The microphone system can then be fabricated using the output, by physically mounting the microphones on the PCB(s) according to the output obtained at step614.

Depending on the embodiment, certain acts, events, or functions of any of the methods described herein can be performed in a different sequence, can be added, merged, or left out altogether (e.g., not all described acts or events are necessary for the practice of the method). Moreover, in certain embodiments, acts or events can be performed concurrently, e.g., through multi-threaded processing, interrupt processing, or multiple processors or processor cores, rather than sequentially.