HK1251109B - Array microphone system and method of assembling the same - Google Patents

Description

Array microphone system and assembly method thereof

Cross-reference to related applications

This application claims the benefit of U.S. Patent Application No. 14/701,376, filed April 30, 2015, which is incorporated herein in its entirety.

Technical Field

The present application generally relates to an array microphone system and method of assembling the same. In particular, the present application relates to an array microphone that can be fitted into a ceiling tile of a suspended ceiling and provides 360-degree audio pickup with an overall directivity index optimized across the speech frequency range.

Background Art

Meeting environments, such as board meetings, video conferencing scenarios, and the like, may involve the use of microphones to capture sound from an audio source. For example, the audio source may include a human speaker. The captured sound may be transmitted to an audience via the speaker in the environment, a television broadcast, and/or a webcast.

In some embodiments, a microphone may be placed on a table or podium near the audio source to capture sound. However, such a microphone may be obtrusive or undesirable due to the size of the microphone and/or the aesthetics of the environment in which it is used. Additionally, a microphone placed on a table may detect undesirable noises, such as the tapping of a pen or the shuffling of paper. A microphone placed on a table may also be covered or blocked, for example, by paper, cloth, or tissue paper, preventing proper or optimal capture of sound.

In other environments, the microphone may include a shotgun microphone that is primarily sensitive to sounds in one direction. The shotgun microphone may be positioned away from the audio source and directed to detect sounds from a specific audio source by pointing the microphone toward the area occupied by the audio source. However, determining the direction to point the shotgun microphone to optimally detect sounds from its audio source can be difficult and tedious. Trial and error may be required to adjust the position of the shotgun microphone for optimal detection of sounds from the audio source. Thus, unless and until the position of the microphone is properly adjusted, sound from the audio source may not be ideally detected. And even if the position of the microphone is properly adjusted, audio detection may be unsatisfactory if the audio source moves in and out of the microphone's pickup range (for example, if a human speaker shifts their seat while speaking).

In some environments, microphones can be mounted to the ceiling or walls of a conference room to free up table space and allow human speakers to move freely around the room, thereby addressing at least some of the above concerns regarding tabletop and shotgun microphones. Most existing ceiling-mounted microphones are configured to be fastened directly to the ceiling or suspended from a drop-down cable mounted to the ceiling. Consequently, these products require complex installation and are intended to be permanent fixtures. Furthermore, while ceiling microphones may not pick up table noise due to their distance from the table, such microphones present their own audio pickup challenges due to their close proximity to speakers and HVAC systems, their greater distance from the audio source, and their increased sensitivity to air movement or white noise.

Therefore, an opportunity exists for a system that addresses these concerns. More specifically, an opportunity exists to implement a system that includes an array microphone that is unobtrusive, easily installed into existing environments, and that can enable the microphone array to be adjusted to optimally detect sound from an audio source (e.g., a human speaker) and suppress undesirable noise and reflections.

Summary of the Invention

The present invention seeks to solve the problems set forth above by, inter alia, providing systems and methods designed to: (1) provide an array microphone assembly sized and shaped to be installed in a suspended ceiling in place of a ceiling tile; and (2) provide an array microphone system comprising a concentric configuration of microphones that achieves improved directional sensitivity in the acoustic frequency range and an optimal main-to-sidelobe ratio in a specified range of steering angles.

In an embodiment, an array microphone system includes a substrate and a plurality of microphones arranged on the substrate into a plurality of concentric nested rings of varying sizes. In the embodiment, each ring includes a subset of the plurality of microphones positioned at predetermined intervals along the circumference of the ring.

In another embodiment, a microphone assembly includes an array microphone comprising a plurality of microphones and a housing configured to support the array microphone. In this embodiment, the housing is sized and shaped to be mountable in a suspended ceiling, replacing at least one of a plurality of ceiling tiles included in the suspended ceiling. Furthermore, a front face of the housing includes an acoustically permeable screen having a size and shape substantially similar to that of the at least one of the plurality of ceiling tiles.

In another embodiment, a method of assembling an array microphone includes: arranging a first plurality of microphones to form a first configuration on a substrate; and arranging a second plurality of microphones to form a second configuration on the substrate, wherein the second configuration concentrically surrounds the first configuration. The method further includes electrically coupling each of the first and second plurality of microphones to an audio processor for processing audio signals captured by the microphones.

These and other embodiments and various arrangements and aspects will be apparent and more fully understood from the following detailed description and accompanying drawings, which set forth illustrative embodiments that are indicative of the various ways in which the principles of the invention may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front perspective view of an exemplary array microphone assembly, in accordance with certain embodiments.

2 is a rear perspective view of the array microphone assembly of FIG. 1 , according to some embodiments.

3 is an exploded view of the array microphone assembly of FIG. 1 , according to some embodiments.

4 is a side cross-sectional view of the array microphone assembly of FIG. 3 , according to some embodiments.

5 is a top plan view of an array microphone included in the array microphone assembly of FIG. 3 , according to some embodiments.

FIG. 6 is an exemplary environment including the array microphone assembly of FIG. 1 , according to certain embodiments.

7 is another exemplary environment including the array microphone assembly of FIG. 2 , according to certain embodiments.

8 is another exemplary environment including the array microphone assembly of FIG. 2 , according to certain embodiments.

9 is a diagram showing microphone placement in another example microphone array, according to certain embodiments.

10 is a block diagram depicting an example array microphone system, in accordance with certain embodiments.

11 is a polar plot showing selected polar responses of the array microphone of FIG. 9 , according to certain embodiments.

12 is a flow chart illustrating an example process for assembling an array microphone, according to certain embodiments.

DETAILED DESCRIPTION

The following description describes, illustrates, and exemplifies one or more specific embodiments of the present invention in accordance with the principles of the present invention. This description is not provided to limit the invention to the embodiments described herein, but rather to explain and teach the principles of the present invention in such a way that a person skilled in the art can understand these principles and, with the aid of such understanding, can apply such understanding to practice not only the embodiments described herein but also other embodiments conceivable in accordance with these principles. The scope of the present invention is intended to encompass all such embodiments that may fall within the scope of the appended claims (either literally or in the doctrine of equivalents).

It should be noted that in the detailed description and drawings, the same reference numerals may be used to identify identical or substantially similar elements. However, different numbers may sometimes be used to identify these elements, such as, for example, where such identification facilitates a clearer description. In addition, the drawings set forth herein are not necessarily drawn to scale, and in some instances, proportions may be exaggerated to more clearly depict certain features. Such identification and diagrammatic practice do not necessarily indicate an underlying actual purpose. As stated above, the specification is intended to be considered as a whole and to be interpreted in accordance with the principles of the present invention as taught herein and as understood by those of ordinary skill in the art.

