REMOTE MICROPHONE FOR A HEARING AID

Abstract

A remote microphone device for a hearing aid system comprises a multitude of microphones providing a corresponding multitude of electric input signals; a digital signal processor for providing a processed signal in dependence of said multitude of electric input signals. The processor comprises a noise reduction system comprising at least one beamformer for providing a spatially filtered signal. The remote microphone device further comprises a wireless communication interface comprising antenna and transceiver circuitry allowing the remote microphone device to transmit said processed signal comprising said spatially filtered signal or a further processed version thereof to said hearing aid system; a rechargeable battery; a casing having a planar structure with a form and size as a standard credit card; and a user interface configured to allow the user to control functionality of the remote microphone device. The invention may e.g. be used in hearing aid systems or headsets.

Claims

1. A remote microphone device for a hearing aid system, the remote microphone device comprising a multitude of microphones, each providing an electric input signal representing sound in the environment of the microphone device, thereby providing a corresponding multitude of electric input signals; a digital signal processor for providing a processed signal in dependence of said multitude of electric input signals, the processor comprising a noise reduction system comprising At least one beamformer for providing a spatially filtered signal in dependence of said multitude of electric input signals, or signals originating therefrom; and beamformer filter coefficients, said beamformer filter coefficients being determined in dependence of a steering vector comprising as elements respective acoustic transfer functions from a target signal to each of said multitude of input transducers or acoustic transfer functions from a reference input transducer among said multitude of input transducers to each of the remaining input transducers; a wireless communication interface comprising antenna and transceiver circuitry allowing the remote microphone device to transmit said processed signal comprising said spatially filtered signal or a further processed version thereof to said hearing aid system; a rechargeable battery; wherein said remote microphone device comprises a casing having a planar structure with a form and size as a standard credit card; and comprises a user interface configured to allow a user to control functionality of the remote microphone device in dependence of one or more activation elements.

2. A remote microphone device according to claim 1 wherein said one or more activation elements comprises one or more buttons .

3. A remote microphone device according to claim 1 wherein said user interface comprises a voice control interface allowing the user to control the functionality of the remote microphone device by spoken commands.

4. A remote microphone device according to claim 1 wherein said user interface comprises one or more indicators for providing feedback to the user about a current status of the remote microphone device.

5. A remote microphone device according to claim 1 wherein at least some of said multitude of microphones are located in corners of said standard credit card form.

6. A remote microphone device according to claim 1 comprising a sensor allowing to detect an orientation of the remote microphone device.

7. A remote microphone device according to claim 6 configured to enter an omnidirectional mode of operation in case its planar orientation is perpendicular to the force of gravity of the earth.

8. A remote microphone device according to claim 1 configured to determine which of the two planar outer surfaces (x,y) of the casing of the device is presently facing upwards when the device is resting on a planar, horizontal, carrier.

9. A remote microphone device according to claim 1 configured to exchange information with a further remote device.

10. A remote microphone device according to claim 1 wherein each of the multitude of microphones is mounted in a suspension comprising a flexible material in a cavity or opening in the credit card size casing of the remote microphone device.

11. A remote microphone device according to claim 1 wherein microphone inlets of said multitude of microphones are covered with a filter or membrane.

12. A remote microphone device according to claim 11 comprising a membrane for providing an acoustically transparent closure.

13. A remote microphone device according to claim 11 wherein the membrane is placed in the casing on a substrate where the microphones are located.

14. A remote microphone device according to claim 13 wherein the microphones are mounted on the substrate to have a microphone inlet opening facing a first surface of the substrate, and wherein the substrate comprises an opening concentrical with the microphone inlet opening, and wherein membrane is placed on the opposite, second surface of the substrate covering said opening in the substrate.

15. A remote microphone device according to claim 1 comprising a charging coil configured to wirelessly receive charging energy from an external charging device allowing said charging coil to charge said rechargeable battery.

16. A remote microphone device according to claim 15 wherein the charging coil is located on the battery, separated from a battery housing by an electromagnetically shielding layer.

17. A remote microphone device according to claim 1 wherein said casing has a dimension of less than or equal to 2 mm in a direction perpendicular to its planar surfaces.

