Hearing instrument

An audio system includes a headset and a portable computing device. The headset includes a first speaker and a first microphone, a second speaker, a second microphone and a processing unit. The first microphone and the second microphone output a first signal and a second signal, respectively. The processing unit combines the first electrical signal and the second electrical signal into a third electrical signal, and communicates the third electrical signal to a portable computing device through an output channel. The portable computing device preferably includes an application that separates the third electrical signal into the first electrical signal and the second electrical signal. The application compensates the first electrical signal and the second electrical signal for a hearing loss of an individual.

BACKGROUND

1. Technical Field

This invention generally relates to hearing instruments. More particularly, the invention relates to an audio system implemented as a hearing instrument.

2. Related Art

An individual having difficulties in hearing or having partial hearing impairment may use a hearing aid to listen. The hearing aid is an electroacoustic device that may be designed to fit in the individual's ear. The hearing aid amplifies sound sufficiently for the individual to hear the sound. The individual may be interested in using portable electronic devices having audio output such as a mobile communication device, a music player, and the like, with the hearing aid. The individual may electrically connect the portable electronic device with the hearing aid or may use portable electronic device directly. In both instances, the individual has to use both the hearing aid and the portable electronic device. US2011317858 describes a hearing aid frontend device for frontend processing of ambient sounds and adapted for being worn by a user. The hearing aid comprises first and second sound collectors adapted for collecting ambient sound with spatial diversity. The sounds collected by the sound collectors are processed by a sound processor. The sound process comprises a digital signal processor for beamforming sounds collected by the first and second collectors, and the processed sounds are subsequently subject to adaptive noise cancellation.

SUMMARY

Disclosed is an audio system. The audio system includes a headset and a portable computing device. The headset includes a first output transducer, e.g. a speaker, a first microphone, a second output transducer, e.g. a speaker, a second microphone and a processing unit. The first microphone outputs a first electrical signal. The second microphone outputs a second electrical signal. The processing unit receives the first electrical signal, and the second electrical signal. The processing unit combines the first electrical signal and the second electrical signal into a third electrical signal. Further, the processing unit communicates the third electrical signal to a portable computing device through an output channel. Alternatively, the processing unit may be configured to communicate the first and second electrical signals via individual (e.g. third and fourth, or first and second output) channels. The portable computing device separates the third electrical signal into the first electrical signal and the second electrical signal, e.g. by means of an application (sometimes denoted an ‘APP’), i.e. a software program executing on the portable computing device (or receives the first and second electrical signals directly). The portable computing device and/or the application processes the first electrical signal and the second electrical signal to compensate for a hearing loss of an individual of the audio system. The portable computing device and/or the application communicates the processed first electrical signal to the first output transducer, e.g. a speaker, through a first channel, and the processed second electrical signal to the second output transducer, e.g. a speaker, through a second channel. In the following, the term ‘speaker’ is used for the output transducer. In an embodiment ‘the speaker’ is a conventional (miniature) loudspeaker for converting an electric signal to an acoustic sound, such conversion comprising the generation of vibrations of air in a human audible frequency range (e.g. within the range from 20 Hz to 20 kHz). In an embodiment, the (output transducer) speaker is a vibrator for converting an electric signal to a vibration of a bone (e.g. the skull or a jaw) of a person, such vibrator e.g. forming part of a bone anchored hearing aid. In an embodiment, one or more of the (communication) channels is/are established via wireless link(s). In an embodiment, one or more of the (communication) channels is/are established via wired link(s). The links may be implemented according to standardized or proprietary schemes. In an embodiment, a wireless link may be implemented as an inductive link based on utilizing near-field properties of the electromagnetic field. In an embodiment, a wireless link may be implemented based on far-field properties of the electromagnetic field (radiated fields, RF) and e.g. complying with a communication standard. In an embodiment, the communication standard is classic Bluetooth as specified by the Bluetooth Special Interest Group (SIG). In an embodiment, the communication standard is another standard or proprietary protocol (e.g. a modified version of Bluetooth, e.g. Bluetooth Low Energy modified to comprise an audio layer).