With respect to the exemplary systems, components, and architectures described and illustrated herein, it should be understood that embodiments may be embodied by or employed in a number of configurations and components, including one or more system, hardware, software, or firmware configurations or components, or any combination thereof, as understood by one of ordinary skill in the art. Thus, while the figures illustrate exemplary systems that include components for one or more of the embodiments contemplated herein, it should be understood that one or more components may not be present or necessary in the system with respect to each embodiment.

Provided herein are systems and methods for an array microphone assembly that (1) is configured to be mountable in a suspended ceiling in, for example, a conference or boardroom environment to replace an existing ceiling, and (2) includes a plurality of microphone transducers selectively positioned in a self-similar or fractal-like configuration or constellation to produce a high-performance array with, for example, an optimal directivity index and a maximum main-to-sidelobe ratio. In an embodiment, this physical configuration can be achieved by arranging the microphones in concentric rings, which allows the array microphone to have equivalent beamwidth performance at any given viewing angle in a three-dimensional (e.g., X-Y-Z) space. Thus, the array microphone described herein can provide a more consistent output than array microphones with linear, rectangular, or square constellations. Furthermore, given that the array microphone reduces sidelobes compared to existing arrays with collinearly positioned elements, each concentric ring within the microphone's constellation can have a slight rotational offset from every other ring to minimize sidelobe growth. This offset configuration can also allow for further beam steering, which allows the array to cover a wider pickup area. Furthermore, microphone constellations can be harmonically nested to optimize beamwidth within a given set of different frequency bands.

In embodiments, an array microphone may be capable of achieving maximum sidelobe suppression across a wide range of speech frequency ranges and array focus angles (e.g., viewing angles), at least in part due to the use of microelectromechanical systems (MEMS) microphones, which allow for greater microphone density and improved vibration noise suppression compared to existing arrays. The microphone density of the array constellation may allow for variable beamwidth control, whereas existing arrays are limited to fixed beamwidths. In other embodiments, the microphone system may be implemented using alternative transduction schemes (e.g., capacitors, balanced armatures, etc.) while maintaining microphone density.

1-5 illustrate an exemplary microphone array assembly 100 including a housing 102 and an array microphone 104, according to an embodiment. More specifically, FIG1 depicts a front perspective view of the microphone array assembly 100; FIG2 depicts a rear perspective view of the microphone array assembly 100; FIG3 depicts an exploded view of the microphone array assembly 100, showing various components of the housing 102 and the microphone array 104 contained therein; FIG4 depicts a side cross-sectional view of the microphone array assembly 100, according to an embodiment, and FIG5 depicts the microphone array 104. For purposes of simplicity and illustration, some structural support elements, such as screws, washers, the rear mounting plate 101, and the cable mounting hooks 103, and the standoffs 105, have been at least partially removed from selected views (e.g., FIG3-5).

Array microphone 104 (also referred to herein as a "microphone array") includes multiple microphone transducers 106 (also referred to herein as "microphones") configured to detect and capture sounds in the environment (e.g., speech emanating from speakers sitting in chairs around a conference table). Sound travels from an audio source (e.g., a human speaker) to microphones 106. In some embodiments, microphones 106 may be unidirectional microphones that are primarily sensitive to one direction. In other embodiments, microphones 106 may have other directivity or polar patterns, such as cardioid, sub-cardioid, or omnidirectional, as desired.

Microphone 106 can be any suitable type of transducer that can detect sound from an audio source and convert the sound into an electrical audio signal. In a preferred embodiment, microphone 106 is a microelectromechanical system (MEMS) microphone. In other embodiments, microphone 106 can be a condenser microphone, a balanced armature microphone, an electret microphone, a dynamic microphone, and/or other types of microphones.

Microphone 106 may be coupled to or included on substrate 107. In the case of a MEMS microphone, substrate 107 may be one or more printed circuit boards (also referred to herein as "microphone PCBs"). For example, in FIG5 , microphone 106 is surface-mounted to microphone PCB 107 and included in a single plane. In other embodiments, such as where microphone 106 is a condenser microphone, substrate 107 may be made of carbon fiber or other suitable materials.

1 and 2 , the housing 102 is configured to completely enclose the microphone array 104 to protect and structurally support the array 104. More specifically, a first side or front of the housing 102 includes an acoustically permeable screen or grille 108, and a second side or back of the housing 102 includes a backplate or support 110. As shown in FIG1 , the screen 108 may have a perforated surface including a plurality of small openings and may be made of aluminum, plastic, wire mesh, or other suitable material. In other embodiments, the screen 108 may have a substantially solid surface made of an acoustically permeable membrane or fabric. As shown in FIG3 , the housing 102 also includes a diaphragm 111 made of foam or other suitable material and positioned between the screen 108 and the microphone array 104 to protect the microphone array 104 from external elements, as will be appreciated by those skilled in the relevant art. 3 , the housing 102 further includes side rails 112 for securing the back support 110, foam membrane 111, and each side of the screen 108 together to form the housing 102. The housing 102 may further include a standoff 105 and spacers (not shown) to mechanically support the microphone assembly 104 away from the housing 102 and/or other components of the assembly 100.

6 , which shows an example ceiling 600 in which the microphone array assembly 100 is mounted. The ceiling 600 may be part of a meeting environment, such as, for example, a board meeting where microphones are used to capture sounds from an audio source or human speaker. In the exemplary environment of FIG6 , a human speaker (not shown) may be seated in a chair at a table below the ceiling 600 (or, more specifically, below the microphone array assembly 100), although other physical configurations and placements of the audio source and/or microphone array assembly 100 are contemplated or possible. In embodiments, the microphone array 104 may be configured to achieve optimal performance at a specific height or range of heights above the floor of the environment, for example, according to a standard ceiling height (e.g., eight to ten feet high) or any other suitable height range.

As shown in FIG6 , ceiling 600 can be a suspended ceiling (also known as a dropped ceiling or suspended ceiling) or a secondary ceiling suspended below the main structural ceiling. As is conventional, suspended ceiling 600 includes a grid of metal channels 602 suspended from the main ceiling on wires (not shown) and forming a pattern of regularly spaced cells. Each cell can be filled with a lightweight ceiling tile or panel 604 that can be removed, for example, to provide access to the area above the tile for repair or inspection. In a preferred embodiment, ceiling tiles 604 are recessed tiles that can be easily installed or removed without interfering with the grid or other tiles 604. Each ceiling tile 604 is typically sized and shaped according to the grid's "cell size." For example, in the United States, the cell size is typically approximately two feet by two feet square or approximately two feet by four feet rectangular. As another example, in Europe, the cell size is typically approximately 600 millimeters (mm) by 600 mm square. As another example, in Asia, the cell size is typically approximately 625 mm by 625 mm square.