18. A hearing aid system comprising at least one hearing aid and a remote microphone device according to claim 1.

19. A hearing aid system according to claim 18 adapted to establish a communication link between the remote microphone device and an auxiliary device to provide that data can be exchanged or forwarded from one to the other.

20. A hearing aid system according to claims 19 comprising a user interface — implemented in the auxiliary device — for controlling the hearing aid system.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0090] The aspects of the disclosure may be best understood from the following detailed description taken in conjunction with the accompanying figures. The figures are schematic and simplified for clarity, and they just show details to improve the understanding of the claims, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts. The individual features of each aspect may each be combined with any or all features of the other aspects. These and other aspects, features and/or technical effect will be apparent from and elucidated with reference to the illustrations described hereinafter in which:

[0091] FIG. 1 schematically shows an outer appearance of a credit card size remote microphone device according to an embodiment of the present disclosure,

[0092] FIG. 2 schematically shows a block diagram of a credit card size remote microphone device according to an embodiment of the present disclosure,

[0093] FIG. 3A shows an exemplary microphone suspension design of a emote microphone device according to the present disclosure; and

[0094] FIG. 3B shows a microphone suspension design (e) with openings (g) to allow for sound to enter from both sides of the card (left part), and a microphone and inlet covered with filter or membrane (c) on both sides of the card (right part),

[0095] FIG. 4 shows four examples of different possible microphone positions for creating a microphone array in a remote microphone device according to the present disclosure,

[0096] FIG. 5A shows a binaural hearing aid system comprising a remote microphone device according to the present disclosure; and

[0097] FIG. 5B shows a hearing aid system comprising a remote microphone device in communication with an auxiliary device according to the present disclosure,

[0098] FIG. 6 shows two different beamformer scenarios of a remote microphone device according to the present disclosure,

[0099] FIG. 7A shows a first exemplary arrangement of components and battery in a remote microphone device according to the present disclosure, and

[0100] FIG. 7B shows a second exemplary arrangement of components and battery in a remote microphone device according to the present disclosure, and

[0101] FIG. 8 schematically shows a in a vertical cross-sectional view (‘z-direction’ perpendicular to the planar surfaces) of a part of the remote microphone device according to the present disclosure comprising details of a MEMS microphone inlet.

[0102] The figures are schematic and simplified for clarity, and they just show details which are essential to the understanding of the disclosure, while other details are left out. Throughout, the same reference signs are used for identical or corresponding parts.

[0103] Further scope of applicability of the present disclosure will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only. Other embodiments may become apparent to those skilled in the art from the following detailed description.

DETAILED DESCRIPTION OF EMBODIMENTS

[0104] The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. Several aspects of the apparatus and methods are described by various blocks, functional units, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). Depending upon particular application, design constraints or other reasons, these elements may be implemented using electronic hardware, computer program, or any combination thereof.

[0105] The electronic hardware may include micro-electronic-mechanical systems (MEMS), integrated circuits (e.g. application specific), microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), gated logic, discrete hardware circuits, printed circuit boards (PCB) (e.g. flexible PCBs), and other suitable hardware configured to perform the various functionality described throughout this disclosure, e.g. sensors, e.g. for sensing and/or registering physical properties of the environment, the device, the user, etc. Computer program shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise.

[0106] The present application relates to the field of hearing aids. The disclosure relates e.g. to a remote microphone configured to communicate with a hearing aid.

[0107] FIG. 1 shows an outer appearance of a credit card size remote microphone device (RMC) according to an embodiment of the present disclosure.