The audio system helps the individual to use the portable computing device as a hearing aid in addition to general functions of the portable computing device. Further, the portable computing device can be used as or form part of a binaural hearing aid (e.g. in cooperation with the headset). It is an advantage that the individual does not have to use a separate hearing aid in conjunction with the portable computing devices.

In one embodiment, the headset is configured to be communicatively coupled to the portable computing device through a connector. In an embodiment, the connector includes a first speaker contact, a second speaker contact and a microphone contact. In an embodiment, the first speaker contact is coupled to the first speaker through the first channel. In an embodiment, the second speaker contact is coupled to the second speaker through the second channel. In an embodiment, the microphone contact is coupled to the processing unit through the third channel. It is an advantage that currently available portable computing devices with connectors having only one contact for microphone signals can be used together with the headset as a binaural hearing aid. In an embodiment, the connector comprises two (or more) microphone contacts. In an embodiment, the two (or more) microphone contacts are coupled to the processing unit through third and fourth (separate) channels. In an embodiment, the connector is configured to electrically connect the headset to the portable computing device via a wired connection, e.g. comprising a cable comprising a number of independent electrical conductors (insulated from each other), and corresponding connectors. In an embodiment, the cable comprises separate cables (or a split cable) for connecting the first and second earpieces of the headset with the processing unit and/or the portable computing device.

The portable computing device may be a mobile communication device, a portable music player, a personal digital assistant (PDA), or a laptop. Examples of mobile communication device include, without limitation, programmable mobile phones and cell phones, particularly smartphones on which applications, known as “APPs”, may be installed and executed.

In one embodiment, the processing unit applies a low pass filter with a first cut-off frequency to the first electrical signal and the second electrical signal. The processing unit transposes the filtered first electrical signal by a first frequency shift to move the filtered first electric signal to frequencies above the first cut-off frequency. The first frequency shift should thus be equal to or larger than the first cut-off frequency. Further, the processing unit adds the (filtered and) transposed first electrical signal and the filtered second electrical signal to generate the third electrical signal.

In one embodiment, the portable computing device and/or the application separates the third electrical signal by applying a low pass filter with a cut-off frequency equal to the first cut-off frequency to the third electrical signal to obtain the second electrical signal. The portable computing device and/or the application applies a high pass filter with a cut-off frequency somewhere in the range between the first cut-off frequency and the first frequency shift to the third electrical signal. The portable computing device and/or the application transposes the high-passed filtered signal back to the original frequencies below the first cut-off frequency to obtain the first electrical signal.

In another embodiment, the processing unit applies a low pass filter with a first cut-off frequency to the first electrical signal and the second electrical signal. The processing unit generates a difference signal by subtracting the filtered second electrical signal from the filtered first electrical signal. The processing unit transposes the difference signal by a first frequency shift to move the difference signal to frequencies above the first cut-off frequency. Further, the processing unit adds the transposed signal and the first electrical signal and the second electrical signal to generate the third electrical signal.

In another embodiment, the portable computing device and/or the application applies a low pass filter to the third electrical signal with a cut-off frequency equal to the first cut-off frequency to obtain a sum signal corresponding to the sum of the first electrical signal and the second electrical signal. The portable computing device and/or the application further applies a high pass filter to the third electrical signal with a cut-off frequency somewhere in the range between the first cut-off frequency and the first frequency shift. The portable computing device and/or the application transposes the high-pass filtered signal back to the original frequencies below the first cut-off frequency to obtain the difference signal. Further, the portable computing device and/or the application adds the difference signal and the sum signal, to obtain the first electrical signal. The portable computing device and/or the application subtracts the difference signal from the sum signal to obtain the second electrical signal.