In one embodiment, the housing 102 can be sized and shaped to be installed in the suspended ceiling 600 in place of at least one of the ceiling tiles 604. For example, the housing 102 can have length and width dimensions substantially equivalent to the unit size of the grid forming the suspended ceiling 600. In one embodiment, the housing 102 is substantially square, approximately two feet by two feet in size (e.g., each of the side rails 112 is approximately two feet long), such that the housing 102 can replace any one of the ceiling tiles 604 in a standard American suspended ceiling. In other embodiments, the housing 102 can be sized and shaped to replace two or more of the ceiling tiles 604. For example, the housing 102 can be shaped approximately four feet by four feet square, replacing any group of four adjacent ceiling tiles 604 forming a square. In other embodiments, the housing 102 can be sized to fit into a standard European suspended ceiling (e.g., 600 mm by 600 mm) or a standard Asian suspended ceiling (e.g., 625 mm by 625 mm). By installing the microphone array assembly 100 in place of the ceiling tiles 604 of the suspended ceiling 600 (similar to installing a speaker in a speaker enclosure, such as an infinite baffle, for example), the assembly 100 may gain acoustic advantages.

In some cases, an adapter frame (not shown) can be provided to modify or adapt the housing 102 so that it is compatible with suspended ceilings having unit sizes that are larger than the housing 102. For example, the adapter frame can be an aluminum frame that can be coupled around the periphery of the housing 102 and has a width that extends the dimensions of the housing 102 to accommodate a predetermined unit size. In such cases, a housing 102 sized for a standard American ceiling can be adapted to accommodate, for example, a standard Asian ceiling. In other cases, the housing 102 can be designed to accommodate a minimum unit size (e.g., 600 mm by 600 mm square), and the adapter frame can be provided as needed to extend the dimensions of the housing 102 to accommodate a variety of different unit sizes (e.g., two feet by two feet square, 625 mm by 625 mm square, etc.).

In embodiments, all or part of the housing 102 may be made of a lightweight, strong aluminum material or any other material that is light enough to allow the microphone array assembly 100 to be supported by the grid of the ceiling 600 and strong enough to enable the housing 102 to support the microphone array 104 mounted therein. For example, in certain embodiments, at least the back panel 110 comprises a flat, aerospace-grade aluminum sheet that includes a honeycomb core (e.g., as manufactured by). Furthermore, according to certain embodiments, the components of the housing 102 (e.g., side rails 112, back portion 110, screen 108, microphone array 104, etc.) may be configured to easily snap together for assembly and easily snap apart for disassembly. This feature allows the housing 102 to be customized according to the specific needs of the end user, including: (for example) replacing the screen 108 with a different material (e.g., fabric) or color (e.g., to match the color of the ceiling tiles 604); adding or removing adapter frames to change the overall size of the housing 102, as described above; replacing the side rails 112 to match the color or material of the metal channel 602 in the ceiling 600; replacing or adjusting the array microphone 104 (e.g., to provide an array with more or fewer microphones 106); and so on.

With additional reference to Figures 7 and 8, in embodiments, the housing 102 can be configured to provide alternative mounting options, for example, to accommodate environments having a ceiling 700 that is not a suspended ceiling. In some cases, the microphone array assembly 100 can include a rear mounting plate 101, as shown in Figure 2. The rear mounting plate 101 can be coupled to a mounting post 702 using a standard VESA mounting hole pattern, which is configured to attach to the ceiling 700, as shown in Figure 7. As shown in Figure 8, in some cases, the microphone array assembly 100 can be mounted to the ceiling 700 by coupling a drop-down ceiling cable 704 to a cable mounting hook 103, which is attached to the back support 110 of the housing 102, as shown in Figure 2. In other embodiments, the housing 102 can be configured to provide a wall mounting option and/or be placed in front of a performance area, such as a stage.

Referring now to Figures 2-4, the microphone array assembly 100 includes a control box 114 mounted on a back support 110. As shown in Figures 3 and 4, the control box 114 contains a printed circuit board 116 (also referred to herein as an "audio PCB") that is electrically coupled to the microphone array 104. For example, the audio PCB 116 can be coupled to the microphone array 104, or more specifically, to the substrate 107, via a board-to-board connector 118 that extends vertically from the microphone array 104 through an opening 120 in the back support 110, as shown in Figures 3 and 4. In an embodiment, the audio PCB 116 can be configured as an audio processor (e.g., via hardware and/or software elements) to process audio signals received from and captured by the microphone array 104 and generate corresponding audio outputs, as discussed in greater detail herein. As illustrated, the control box 114 can include a removable cover 122 to provide access to the audio PCB 116 and/or other components within the control box 114.

In an embodiment, the microphone array assembly 100 includes an external port 124 that is mechanically coupled to the control box 114 and is configured to electrically couple a cable (not shown) to the audio PCB 116. The cable can be a data, audio, and/or power cable, depending on the type of information being passed through the port 124. For example, after coupling the cable to the external port 124 of the audio PCB 116, the external port 124 can be configured to receive control signals from an external control device (e.g., an audio mixer, an audio recorder/amplifier, a conference processor, a bridge, etc.) and provide the control signals to the audio PCB 116. Furthermore, the port 124 can be configured to transmit or output audio signals received from the microphone array 104 at the audio PCB 116 to the external control device. In some cases, the external port 124 can be configured to provide power from an external power supply (e.g., a battery, a wall outlet, etc.) to the audio PCB 116 and/or the microphone array 104. In a preferred embodiment, the external port 124 is an Ethernet port configured to receive an Ethernet cable (e.g., CAT5, CAT6, etc.) and provide power, audio, and control connectivity to the microphone array assembly 100. In other embodiments, the external port 124 may include several ports and/or may include any other type of data, audio, and/or power port, including, for example, a Universal Serial Bus (USB) port, a mini-USB port, a PS/2 port, an HDMI port, a serial port, a VGA port, and the like.