[0108] The present disclosure proposes a small wireless remote microphone array in the (planar) size equal to or similar to (e.g. within +/- 5%, or less) a standard credit card (ISO/IEC 7810 Size ID-1; 85.6 x 53.98 mm). It may e.g. have a larger thickness, twice the thickness of a standard credit card (e.g. 1.0 -2.0 mmm). The microphone device may be referred to as a Remote Mic Card (RMC). The RMC may include one or more (such as a majority or all) of the following features: [0109] At least on, preferably, two or more microphones for picking up sound. [0110] A signal processor enabling noise reduction and/or beamforming on the picked-up sound signal(s). Signal processing may include Voice Activity Detection, e.g. so that a signal is only transmitted from the RMC, if voice activity is present in the captured signal(s). [0111] A wireless transmitter that can transmit the cleaned up (spatially filtered and/or noise reduced) signal to the user’s hearing aid(s). The wireless transmission may e.g. include Classic Bluetooth, Bluetooth Low-Energy (BLE), e.g. Bluetooth LE Audio, Ultra-Wide-Band (UWB) or a proprietary wireless connection designed for low power and low latency to the hearing aids. UWB resides in a different frequency range (3-11 GHz) than Bluetooth (2.4-2.5 GHz)) and has a low latency. Although commercially enabled, no standard for audio transmission has yet been agreed on for UWB. [0112] A wireless charging coil. The wireless charging may e.g. be Qi-charger (or other (e.g. resonant) charging technology) compatible to enable charging on standard wireless chargers. [0113] As an alternative to wireless charging, wired connection to charging pads/terminals may also be a solution. The charging pad interface may e.g. be provided according to the general ISO/IEC 7816 standard for electronic identification cards and payment card. The terminals may alternatively be arranged in any other locations on the card. - One or more buttons (e.g. capacitive touch, capacitive finger swipe, dome switch), used for turning on device and/or select a directional mode of a beamformer and optionally for remotely controlling the hearing aid(s). [0114] One or more LEDs for visual feedback to the user as indication of on/off status and/or settings for beamformer mode (omni or directional mode). [0115] An accelerometer to automatically detect whether the card is lying flat on a table, held in a hand, or being worn in upright position by a user (or communication partner). [0116] A buzzer (or loudspeaker) for acoustical feedback to the user (may e.g. be used to find a lost card (RMC)).

[0117] An advantage of the format of the RMS is that its planar dimension (e.g. of a credit card) facilitates beamforming (allowing a relatively large distance between microphones (e.g. in a two-dimensional plane), thereby improving low-frequency performance (e.g. narrower beams) of the beamformer).

[0118] Another advantage of the form factor is easier storage, e.g. in a wallet, in a smartphone cover, in a pocket and/or bag.

[0119] FIG. 2 shows a block diagram of a credit card size remote microphone device (RMC) according to an embodiment of the present disclosure.

[0120] A remote microphone device (RMC) according to the present disclosure may be produced using one or more of the following technical features [0121] Laminating card technology into standard credit card size 85.6 x 54.0 mm, but e.g. with a larger thickness, e.g. 1.5 mm (where the standard credit card thickness is 0.75 mm), as indicated in FIG. 2. [0122] MEMS microphones (e.g. four, e.g. one in each ‘corner’, cf. ‘mic’ in FIG. 2) having a thickness of approximately 1 mm. [0123] Vibration attenuation (decoupling) of microphones (possibly based on suspension and/or signal processing), cf. FIGS. 3A, 3B. [0124] Dust protection of microphone inlet(s), cf. ‘3’ in FIG. 3B. [0125] A battery (e.g. rechargeable, e.g. Li-Ion) having a thickness of approximately 0.4 mm, cf. ‘Battery (49x49x0.4 mm)’ in FIG. 2. [0126] A wireless charging coil, e.g. allowing resonant charging from standard chargers (e.g. based on resonant charging, e.g. for mobile telephones, cf. ‘Wireless charging coil’ in FIG. 2). [0127] Battery/charge management algorithm for managing the charging (and possibly de-charging) of the rechargeable battery (cf. e.g. ‘BM’ in FIG. 2 connected between the charging coil and the battery via connecting elements (CON) and appropriate wiring (cf. dashed lines), e.g. on a substrate (e.g. a PCB)). [0128] Digital audio signal processing, e.g. including beamforming, as known from hearing aids (cf. ‘DSP’ in FIG. 2). [0129] Antenna and transceiver circuitry (cf. ANT, RF) for establishing a wireless link to a hearing aid (or a hearing aid system) and/or to an auxiliary device (e.g. a smartphone or remote control device), e.g. via Bluetooth (e.g. Bluetooth Low Energy, such as Bluetooth LE Audio) or UBW. [0130] An indicator, e.g. a visual indicator, such as an LED, for providing status information to the user.