Disclosed herein is a data processing system. The data processing system includes a processor and program code means for causing the processor to receive an electrical signal from a headset through an input channel. The headset comprises a first speaker, a first microphone, a second speaker and a second microphone. The electrical signal is comprised of a first electrical signal output by the first microphone and a second electrical signal output by the second microphone. The program code means causes the processor to separate the electrical signal into the first electrical signal and the second electrical signal. The program code means causes the processor to process the first electrical signal and the second electrical signal to compensate for the hearing loss of the individual of the data processing system. The program code means causes the processor to communicate the processed first signal to the first speaker through a first channel, and the second signal to the second speaker through a second channel.

The program code means can be installed in any portable computing devices such as a mobile communication device, a portable music player, a personal digital assistant (FDA), or a laptop. Consequently, the individual can use a binaural headset with the portable computing devices to use the portable computing device as a hearing aid.

Disclosed herein is a hearing instrument. The hearing instrument includes a stereo headset and a portable computing device. The stereo headset includes a first earpiece, a second earpiece, a processing unit and a connector. The first ear piece includes a first speaker and a first microphone. The second earpiece includes a second speaker and a second microphone. The first microphone outputs a first electrical signal. The second microphone outputs a second electrical signal.

The processing unit is coupled to the first earpiece and the second earpiece. The processing unit receives the first electrical signal and the second electrical signal. The processing unit combines the first electrical signal and the second electrical signal into a third electrical signal. The processing unit communicates the third electrical signal to the portable computing device via an output channel. The connector is coupled to the first earpiece and the second earpiece, to connect the stereo headset to the portable computing device. The connector includes a first speaker contact, coupled to the first speaker through a first channel (e.g. to propagate a first processed electrical signal from the portable computing device). The connector also includes a second speaker contact coupled to the second speaker through a second channel (e.g. to propagate a second processed electrical signal from the portable computing device). The connector further includes a microphone contact coupled to the processing unit through the output channel (e.g. to propagate the third electrical signal to the portable computing device).

The portable computing device may include an application (APP). The portable computing device and/or the application separates the third electrical signal into the first electrical signal and the second electrical signal. The portable computing device and/or the application processes the first electrical signal and the second electrical signal to compensate for a hearing loss of the individual of the audio system. The portable computing device and/or the application communicates the processed first electrical signal to the first speaker through the first channel, and the processed second electrical signal to the second speaker through the second channel.

The hearing instrument can be used as a hearing aid by the individual with hearing difficulties, in addition to other functions of the portable computing device. It is an advantage that the individual does not have to use the known hearing aid in conjunction with the portable computing devices.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanying figures, which show by way of illustration how the invention may be practiced.

FIG. 1shows an exemplary audio system100, in accordance with an embodiment of the present disclosure. The audio system100includes a headset102and a computing device104. The headset102includes an earpiece114A, an earpiece114B and a signal processing unit110. The earpiece114A includes a microphone106A and a speaker108A co-located to each other. The earpiece114B includes a microphone106B and a speaker108B co-located to each other. The microphones106A-B and the speakers108A-B may be communicatively coupled to the signal processing unit110. The microphones106A-B capture acoustic signals at audible frequencies. The microphones106A-B transmit electrical signals corresponding to the acoustic signals to the signal processing unit110through a wired or wireless communication link. The microphones106-B may be omnidirectional or directional microphones. Each of the earpieces114may include further microphones106, e.g. a total of two or three microphones each, in order to allow direction-dependent processing of the audio signals by combining outputs from two or more of the microphones.

The processing unit110receives the electrical signals from each of the microphones106A-B. In one embodiment, the processing unit110combines the electrical signals to generate a combined electrical signal. The processing unit110communicates the combined electrical signal to the computing device104via a single channel. In another embodiment, the processing unit110processes and communicates the electrical signals to the computing device104through separate channels.