Referring now to Figures 1 and 3, the microphone array assembly 100 further includes an indicator 126 that visually indicates the operating mode or status of the microphone array 104 (e.g., powered on, powered off, muted, audio detected, etc.). As shown in Figure 1, the indicator 126 may be integrated into the screen 108 so that it is visible on the exterior of the front of the housing 102 to externally indicate the operating mode of the microphone array 104 to human speakers or others in the conference environment. In one embodiment, the indicator 126 (also referred to herein as an "external indicator") includes at least one light source (not shown), such as a light emitting diode (LED), that turns on or off depending on the operating mode of the array microphone assembly 100 (e.g., powered on or off). In some embodiments, the light indicator 126 may turn on a first light source to indicate a first operating mode of the microphone array assembly 100 (e.g., powered on) and a second light source to indicate a second operating mode (e.g., audio detected), such that, in some examples, both light sources may be turned on simultaneously. In a preferred embodiment, the indicator 126 includes at least one LED (not shown) mounted to a PCB 126a (also referred to herein as an "LED PCB") and a light guide 126b configured to optically guide light from the LED out of the screen 108, as shown in Figure 3. The LED can be electrically coupled to the microphone array 104 via a cable 128 connecting the LED PCB 126a to a connector 129 on the microphone PCB 107, as shown in Figures 3 and 5.

Referring now to Figures 3 and 5, in an embodiment, the substrate 107 of the microphone array assembly 100 may include a central PCB 107a and one or more peripheral PCBs 107b positioned around the central PCB to increase the available space for mounting the microphones 106. For example, a portion of the microphone 106 may be mounted on the central PCB 107a and the remaining portion of the microphone 106 may be mounted on the peripheral PCBs 107b, as will be explained in more detail below. Each of the peripheral PCBs 107b may be coupled to the central PCB 107a using one or more board-to-board connectors 130. In a preferred embodiment, the microphones 106 are all mounted in one plane of the substrate 107, as shown in Figure 4.

The number, size, and shape of the one or more peripheral PCBs 107b can vary depending on, for example, the number of sides 130, the size and/or shape of the central PCB 107a, and the overall shape of the substrate 107. For example, in the illustrated embodiment, the central PCB 107a is a polygon with seven consistent sides 132, and the substrate 107 includes seven peripheral PCBs 107b, respectively coupled to each side 132 at an inner end 134 of each peripheral PCB 107b. As illustrated, the inner end 134 is a flat surface that is uniformly sized to match any of the seven sides 132. Each peripheral PCB 107b may further include an outer end 136 opposite the inner end 134. In the illustrated embodiment, the substrate 107 is shaped as a circle, and thus the outer end 136 of each peripheral PCB 107b is curved.

In other embodiments, the central PCB 107a may have other overall shapes, including, for example, other types of polygons (e.g., squares, rectangles, triangles, pentagons, etc.), circles, or ovals. In such cases, the inner ends 134 of the peripheral PCBs 107b may be sized and shaped according to the size and shape of the sides 132 of the central PCB 107a. For example, in one embodiment, the central PCB 107 may have a circular shape such that each of the sides 132 is curved, and thus the inner ends 134 of the peripheral PCBs 107b may also be curved. Similarly, in other embodiments, the substrate 107 may have other overall shapes, including, for example, ovals or polygons, and the outer ends 136 of the peripheral PCBs 107b may be shaped accordingly. In other embodiments, the substrate 107 may include a donut-shaped peripheral PCB 107b surrounding the circular central PCB 107a, or a single, continuous board 107 that includes all of the microphone transducers 106.

As shown in FIG5 , in an embodiment, the plurality of microphones 106 include a central microphone 106a positioned at the center point of a central PCB 107a and a combination of microphones 106b arranged in a fractal or self-similar configuration surrounding the central microphone 106a and positioned on either the central PCB 107a or the peripheral PCBs 107b. Due at least in part to the fractal-like placement of the microphones 106, the array microphone 104 can achieve improved directional sensitivity across the speech frequency range and a maximum main-to-sidelobe ratio within a specified steering angle range. Consequently, the microphone array 104 can more accurately "hear" signals from a single direction and suppress unwanted noise and/or interfering sounds, and can more effectively distinguish between adjacent human speakers. Furthermore, the fractal nature of the microphone configuration allows the directivity of the array 104 to be easily extended to a wider frequency range (e.g., lower and/or higher frequencies) by adding more microphones and/or creating a larger microphone array 104.

More specifically, in an embodiment, the microphones 106 may be arranged as concentric circular rings of varying sizes to avoid undesirable pickup modes (e.g., due to grating lobes) and accommodate a wide range of audio frequencies. As used herein, the term "ring" may include any type of circular configuration (e.g., perfect circle, nearly perfect circle, barely perfect circle, etc.), as well as any type of elliptical configuration or other elliptical ring. As shown in FIG5 , the rings may be positioned at various radial distances from the center microphone 106 a or the center point of the substrate 107 to form a nested configuration that can handle progressively lower audio frequencies, with the outermost ring configured to optimally operate at the lowest frequency in a predetermined operating range. Concentric rings can be used to cover specific frequency bands within a range of operating frequencies by using harmonic nesting techniques.

In an embodiment, each ring contains a different subset of the remaining microphones 106b, and each subset of microphones 106b may be positioned at predetermined intervals along the circumference of the corresponding ring. The predetermined spacing or spacing between adjacent microphones 106b within a given ring may depend on the size or diameter of the ring, the number of microphones 106b included in the subset assigned to the ring, and/or the desired sensitivity or total sound pressure of the microphones 106b in the ring. Increasing the number of microphones 106 and the microphone density of the rings (e.g., due to nesting of the rings) may help remove grating lobes and thereby produce an improved beamwidth with a near-constant frequency response across all frequencies within a preset range.

As will be appreciated, FIG5 shows only an exemplary embodiment of an array microphone 104, and other configurations of microphones 106 are contemplated according to the principles disclosed herein. For example, in some embodiments, the plurality of microphones 106 may be arranged in concentric rings around a center point, but no microphone is positioned at the center point (e.g., there is no center microphone 106a). In other embodiments, only some of the microphones 106 may be arranged in concentric rings, and the remainder of the microphones 106 may be positioned at various points outside or between discrete rings, at random locations on the substrate 107, or in any other suitable arrangement.

FIG9 diagrammatically depicts an exemplary microphone configuration 900 that may be present in an array microphone according to certain embodiments. Microphone configuration 900 may be substantially similar to the self-similar configuration of microphones 106 included in microphone array 104, except for the number of microphones 106 b included in the innermost ring of array 104. As shown, microphone configuration 900 includes one microphone 902 (e.g., center microphone 106 a) positioned at the center of configuration 900 and multiple microphones 906 (e.g., the remaining combinations of microphones 106 b) arranged in seven concentric rings 910 through 922. For ease of explanation and illustration, a circle is drawn through each group of microphones 906 forming a ring of microphone configuration 900.