[0131] A remote microphone device (RMC) according to the present disclosure may provide one or more of the following advantages: [0132] Easy storage for the user. Can be stored in wallet or smartphone cover made for credit card storage. [0133] Large microphone distance (up to 95 mm, e.g. between ‘diagonal’ microphones (mic) in FIG. 2), despite being small in volume (6.9 cm.sup.3), for better beamforming in lower frequencies. (Current solutions have other form factors, may e.g. have a volume of 25 cm.sup.3 and a maximum of 13 mm microphone distance). [0134] Discreet to use both when held in a hand (cf. FIG. 1), worn in a shirt pocket as a partner microphone or placed on a table as a table microphone. [0135] Easy to use with simple user interface. Turn on/off (cf. ‘Button’ in FIG. 2). [0136] Easy to charge by using standard wireless chargers (e.g. Qi). [0137] Easy to carry. [0138] Durable and flexible to use. Card including lithium-Ion battery (or Lithium Polymer) allow being bent, cf. ‘Battery (49x49x0.4 mm)’ in FIG. 2. [0139] Long battery use time. [0140] Bluetooth Low-Energy (BLE) beacon tracking feature for easy localization of lost mic card.

An Example

[0141] A remote microphone device (RMC) according to the present disclosure may for example be implemented using: [0142] 4 x MEMS P8AC03 Sonion microphones. [0143] Dust/moist fitters for microphones. [0144] Battery Grepow GRP0449049 49.0 x 49.0 x 0.4 mm with 48 mAh @ 3.7 V Capacity. [0145] Wireless charge coil printed in a flex PCB. [0146] Radio Frequency (RF) chip for wireless communication (e.g. UWB). [0147] Wireless RF antennae. [0148] Dome Switch for turning on/off the device. [0149] DSP (audio) chip with 4 microphone input channels.

[0150] FIG. 3A shows an exemplary side view microphone suspension design of a remote microphone device according to the present disclosure. The microphone (a) (mic in FIG. 2) is mounted in a rubber suspension (e) (or other suitably flexible material), with sound inlet (b), mounted in a cavity or opening (c) in the credit card size casing (f) of the remote microphone device (RMC in FIG. 2). The suspension (e) is designed so that the microphone and suspension do not touch the support (e.g. a table) that the card is placed on (during use of the remote microphone device), to avoid transmission of vibrations from the support to the microphone (a).

[0151] The left part of FIG. 3B shows an exemplary top view of the microphone suspension design (e) of FIG. 3A with openings (g) to allow for sound to enter from both sides of the card. A circular opening with four cone shaped support ribs between the microphone unit and the wall of the circular opening in the planar structure of the credit card form remote microphone device. The right part of FIG. 3B illustrates a microphone (mic in FIG. 2) and its inlet covered with a filter (e.g. a dust-filter) or membrane (c) on both sides of the credit card form remote microphone device.

[0152] FIG. 4 shows four examples (A, B, C, D) of different possible microphone (mic) positions for creating a microphone array in a remote microphone device (RMC) according to the present disclosure. The four examples a remote microphone device (RMC) comprise three (A, B, C) or four microphones (D), respectively. Other numbers may be used (e.g. 2 or 5 or more microphones).

[0153] Microphone configuration A has a large microphone distance and may be good at creating a beamformer in many directions. Configuration B has the microphones located in one end of the card, so when the card is held in the hand there is less risk of blocking a microphone inlet with the fingers. Configuration C has the microphone arranged in a line making a good beamformer sensitivity in the axis of the microphone positions, and at variating microphone distances to ensure good performance in a broad frequency range. Configuration D has 4 microphones facilitating a more narrow beamformer performance than 3 microphones. The number of microphones may be increased for even better beamforming performance.

[0154] FIG. 5A shows a binaural hearing aid system comprising a remote microphone device according to the present disclosure.