The computing device104includes an application (APP)112. The application112receives and separates the combined electrical signal into corresponding electrical signals. In an embodiment, the application112is a hearing aid application performing substantially all signal processing associated with a hearing aid. For example, the application112processes the separated electrical signals to compensate for a hearing loss of the (respective ears of the) individual of the audio system. The application112may also perform binaural signal processing, noise reduction, such as multi-channel noise reduction, acoustic feedback cancellation, automatic gain control, compression, and the like. The application112communicates the processed electrical signals to the speakers108A-B of the headset102. In one embodiment, the application112communicates the processed electrical signals to the speakers108A-B corresponding to the microphones106A-B at which the electrical signals were generated. Each speaker108A-B may receive electrical signals corresponding to the acoustic signals through a corresponding channel. The speakers108A-B may convert the processed electrical signals to the acoustic signals. The acoustic signals generated as a result of electrical signals at corresponding speakers enable the individual to perceive the directionality of a single or multiple sources of acoustics. In other embodiments, the enhanced electrical signals are communicated to both of the speakers after processing the electrical signals to eliminate distortion.

As described above, the computing device104may use the application112to separate the electric signals received from the headset102and compensate the electrical signals for the hearing loss. The application112as described above may be installed on the computing device104or accessed by the computing device104via a network. Alternatively, the computing device104may include circuitry to separate and compensate the electrical signals from the headset. In another alternative, the computing device104may include the circuitry and the application112to separate and compensate the electrical signals. In one embodiment, the portable computing device and/or the application112may use a hearing profile of the individual to process the electrical signals. The hearing profile may refer to information that includes hearing range of the individual, i.e. the level range between the hearing threshold and the uncomfortable level of the individual. This range is typically frequency-dependent. For example, an individual with a sensorineural hearing loss may not be able to hear sounds of low intensity and may have difficulty in hearing sounds of moderate intensity such as conversational sounds. The hearing range for the individual based on above example may be moderate to loud sound. Using the hearing profile of the individual, the portable computing device and/or the application112may process the electrical signals to compensate for the hearing loss of the individual. The hearing profile may be stored in the computing device104. In another embodiment, the portable computing device and/or the application112may dynamically compute the hearing profile of the individual to process the electrical signals. For example, the portable computing device and/or the application112may provide sound tests to evaluate a hearing ability of the individual of the audio system100to compute the hearing profile. In yet another embodiment, the portable computing device and/or the application112may access and use the hearing profile of the individual stored in a remote server, a storage device, an external device, and the like. Although, the portable computing device and/or the application112is described for separating the combined electrical signal into the electrical signals, and compensating the electrical signals for hearing loss of the individual, one can appreciate that the portable computing device and/or the application112may include other functionalities as well. Some of the other functionalities include, but are not limited to, processing music and voice controlled operations. The portable computing device and/or the application112may include functionalities other than audio processing as well (e.g. image and/or video display or recording, gaming, etc.).

The headset102as described herein may correspond to any headset that includes at least two microphones106A-B. Each microphone may be associated with and placed in proximity of a corresponding speaker of the headset. In one example implementation, the headset102may be a stereo headset. The stereo headset may be designed for binaural capturing of acoustic signals by having at least one microphone at each earpiece. The headset102may be a miniature ear-fitting headset, or a headset of size that substantially encompass ears of the individual or any other headset which can be used for this disclosure. The headset102may be a wired headset that can be communicatively coupled to the portable computing devices such as a portable music player, a mobile communication device, a laptop, Personal Digital Assistant (PDA), and the like, through a connector. In one embodiment, the (wired) headset102may be connected to the computing device using a Tip-Ring-Ring-Sleeve (TRRS) connector, which is a well known type of phone connector. The TRRS connector may support three channels. Two channels may be used for the speakers108A-B and one channel for the microphones106A-B. In one example implementation, the tip of TRRS connector may connect a channel associated with one of the speakers, for example, the speaker108A, while the ring adjacent to the tip may connect a channel associated with another of the speakers, for example, the speaker108B. The second ring adjacent to sleeve and the ring may be a common ground line. The sleeve may connect a channel that is shared by the microphones106A-B. Other types of connectors for communicatively coupling the headset102and the computing device104are contemplated herein. The (wired) headset102may be powered by the computing device104.