To accommodate the microphone 906, the microphone arrangement 900 may be mounted on a plurality of printed circuit boards (not shown), similar to the central PCB 107a and the plurality of peripheral PCBs 107b. 5 , the microphones 906 may include: (i) a first subset of microphones 902 mounted on the central PCB 107 a to form a first ring 910 surrounding the central microphone 906; (ii) a second subset of microphones 906 mounted on the central PCB 107 a to form a second ring 912 surrounding the first ring 910; (iii) a third subset of microphones 906 mounted on the central PCB 107 a to form a third ring 914 surrounding the second ring 912; (iv) a fourth subset of microphones 906 mounted on the central PCB 107 a to form a fourth ring 916 surrounding the third ring 914; (v) a fifth subset of microphones 906 mounted on the peripheral PCB 107 b to form a fifth ring 918 surrounding the fourth ring 916; and (vi) a sixth subset of microphones 906 mounted on the peripheral PCB 107 b to form a fifth ring 919 surrounding the fourth ring 919. 107b to form a sixth ring 920 surrounding the fifth ring 918; and (vii) a seventh subset of microphones 906 mounted on the peripheral PCB 107b and near the edge of the peripheral PCB 107b to form a seventh ring 922 surrounding the sixth ring 920.

In an embodiment, the number of loops 910-922 included in the microphone array, the diameter of each loop, and/or the radial distance between adjacent loops may vary depending on the desired frequency range within which the array microphone is configured to operate and the percentage of that range to be covered by each loop. In an embodiment, the diameter of each loop in the microphone array defines the lowest frequency at which a subset of microphones within that loop can operate without picking up undesired signals (e.g., due to grating lobes). Thus, the diameter of the outermost loop 922 may determine the low end of the operating frequency range of the microphone array, and the diameters of the remaining loops may be determined by subdividing the remaining frequency range. For example, but not limitation, in some embodiments, the microphone array may be configured to cover an operating frequency range of at least 100 Hertz (Hz) to at least 10 kilohertz (KHz), with each loop covering or facilitating coverage of a different octave band or other frequency band within this range. By way of further example, in such embodiments, the outermost loop 922 may be configured to cover the lowest frequency band (e.g., 100 Hz), and the remaining loops 910 to 920 (alone or in combination with one or more other loops) may facilitate covering the remaining octave bands or frequency bands (e.g., frequency bands starting at 200 Hz, 400 Hz, 800 Hz, 1600 Hz, 3200 Hz and/or 6400 Hz).

As will be appreciated, in addition to the main lobe of the array beam, side lobes may also be present in the polar response of the microphone array. Side lobes are caused by unwanted, extraneous pickup sensitivity at angles other than the desired beam angle. Since the magnitude and frequency sensitivity of the side lobes can be changed when steering the array beam, a beam that normally has very small side lobes relative to the main lobe may have a much larger side lobe response once the beam is steered in a different direction. In some cases, the side lobe sensitivity may even rival the main lobe sensitivity at certain frequencies. However, in embodiments, including more microphones 906 within the microphone array may enhance the main lobe of a given beam and thereby reduce the ratio of side lobe sensitivity to main lobe sensitivity.

In embodiments, the loops 910-922 may be at least slightly rotated relative to a central axis 930 passing through the center of the array (e.g., the center microphone 902) to optimize the directivity of the microphone array. In such cases, the microphone array may be configured to constrain the microphone sensitivity to the main lobe, thereby maximizing the main lobe response and reducing the side lobe response. In some embodiments, the loops 910-922 may be rotationally offset from one another, such as by rotating each loop through several different angles, so that no more than two microphones 906 are axially aligned. For example, in microphone arrays with a small number of microphones, such a rotational offset may be beneficial in reducing the pickup of undesirable acoustic signals that may occur when aligning more than two microphones. In other embodiments, such as in arrays with a large number of microphones, the rotational offset (if any) may be implemented more arbitrarily, and/or other methods may be utilized to optimize the overall directivity of the microphone array.

Referring back to FIG5 , in an embodiment, each of the peripheral PCBs 107b can be designed uniformly to streamline manufacturing and assembly. For example, as shown in FIG5 , each peripheral PCB 107b can have a uniform shape, and the microphones 106b can be placed in the same position on each board 107b. In this way, any of the peripheral PCBs 107b can be coupled to any of the connectors 130 to electrically couple the peripheral PCBs 107b to the central PCB 107a. For example, in the illustrated embodiment, the microphone PCB 107 includes seven peripheral PCBs 107b, so that each of the peripheral PCBs 107b can include eight microphones in uniform positions. The remaining 64 microphones are included on the central PCB 107a, resulting in the microphone array 104 including a total of 120 microphones.

In embodiments, the total number of microphones 106 and/or the number of microphones 106b on each of the center PCB 107a and/or the peripheral PCB 107b may vary depending on, for example, the configuration of harmonic nesting, the intended operating frequency range of the array 104, the overall size of the microphone array 104, and other considerations. For example, in FIG9 , the microphone configuration 900 includes only 113 microphones, or more specifically, one center microphone surrounded by 112 microphones 906 because the ring 910 includes seven fewer microphones 906 than the corresponding ring of the microphone array 104 in FIG5 . In certain embodiments, removing these seven microphones from the first or innermost ring 910 may be achieved with little to no loss in frequency coverage or microphone sensitivity.

In an embodiment, the number of microphones 906 included in each of the loops 910-922 can be selected to produce a self-similar or repeating pattern in the microphone configuration 900. This can allow the microphone configuration 900 to be easily extended by adding one or more loops to cover more audio frequencies, or easily reduced by removing one or more loops to cover fewer frequencies. For example, in the illustrated embodiments of Figures 5 and 9, a fractal or self-similar configuration is formed by placing 7, 14, or 21 (e.g., multiples of 7) microphones 106b/906 in each of the seven loops 910-922. Other embodiments may include other repeatable arrangements of microphones 106b/906 (e.g., multiples of another integer greater than 1) or any other pattern that can simplify the manufacture of the array microphone 104. For example, but not limitation, in one embodiment, the number of microphones 906 in each of the inner rings 910 to 920 may alternate between two numbers (e.g., between 8 and 16), while the outermost ring 922 may include any number of microphones 906 (e.g., 20).