[0155] The remote microphone device (RMC) comprises (antenna and) transceiver circuitry (RF) for establishing a communication link (WL) to the hearing aid(s). The remote microphone device (RMC) may e.g. comprise one or more sensors for classifying the environment around the it, in addition to the microphones, e.g. for of estimating background noise, or vibrations in the emote microphone device. The communication link (WL) may have a limited range of operation. In other words, the distance (D) between the hearing aids (HA1, HA2) and the emote microphone device must be below a critical distance (D.sub.max, depending on the transmit power and the technology used for establishing the link) to establish or maintain the the communication link (WL). The communication link (WL) may e.g. be based on Bluetooth (e.g. Bluetooth Low Energy, such as Bluetooth LE Audio) or UWB.

[0156] FIG. 5B shows a hearing aid system comprising a remote microphone device in communication with an auxiliary device according to the present disclosure. FIG. 5B shows an embodiment of a hearing aid (HD) comprising a BTE-part (BTE) located behind an ear or a user and an ITE part (ITE) located in an ear canal of the user, and an auxiliary device (AD), and a remote microphone device (RMC) according to the present disclosure in communication with each other (via wireless communication links WL21, WL22, WL3, respectively). The auxiliary device comprising a user interface (UI) for controlling the hearing aid and optionally the remote microphone unit (RMC). Together, the hearing aid (HA) and the auxiliary device (AD) may constitute a hearing system according to the present disclosure.

[0157] FIG. 5B (and 5A) illustrates an exemplary hearing aid (HD) formed as a receiver in the ear (RITE) type hearing aid comprising a BTE-part (BTE) adapted for being located behind pinna and a part (ITE) comprising an output transducer (SPK, e.g. a loudspeaker/receiver) adapted for being located in an ear canal (Ear canal) of the user. The BTE-part (BTE) and the ITE-part (ITE) are connected (e.g. electrically connected, e.g. via a cable comprising a multitude of conductors, e.g. three or more, such as six or more) by a connecting element (IC). In the embodiment of a hearing aid of FIGS. 5B (and 5A), the BTE part (BTE) comprises two input transducers (here microphones) (M.sub.BTE1, M.sub.BTE2) each for providing an electric input audio signal representative of an input sound signal from the environment (in the scenario of FIG. 5B, from sound source S, e.g. a communication partner). The hearing aid (HD) of FIGS. 5B (and 5A) further comprises two wireless transceivers (WLR.sub.1, WLR.sub.2) for receiving and/or transmitting signals (e.g. comprising audio and/or information, e.g. audio data and/or control signals according to the present disclosure). The hearing aid (HD) further comprises a substrate (SUB) whereon a number of electronic components are mounted, functionally partitioned according to the application in question (analogue, digital, passive components, etc.), but including a configurable digital signal processor (DSP), a front-end chip (FE), and a memory unit (MEM) coupled to each other and to input and output units via electrical conductors Wx. The mentioned functional units (as well as other components) may be partitioned in circuits and components according to the application in question (e.g. with a view to size, power consumption, analogue vs digital processing, etc.), e.g. integrated in one or more integrated circuits, or as a combination of one or more integrated circuits and one or more separate electronic components (e.g. inductor, capacitor, etc.). The configurable signal processor (DSP) provides an enhanced audio signal (e.g. intended to compensate for a hearing impairment of the user), which is presented to the user. The front-end integrated circuit (FE) is adapted for providing an interface between the configurable signal processor (DSP) and the input and output transducers, etc., and typically comprising interfaces between analogue and digital signals. The input and output transducers may be individual separate components, or integrated (e.g. MEMS-based) with other electronic circuitry. In the embodiment of a hearing aid in FIG. 5B, the ITE part (ITE) comprises an output unit in the form of a loudspeaker (receiver) (SPK) for converting the electric signal (OUT) to an acoustic signal (providing, or contributing to, acoustic signal S.sub.ED at the ear drum (Ear drum). The ITE-part further comprises an input unit comprising an input transducer (e.g. a microphone) (M.sub.ITE) for providing an electric input audio signal representative of an input sound signal S.sub.ITE from the environment at or in the ear canal. In another embodiment, the hearing aid may comprise only the BTE-microphones (M.sub.BTE1, M.sub.BTE2). In yet another embodiment, the hearing aid may comprise an input unit located elsewhere than at the ear canal (e.g. facing the eardrum) in combination with one or more input units located in the BTE-part and/or the ITE-part. The ITE-part further comprises a guiding element, e.g. a dome, (DO) for guiding and positioning the ITE-part in the ear canal of the user.