Alternatively, the headset102may be a wireless headset such as Digital Enhanced Cordless Telecommunications (DECT) wireless headsets, 2.4 GHz wireless headset, Bluetooth wireless headsets, and the like, that can be communicatively coupled to the electronic device wirelessly. In some examples, the headset may be a wired and wireless headset. The wireless headset may be powered by batteries. The headset102as described above may have active or passive noise cancellation to cancel external noises interfering with the acoustic signals generated by the speakers108A-B.

The computing device104as described herein may be a portable electronic device that is capable of processing the electrical signals received from the microphones106A-B of the headset102and communicating the processed electrical signals to the speakers108A-B of the headset102or produce acoustic signals corresponding to the electrical signals through speakers of the portable electronic device. The computing device104may include, but is not limited to, a mobile communication device (e.g. a SmartPhone), a portable music player, a laptop, a PDA and the like. The computing device104may be an independent component made of hardware, software, or hardware and software that can be implemented in or in conjunction with the computer-based systems. Those skilled in art can appreciate that computing device104may include an operating system as well as various conventional support software and drivers. The application112as described may be implemented as a set of computer related instructions. The computing device104may be configured to execute the set of computer related instructions. The computer readable instructions of corresponding modules and tools may be loaded onto a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions that execute on the computer or other programmable data processing apparatus create means for implementing the functions as described herein. These computer program instructions may also be stored in a computer-readable memory that can direct computing devices or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function. The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the disclosure. The computing device104may be capable of accessing networks or other devices. The computing device104may comprise a user interface, e.g. implemented via a touch sensitive display.

FIG. 2shows a functional block diagram of an exemplary implementation of the signal processing unit110of the audio system100, in accordance with an embodiment of the present disclosure. The signal processing unit110may include, low pass filters204A-B, analog to digital converters206A-B, and a combining unit208. The signal processing unit110receives electrical signals202A-202B from the corresponding microphones106A-B. The low pass filter204A-B may remove frequency components in the corresponding electrical signals202A-B that are higher than a first cut-off frequency. The first cut-off frequency may be set based on a sampling rate at which the electrical signals202A-B may be sampled prior to combining the electrical signals202A-B. In one example implementation, the first cut-off frequency may be set at a frequency less than or equal to one fourth of the sampling rate. For example, when the sampling frequency is 48 kHz, the first cut-off frequency may be set to 10 kHz.

The analog to digital converter206may convert the analog filtered electrical signals202A-B into digital signals. The analog to digital converter206may sample the analog filtered signals202A-B at the sampling rate. The sampling rate may be set such that the electrical signals can be combined to share the channel. The combining unit208combines the digital electrical signals into a combined electrical signal210. The combining unit208generates the combined electrical signal210using various combination techniques. Two example techniques are described inFIG. 4AandFIG. 4B. The combining unit208preferably comprises a digital to analog converter (not shown) to convert the combined electrical signal210to an analog signal. The combining unit208may communicate the digital or analog combined electrical signal210to the computing device104via a single channel.

ThoughFIG. 2illustrates an embodiment, where analog to digital conversion is performed after applying a low pass filter to the first and second electrical signals, it need not be so. In alternative embodiments, the first and second electrical signals may first be converted to digital signals using the analog to digital converters. The low pass filters may be designed in the digital domain and applied to the digital versions of the first and the second electrical signals. In further alternative embodiments, the analog to digital converters206and the digital to analog converter in the combining unit208may be omitted and the combining of the electrical signals may be performed entirely in the analog domain.

FIG. 3shows a functional block diagram of an exemplary implementation of the computing device104of the audio system100, in accordance with an embodiment of the present disclosure. The computing device104includes the application112. The application112separates the combined electrical signal210into the electrical signals and processes the electrical signals to compensate for hearing loss of the individual of the audio system100. The application112may include a separating module304, and a processing module306. The separating module304may receive the combined electrical signal210from the signal processing unit110. The separating module304may separate the combined electrical signal210into the electrical signals202A-B. Two exemplary techniques for separating the electrical signals are described inFIG. 4AandFIG. 4B.