As will be appreciated, in other embodiments, the microphones 106/906 may be arranged in other configuration shapes, such as, for example, an oval, square, rectangular, triangular, pentagonal, or other polygonal shape having more or fewer subsets or loops of microphones 106/906, and/or having a different number of microphones 106/906 in each of the loops 910-922, depending on, for example, the desired distance between each loop, the overall size of the substrate 107, the total number of microphones 106 in the array 104, the predetermined audio frequency range covered by the array 104, and other performance and/or manufacturing-related considerations.

FIG10 illustrates a block diagram of an exemplary audio system 1000 including an array microphone system 1030 and a control device 1032. The array microphone system 1030 may be configured similarly to the array microphone assembly 100 shown in FIGS. 1-5 or in other configurations. For example, the array microphone system 1030 may include an array microphone 1034 similar to the array microphone 104. The array microphone system 1030 may also include an audio component 1036 that receives audio signals from the array microphone 1034 and is configured as an audio recorder, audio mixer, amplifier, and/or other component for processing the audio signals captured by the microphone array 1034. In such embodiments, the audio component 1036 may be at least partially included on a printed circuit board (not shown), such as, for example, the audio PCB 116. In other embodiments, the audio component 1036 is located in the audio system 1000 independently of the array microphone system 1030, and the array microphone system 1030 (e.g., within the control device 1032) can communicate wired or wirelessly with the audio component 1036. The array microphone system 1030 can further include an indicator 1038 similar to the indicator 126 to visually indicate the operating mode of the microphone array 1034 on the front exterior of the array microphone system 1030.

The control device 1032 can communicate with the array microphone system 1030, either wired or wirelessly, to control the audio components 1036, the microphone array 1034, and/or the indicator 1038. For example, the control device 1036 can include controls for activating or deactivating the microphone array 1034 and/or the indicator 1038. The controls on the control device 1036 can further enable adjustment of parameters of the microphone array 1034, such as directivity, gain, noise suppression, pickup pattern, muting, frequency response, and the like. In one embodiment, the control device 1036 can be a laptop computer, desktop computer, tablet computer, smartphone, proprietary device, and/or other type of electronic device. In other embodiments, the control device 1036 can include one or more switches, dimmer knobs, buttons, and the like.

In some embodiments, the microphone array system 1030 includes a wireless communication device 1040 (e.g., a radio frequency (RF) transmitter and/or receiver) for facilitating wireless communication (e.g., by receiving and/or receiving RF signals) between the system 1030 and the control device 1036 and/or other computer devices. For example, the wireless communication may be in the form of analog or digital modulated signals and may contain audio signals captured by the microphone array 1034 and/or control signals received from the control device 1036. In some embodiments, the wireless communication device 1040 may include a built-in web server for facilitating web conferencing and other similar features by communicating with remote computer devices and/or servers.

In some embodiments, array microphone system 1030 includes an external port (not shown) similar to external port 124, and system 1030 communicates with control device 1036 via a cable 1042 coupled to port 124. In one such embodiment, audio system 1000 further includes a power supply 1044 also coupled to array microphone system 1030 via cable 1042, such that cable 1042 carries power, control, and/or audio signals between the various components of audio system 1000. In a preferred embodiment, cable 1042 is an Ethernet cable (e.g., CAT5, CAT6, etc.). In other embodiments, power supply 1044 is coupled to array microphone system 1030 via a separate power cable.

As illustrated, the indicator 1038 may include a first light source 1046 and a second light source 1048. The first light source 1046 may be configured to indicate a first operating mode or state of the microphone array 1034 by turning the light on or off, and similarly, the second light source 1048 may be configured to indicate a second operating mode of the microphone array 1034. For example, the first light source 1046 may indicate whether the microphone array system 1030 has power (e.g., if the system 1030 is turned on, then whether the light 1046 is on), and the second light source 1048 may indicate whether the microphone array 1034 is muted (e.g., if the system 1030 is set to a mute setting, then whether the light 1048 is on). In other cases, at least one of the light sources 1046, 1048 may indicate whether audio is being received from an external audio source (e.g., during a web conference). In a preferred embodiment, the first light source 1046 is a first LED having a first light color, and the second light source 1048 is a second LED having a second light color different from the first light color (e.g., blue, green, red, white, etc.). The indicator 1038 can be in electronic communication with the control device 1032 and/or the audio component 1036 and controlled by the control device 1032 and/or the audio component 1036, for example, to determine which operating mode(s) can be indicated by the indicator 1038 and which color(s), LED(s), or other form of indication to assign to each operating mode.

In an embodiment, the audio component 1036 may be configured (e.g., via computer programming instructions) to enable adjustment of parameters of the microphone array 1034, such as directivity, gain, noise suppression, pickup pattern, muting, frequency response, etc. In addition, the audio component 1036 may include an audio mixer (not shown) to enable mixing of audio signals captured by the microphone array 1034 (e.g., combining, routing, changing, and/or otherwise manipulating the audio signals). The audio mixer may continuously monitor the audio signals received from each microphone in the microphone array 1034; automatically select the appropriate (e.g., optimal) lobe formed by the microphone array 1034 for a given human speaker; automatically position or steer the selected lobe directly toward the human speaker; and output an audio signal that emphasizes the selected lobe while suppressing signals from other audio sources.

In embodiments, to accommodate the possibility of several human speakers speaking simultaneously (e.g., in a boardroom setting), microphone array 1034 can be configured to simultaneously form up to eight lobes at any angle around microphone array 1034 (e.g., to simulate up to eight seated positions at a table). Due to its microphone configuration (e.g., microphone configuration 900), microphone array 1034 can form relatively narrow lobes (e.g., as shown in FIG. 11 ) to pick up fewer undesirable audio signals (e.g., noise) in the environment. The lobes can be manipulated to provide audio pickup coverage for human speakers positioned at any point within the 360-degree radius of array 1034. For example, audio component 1036 can be configured (e.g., using computer programming instructions) to allow the lobes to be manipulated or adjusted to any point in a three-dimensional space covering azimuth, elevation, and distance or radius. In embodiments, the beam pattern of microphone array 1034 can be electronically manipulated without physically moving array 1034.

Furthermore, the audio mixer can be configured to simultaneously provide up to eight individually routed outputs or channels (not shown), each output corresponding to a respective one of the eight lobes of the microphone array 1034 and generated by combining the inputs received from all microphones in the microphone array 1034. The audio mixer may also provide a ninth automix output to capture all other audio signals. As will be appreciated, the microphone array 1034 may be configured to have any number of lobes.