[0158] The hearing aid (HD) exemplified in FIGS. 5B (and 5A) is a portable device and further comprises a battery (BAT) for energizing electronic components of the BTE- and ITE-parts.

[0159] The hearing aid (HD) may comprise a directional microphone system (e.g. a beamformer filter) adapted to enhance a target acoustic source among a multitude of acoustic sources in the local environment of the user wearing the hearing aid.

[0160] The hearing aid of FIGS. 5B (and 5A) may constitute or form part of a binaural hearing aid system according to the present disclosure.

[0161] The hearing aid (HD) according to the present disclosure may comprise a user interface (UI), e.g. as shown in the bottom part of FIG. 5B implemented in an auxiliary device (AD), e.g. a remote control, e.g. implemented as an APP in a smartphone or other portable (or stationary) electronic device (e.g. a charging station). The hearing aid system may be configured to allow the user to control functionality of the hearing aid system, e.g. the hearing aid (HD) via the user interface (UI) (e.g. via communication link WL21). It may, however, also be configured to allow the user to control functionality of the remote microphone (RMC) via the user interface (UI) (e.g. via communication link WL3). In the embodiment of FIG. 5B, the screen of the user interface (UI) illustrates a Remote Mic APP. The user may configure the remote microphone device (RMC) via the APP. The user may e.g. switch the remote microphone device on or off (as indicated by the filled square symbol ■ next to “On/off” indication on the screen). The user may e.g. further select activation of beamforming (as indicated by the filled square symbol ■ next to ‘DIR (select D1, D2, D3)’ indication on the screen under the hearing ‘Directional system’). The user may when directional system is activated select directions relative to the credit card form of the remote microphone device in which (e.g. fixed) beamformers should be directed. In the example of FIG. 5B, directions D1 and D2 have been selected (as indicated by the filled square symbol - next to ‘D1’ and ‘D2’ (and bold arrows D1, D2)). Unselected options are indicated by open square symbols (■) (cf. e.g. direction D3 and the option ‘Omni’ instead of ‘DIR’). The Remote Mic APP May e.g. be offered as an alternative (or in additional) to activation elements located on the remote microphone device (RMC).

[0162] The communication links WL21, WL22, WL3 may e.g. be based on far field communication, e.g. Bluetooth or Bluetooth Low Energy, e.g. Bluetooth LE Audio (or similar technology, e.g. UWB), implemented by appropriate antenna and transceiver circuitry in the hearing aid (HD) in the auxiliary device (AD), and in the remote microphone device (RMC), as indicated by transceiver unit (WLR.sub.2) in the hearing aid, and (ANT, RF) in the remote microphone device (RMC).

[0163] The hearing system may be configured to allow the audio data picked up by the remote microphone device (RMC) to be transmitted to the hearing aid (HD) via a communication link (WL22) (and/or to the auxiliary device (AD) via a communication link (WL3).

[0164] FIG. 6 shows two different beamformer scenarios of a remote microphone device (RMC) comprising a multitude of microphones according to the present disclosure, the top part, denoted ‘Fixed beamformer’, illustrating (relative) enhancement of sounds (e.g. a speaker) in one (fixed) direction, and the bottom part, denoted ‘Adaptive beamformer’, illustrating (relative) enhancement of sounds (e.g. a speaker) in any direction (relative to the orientation of the remote microphone device (RMC)).

[0165] The top part (denoted ‘Fixed beamformer’) of FIG. 6 illustrates three different beamformers, all having a fixed target direction (e.g. in a direction as indicated by the microphone symbol on the remote microphone device (RMC)) for which the directional system has maximum sensitivity and fixed or adaptive attenuation of sound from other directions than the target direction. Such beamformers may e.g. be implemented in dependence of a multitude of electric input signals from a microphone array of the remote microphone device (RMC) and fixed beamformer filter coefficients or adaptively updated filter coefficients that are updated when no speech is present in the microphone signals (as e.g. indicated by a voice activity detector), to thereby adapt to a changing noise field (while keeping the target direction fixed).

[0166] The bottom part (denoted ‘Adaptive beamformer’) of FIG. 6 illustrates three different beamformers, having an adaptive target direction (here a direction towards a (target) speaker (TLK)) for which the directional system has maximum sensitivity and adaptive attenuation of sound from other directions than the target direction. Such beamformers may be implemented in dependence of a multitude of electric input signals from the microphone array of the remote microphone device (RMC) and adaptively updated filter coefficients. The beamformer filter coefficients may e.g. be updated, respectively, when speech is present (to update a target direction/location, e.g. update a steering vector) and when no speech is present (to update the noise field, e.g. varying or (relatively) moving noise sources, cf. noise source (NS) in FIG. 6, e.g. update a noise covariance) in the microphone signals (as e.g. indicated by a voice activity detector). Various aspects of beamforming is e.g. discussed in [Brandstein &Ward; 2001].

[0167] FIG. 7A shows a first exemplary arrangement of components (E-CMP, mic, BUT, LED) and battery (BAT) in a remote microphone device (RMC) according to the present disclosure. In the embodiment of FIG. 7A, the components, comprising electronic components (E-CMP), (two) microphones, a button (BUT) and a light emitting diode (LED) are assembled on a common substrate, here a printed circuit board (PCB). The PCB comprising the components extend over a first part of the casing (having outer surfaces that constitutes the outer limits of the remote microphone device). In the embodiment of FIG. 7A the battery (BAT) extends over a second part of casing. The PCB and the battery (first and second parts) of the embodiment of FIG. 7A are non-overlapping (to keep the thickness of the casing at a minimum. The charging coil (C-COIL) for wirelessly charging the battery is located on the battery housing (but electrically isolated therefrom) and electrically connected to terminals of the battery. An electro-magnetic shield (e.g. a ferrite layer) is preferably located between the coil and the battery housing to avoid heating of the battery housing during wireless charging. The battery is connected to the PCB and components thereon to provide the necessary power to operate the remote microphone device (RMC). In the embodiment of FIG. 7A, two microphones (mic) are located along one of the sides (here ethe longest side) of the casing of the device. In other words, the microphone axis of the two microphones is parallel to the longest side of the casing. Thereby, a beamformer of the remote microphone device (RMC) may be arranged to provide its maximum sensitivity in a direction parallel to the longest side of the casing. In other words, the remote microphone device (RMC) may be easily oriented to pick up sound from a known direction (e.g. the users voice by arranging the device (e.g. in a shirt pocket) so that it ‘points’ in a direction of the user’s mouth).

[0168] The dimensions of the credit card size remote microphone device (RMC) are in the planar (x, y) directions approximately x=53.98 mm +/- 5%, y = 85.6 mm +/- 5% and perpendicular (z) to the to the planar directions having a thickness of less than or equal to 2 mm. The housing may preferably be constituted by a plastic material (e.g. of the same kind used for credit cards or bank cards comprising electronic components). The components and battery of the remote microphone device (RMC) may thus be embedded in the plastic material. During production, care should be taken to avoid or minimize the flow of that filler (plastic) material into cavities around microphone inlets and button (e.g. a dome switch). This may e.g. be achieved by covering the microphone inlets with a protecting layer allowing sound to reach the microphone membrane while allowing a hermetically sealed (and thus water resistant, or water proof, casing to be provided (e.g. according to IP67, or IP68, or IP69). Hermetic sealing has the advantage of minimizing the damage of electronic components of the remote microphone device (RMC) due to penetration of water or other electrically conducting or corroding liquids, and/or due to dust or other materials occluding the microphone inlets, etc. In addition to a sealing layer, the microphone inlets may additionally be provided with a mechanical (e.g. web-like) filter as the outermost protection against occlusion. Additionally, the outer surfaces (and/or the filters protecting the microphone inlets) may be fully or partially coated with a hydrophobic coating to minimize adherence of liquids to the surfaces of the casing (or filters). The microphone inlets may be provided only from one of the planar surfaces of the casing of the remote microphone device (RMC), e.g. the opposite side from which the activation element (e.g. a dome switch button) is accessible. Thereby the microphones (e.g. MEMS microphones) may be appropriately mounted on the PCB, so that the microphone inlet is accessible via an opening in the PCB.