According to an embodiment, the lobes of the microphone array 1034 can be configured to have an adjustable beamwidth that allows the audio component 1036 to effectively track and capture audio from a human speaker as the human speaker moves within the environment. In some cases, the microphone array system 1030 and/or the control device 1032 may include a user control (not shown) that allows manual beamwidth adjustment. For example, the user control may be a knob, a slider, or other manual control that can be adjusted between three settings: normal beamwidth, wide beamwidth, and narrow beamwidth. In other cases, the beamwidth control may be configured using software running on the audio component 1036 and/or the control device 1032.

In an environment where multiple microphone array systems 1030 are included (for example) to cover a very large conference room, the audio system 1000 may include an audio mixer that receives output from the audio components 1036 included in each microphone array system 1030 and outputs a mixed output based on the received audio signals.

The audio component 1036 may also include an audio amplifier/recorder (not shown) in wired or wireless communication with the audio mixer. The audio amplifier/recorder may be a component that receives the mixed audio signal from the audio mixer and amplifies the mixed audio signal for output to speakers, headphones, live radio or TV broadcast, etc., and/or records the received signal to a medium (e.g., flash memory, hard disk, solid-state drive, tape, optical media, etc.). For example, the audio amplifier/recorder may broadcast the sound to an audience through speakers located in the environment 600 or to a remote environment via a wired or wireless connection.

10 is intended to depict the potential flow of control signals, audio signals, and/or other signals via wired and/or wireless communication links. Such signals may be in digital and/or analog format.

In an embodiment, microphone array 1034 includes multiple MEMS microphones (e.g., microphone 906) arranged in a self-similar or repeating configuration comprising concentric nested rings of microphones (e.g., rings 910-922) surrounding a central microphone (e.g., microphone 902). MEMS microphones can be very low cost and very small, which allows a large number of microphones to be placed in close proximity in a single microphone array. For example, in an embodiment, microphone array 1034 includes between 113 and 120 microphones and has a diameter of less than two feet (e.g., replacing a two-foot by two-foot ceiling tile). Furthermore, by using MEMS microphones in microphone array 1034, audio component 1036 may require less programming and other software-based configuration. More specifically, because MEMS microphones generate audio signals in a digital format, audio component 1036 does not need to include analog-to-digital conversion/modulation technology, which reduces the amount of processing required to mix the audio signals captured by the microphones. Additionally, microphone array 1034 may be inherently more capable of suppressing vibration noise due to the fact that MEMS microphones are good pressure transducers but poor mechanical transducers and have superior radio frequency immunity compared to other microphone technologies.

FIG11 is a diagram of an example microphone polar pattern 1100, under an embodiment. Polar pattern 1100 represents the directivity of a given microphone array (e.g., microphone array 1034/104 or a microphone array having microphone configuration 900), or more specifically, indicates how sensitive the microphone array is to sounds arriving at different angles about the central axis of the microphone array. Specifically, polar pattern 1100 shows the polar response of the microphone array at each of the frequencies 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz, and 8000 Hz, where the microphone array is configured to form a lobe 1102, or directional beam, at each of these frequencies and steer the lobe 1102 to an elevation angle of 60 degrees relative to the array plane. As will be appreciated, while polar pattern 1100 shows the polar response of a single lobe 1102 at a selected frequency, the microphone array is capable of simultaneously generating multiple lobes in multiple directions, each with an equivalent or at least substantially similar polar response.

As shown by polar pattern 1100, at a frequency of 1000 Hz, a side lobe 1104 is formed 10 decibels (dB) below the main lobe 1102. Furthermore, as shown in FIG11 , the low frequency response at 500 Hz has a large beamwidth indicating lower directivity, while each of the higher frequency responses at 1000 Hz, 2000 Hz, 4000 Hz, and 8000 Hz has a narrow beamwidth indicating high directivity. Thus, in an embodiment, the microphone array can provide a high overall directivity index (e.g., 19 dB) across the speech frequency range with high levels of sidelobe suppression and an optimal main-to-sidelobe ratio (e.g., 10 dB) within a specified steering angle range.

FIG12 illustrates an example method 1200 for assembling an array microphone according to an embodiment. The array microphone may be substantially similar to the array microphone 104 shown in FIG5 and/or may include a plurality of microphones arranged in a configuration substantially similar to the microphone configuration 900 shown in FIG9 . The array microphone may be arranged on a substrate, such as, for example, a printed circuit board, a carbon fiber board, or any other suitable substrate. In some embodiments, the substrate includes a central board (e.g., central PCB 107a) and a plurality of peripheral or satellite boards (e.g., peripheral PCB 107b). In such a case, method 1200 may include step 1204, in which the peripheral boards are electrically coupled to the central board, for example, using board-to-board connectors (e.g., connector 130).

In some embodiments, method 1200 includes, at step 1206, selecting a total number of microphones (e.g., microphones 106b/906) to be placed on the substrate and included in each configuration. Where the configuration includes a number of concentric rings, the number of microphones in each ring may be selected based on the desired frequency range of the array, the frequency bands assigned to the rings, the desired microphone density of the array, and other considerations, as discussed herein. In one embodiment, the total number may be selected from a group consisting of numbers that are multiples of an integer greater than 1. For example, for the rings shown in Figures 5 and 9, the integer is 7, and each ring includes 7, 14, or 21 microphones. Other patterns or arrangements may drive the selection of the total number of microphones for each configuration, as described herein.

As illustrated, method 1200 includes, at step 1208, arranging a first plurality of microphones in a first configuration on a substrate. Method 1200 also includes, at step 1210, arranging a second plurality of microphones in a second configuration on the substrate, the second configuration concentrically surrounding the first configuration. In some embodiments, method 1200 may further include, at step 1212, arranging a third plurality of microphones in a third configuration on the substrate, the third configuration concentrically surrounding the second configuration.

In an embodiment, each of the first, second, and/or third configurations includes a plurality of concentric rings positioned at different radial distances from a center point of the substrate to form a nested configuration. In some cases, the first configuration includes a different number of concentric rings than at least one of the second and third configurations. For example, in the illustrated embodiment of FIG9 , the first configuration includes at least an innermost ring 910, a second ring 912, and a third ring 914; the second configuration includes at least a fourth ring 916 and a fifth ring 918; and the third configuration includes at least a sixth ring 920 and an outermost ring 922. In each of the configurations, arranging the microphones may include, for each concentric ring, arranging a subset of microphones at predetermined intervals along the circumference of the ring. In some embodiments, the first configuration further includes a center point of the substrate, and at least one of the first plurality of microphones is positioned at the center point. Furthermore, in some embodiments, at least one of the rings included in the second configuration may be positioned on a peripheral plate. Furthermore, in some embodiments, the third configuration may be positioned entirely on the peripheral plate.