[0169] FIG. 7B shows a second exemplary arrangement of components and battery in a remote microphone device according to the present disclosure comprising the same components as the embodiment of FIG. 7A. In the embodiment of FIG. 7B, however, the PCB extends below or above the battery to allow the charging coil to be located there on, and if the PCB extends beneath the battery creates room for additional microphones at the bottom end of the card (cf. two microphones (mic) located in the lower corners of the device (lower being defined relative to the orientation of the card shown in FIGS. 7A, 7B). The embodiment of FIG. 7B this comprises four microphones, each being located in a corner of the device. Thereby a flexible (e.g. adaptive) beamformer may be provided that it able to have its maximum and minimum sensitivities in all directions of a plane extending the plane defined by the credit card form casing of the device. The two lower microphones are arranged on the same side of the PCB as the other components described in connection with FIG. 7A (to keep the thickness of the casing at a minimum). Again, a layer of an electromagnetically shielding material may preferably be added between the charging coil (C-COIL) and the battery (BAT).

[0170] An advantage of the remote microphone device (RMC) as described is that is does not comprise any electric connectors. All communication to and from the card may be wireless. Likewise, charging of the rechargeable battery and programming or firmware updates may all be provided wirelessly.

[0171] FIG. 8 schematically shows a in a vertical cross-sectional view (‘z-direction’ perpendicular to the planar surfaces) of a part of the remote microphone device according to the present disclosure comprising details of a MEMS microphone inlet. FIG. 8 shows a cross-section where the two planar outer surfaces of the casing are indicated. The mutual distance between the two planar surfaces represents the ‘thickness’ (in a z-direction perpendicular to the planar surfaces) of the remote microphone device. The thickness may e.g. be limited to a predefined tolerated thickness, e.g. to be smaller than or equal to 3 mm, such as smaller than or equal to 2 mm. The MEMS microphone (MEMS mic) is shown to be soldered to a printed circuit board (PCB) via solder dots (cf. black elliptic structures denoted ‘solder’). An opening (e.g. circular) is arranged in the PCB (e.g. larger than the microphone inlet of the MEMS microphone itself), and a further opening is arranged in the casing to allow sound to reach a membrane of the MEMS microphone through the thereby created microphone inlet. A sealing membrane (Membrane) is shown to cover the opening in the PCB and to provide a certain amount of water resistance while being predominantly acoustically transparent. The membrane is shown to be located in the opposite side of the PCB compared to the mounting of the MEMS microphone. Thereby it is protected from the direct heat used when soldering the component to the PCB and protects the inlet of the MEMS microphone during the ‘enclosure process where the casing is applied to the PCB, battery and components of the remote microphone device (which may also involve flow of plastic material). A further protection of the microphone inlet is indicated in the form of a mesh-filter (Filter) for limiting the entrance of dust and other particles. The plastic casing (‘casing’) is (schematically) shown to have outer as well as inner parallel surfaces. In practice the inner surfaces may be adapted to the enclosed structures (e.g. during assembly (e.g. involving heating) of the casing to enclose the components and battery of the device).

[0172] Embodiments of the disclosure may e.g. be useful in applications such as hearing aids or headsets.

[0173] It is intended that the structural features of the devices described above, either in the detailed description and/or in the claims, may be combined with steps of the method, when appropriately substituted by a corresponding process.

[0174] As used, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well (i.e. to have the meaning “at least one”), unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, but an intervening element may also be present, unless expressly stated otherwise. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. The steps of any disclosed method are not limited to the exact order stated herein, unless expressly stated otherwise.

[0175] It should be appreciated that reference throughout this specification to “one embodiment” or “an embodiment” or “an aspect” or features included as “may” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the disclosure. The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects.

[0176] The claims are not intended to be limited to the aspects shown herein but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more.

REFERENCES

[0177] WO1994020951A1 (Walters & Agarwal) 15.Sep.1994 [0178] US7006846B2 12.Sep.2002 (Northrup Grumman Corporation) [0179] [Brandstein &Ward; 2001] M. Brandstein and D. Ward, Eds., “Microphone Arrays: Signal Processing, Techniques and Applications”, Springer 2001.