In some embodiments, method 1200 may include, at step 1214, rotating at least one of the first, second, third, and fourth configurations relative to a central axis of the array microphone (e.g., central axis 930) such that the configurations are at least slightly rotationally offset from one another to improve the overall directivity of the array microphone. Method 1200 may also include, at step 1216, electrically coupling each of the microphones to an audio processor for processing audio signals captured by the microphone.

In one embodiment, the first, second, and/or third plurality of microphones are configured to cover different predetermined frequency ranges, or in some cases, to cover octave bands within the overall operating range of the array microphone (e.g., but not limited to, 100 Hz to 10 kHz). According to one embodiment, the diameter of each concentric ring can be defined by the lowest operating frequency assigned to the microphones forming the ring. In some cases, the concentric rings included in the first, second, and/or third configurations are harmonically nested. In a preferred embodiment, the microphone array includes a plurality of MEMS microphones.

Any process description or block in the figures should be understood to represent a module, segment or portion of program code that contains one or more executable instructions for implementing specific logical functions or steps in the process, and alternative implementations are included within the scope of embodiments of the present invention in which the functions may be performed out of the order shown or discussed, including substantially simultaneously or in the reverse order (depending on the functionality involved), as will be understood by one of ordinary skill in the art.

The present invention is intended to explain how to shape and use various embodiments according to the technology rather than to limit the true, intended and reasonable scope and spirit of the invention. The above description is not intended to be exclusive or limited to the precise form disclosed. In view of the above teachings, modifications or changes are possible. The embodiments are selected and described to provide the best explanation of the principles of the described technology and its practical application, and to enable those skilled in the art to utilize the technology in the various embodiments and to envision various modifications suitable for specific purposes. All such modifications and changes are within the scope of the embodiments determined by the appended claims, and when interpreted according to the breadth to which they are reasonably, legally and fairly authorized, they may be corrected during the pendency of this patent application and all its equivalents.

Claims (31)

1. An array microphone system, comprising: Substrate; and A plurality of microphones are arranged on the substrate in several concentric nested rings of variable size, each ring comprising a subset of the plurality of microphones positioned at predetermined intervals along the circumference of the ring, wherein the rings are harmonic nested and rotated and offset relative to the central axis of the substrate. 2. The array microphone system of claim 1, wherein the loops are positioned at different harmonic-related radial distances from the center point of the central axis to form the harmonic nesting configuration. 3. The array microphone system according to claim 1, wherein the plurality of microphones are microelectromechanical systems (MEMS) microphones. 4. The array microphone system of claim 2, wherein each of the concentric nested rings forms a circle. 5. The array microphone system of claim 2, wherein the radial distance of each ring is determined based on the lowest operating frequency of the subset of microphones assigned to the ring. 6. The array microphone system according to claim 1, wherein the number of concentric nested rings is 7. 7. The array microphone system of claim 1, wherein the plurality of microphones comprises at least 113 microphones. 8. The array microphone system of claim 7, wherein the plurality of microphones comprises up to 120 microphones. 9. The array microphone system of claim 1, wherein the loop of the microphone is configured to cover a preset range of audio frequencies. 10. The array microphone system of claim 1, wherein each ring comprises a predetermined number of microphones, said predetermined number being a group of numbers selected from multiples of an integer greater than 1. 11. The array microphone system of claim 10, wherein the integer is an odd number. 12. The array microphone system of claim 1, further comprising a processor electrically coupled to the substrate and configured to receive audio signals captured by each of the plurality of microphones and to generate an output based on the received signals. 13. The array microphone system of claim 12, wherein the processor is configured to simultaneously generate multiple audio outputs based on the received audio signals. 14. The array microphone system of claim 1, further comprising an external indicator coupled to the substrate and configured to indicate an operating mode of the array microphone system. 15. The array microphone system of claim 1, wherein the substrate comprises a central printed circuit board (PCB) and a plurality of peripheral printed circuit boards (PCBs) radially positioned around the central PCB and electrically connected to the central PCB, at least one of the plurality of concentric nested rings being positioned on the plurality of peripheral PCBs. 16. The array microphone system of claim 1, further comprising at least one microphone disposed at the center point of the central axis. 17. The array microphone system of claim 1, wherein each ring is rotated off-center from the central axis by a different degree. 18. A method for assembling an array microphone, comprising: Arrange a first plurality of microphones to form a first configuration on a substrate; A second plurality of microphones are arranged to form a second configuration on the substrate, the second configuration concentrically surrounding the first configuration; Rotate at least one of the first configuration and the second configuration relative to the central axis of the array microphone; Each of the first plurality of microphones and the second plurality of microphones is electrically coupled to an audio processor, the audio processor being used to process audio signals captured by the microphones. The first configuration and the second configuration are harmonic nesting. 19. The method of claim 18, wherein the first plurality of microphones and the second plurality of microphones are configured to cover different preset frequency ranges. 20. The method of claim 18, wherein each of the first configuration and the second configuration comprises a plurality of concentric rings positioned at different harmonic-related radial distances from the center point of the substrate to form a harmonic nesting configuration. 21. The method of claim 20, wherein arranging the first plurality of microphones comprises: for each of the plurality of concentric rings, arranging a subset of the first plurality of microphones at predetermined intervals along the circumference of the ring. 22. The method of claim 20, wherein the first configuration further includes the center point of the substrate, and arranging the first plurality of microphones comprises: arranging at least one of the first plurality of microphones at the center point. 23. The method of claim 20, wherein the first configuration comprises a different number of concentric rings than the second configuration. 24. The method of claim 20, wherein the diameter of each concentric ring is defined by the lowest operating frequency of the microphone assigned to form the ring. 25. The method of claim 20, wherein the substrate comprises a central plate and a plurality of peripheral plates radially coupled to the central plate, and at least one of the concentric rings in the second configuration is contained on the plurality of peripheral plates, the method further comprising: electrically coupling the plurality of peripheral plates to the central plate. 26. The method of claim 18, further comprising: On the substrate, a third plurality of microphones are arranged in a third configuration, the third configuration concentrically surrounding the second configuration; and The third plurality of microphones are electrically coupled to the audio processor. 27. The method of claim 18, wherein the microphone is a microelectromechanical system (MEMS) microphone. 28. The method of claim 18, further comprising: selecting the total number of microphones to be included in each of the first configuration and the second configuration. 29. The method of claim 20, wherein each ring comprises a predetermined number of microphones, said predetermined number being a group of numbers selected from multiples of an integer greater than 1. 30. The method of claim 29, wherein the integer is an odd number. 31. The method of claim 20, wherein each concentric ring is rotated off-center from the central axis by a different degree.