The separating module304may communicate the electrical signals202A-B to the processing module306. The processing module306may process the electrical signals to compensate for the hearing loss of the individual. The processing module306includes an expansion module308, a compression module310, an automatic gain control module312, a noise reduction module314and a feedback cancellation module316. The expansion module308may apply a level expansion in the lower portion of the hearing range of the individual. The expansion may be linear or non-linear. The expansion module308may apply the level expansion to the electrical signals202A-B having levels lower than a first threshold level. The first threshold level may be obtained from the hearing profile of the individual or dynamically determined. In one embodiment, the level expansion may be frequency dependent, i.e., the different gain factors may be applied at different frequencies based upon the individual's hearing loss at these frequencies.

The compression module310may apply a level compression to middle and upper portions of the hearing range of the individual. The compression module310may compress the levels of the electrical signals202A-B when the sound pressure is above a second threshold level (threshold knee-point (TK)). An appropriate compression ratio may be applied to compress the levels of the electrical signals beyond the second threshold level. In one example implementation, the compression ratio may be kept high to avoid discomfort due to loud sounds. The second threshold may be determined from the hearing profile or may be dynamically computed. The compression module310may be programmed to have minimal or standard Attack Time (AT) and Release (or recovery) time (RT). The AT is the time delay that occurs between the onset of an input signal loud enough (the input signal exceeds the TK) to activate compression and the resulting reduction of gain to a target value. The RT is the time delay that occurs between the offset of the input signal falling below the TK and the resulting increase of gain to its target value. The compression module310may incorporate adaptive or variable release time. The automatic gain control module312may control the gain of the electrical signals202A-B based on the level of the electrical signals202A-B. In one embodiment, the automatic gain control module312may incorporate an input-controlled compression (AGC-I), where the level of the electrical signals202A-B (input) is detected and compression is activated based on the level. In another embodiment, the automatic gain control module312may incorporate output-controlled compression (AGC-O), where the level of the electrical signals202A-B (output) is detected and compression is activated based on the level. The functioning of AGC-I and the AGC-O is well known in the art and hence a detailed explanation is not provided herein for reasons of brevity. The noise reduction module314reduces noise in the electrical signals202A-B. The noise may be an environment noise or a circuit related noise. The noise reduction module314may use noise reduction algorithms that are well known in art or proprietary noise reduction algorithms to reduce the noise in the electrical signals202A-B. The feedback cancellation module316may identify any feedback noise in the electrical signals202A-B due to feedback of the speaker sound into the microphones. The feedback cancellation module316may apply notch filtering or feedback canceling techniques to reduce such feedback noise. The processing module306may also perform binaural processing of the electrical signals202A-B to enable the individual to perceive the spatial directions to the source(s) of the sound.

The processing module306provides increased gain for soft sounds, maintains medium sounds at a comfortable loudness, and reduces gain for louder inputs to assure listening comfort for the individual. The computing device104communicates the electrical signals202A-B to the speakers108A-B via corresponding channels.

Although, the application112is described for separating the combined electrical signals, and compensating the electrical signals, one can appreciate that the application112can also process audio such as music, computing device prompt sounds, and the like, to compensate for hearing loss of the individual. The application112may communicate the compensated audio to the speakers108A-B. Although the application112is described for performing the functions of separating and processing the electrical signals202A-B, one can appreciate that the application112can have other functionalities as well.

FIG. 4A-Bshows exemplary techniques for combining and separating the electrical signals, in accordance with various embodiments of the present disclosure.FIG. 4Aillustrates a combining block450and a separating block450. The combining block450represents an operation for combining electrical signals452A-B (performed by the combining unit208). The separating block450represents a separation operation for separating a combined electrical signal462into the electrical signals452A-B (performed by the separating module304).

In the combining operation450ofFIG. 4A, the combining unit208may receive the electrical signals452A-B from the corresponding analog to digital converters206A and206B, respectively. According to one embodiment, the combining unit208may transpose (block402inFIG. 4B) the electrical signal452A by a first frequency shift to frequencies above the first cut-off frequency. The combining unit208may add (block404inFIG. 4A) the transposed signal454A and the digital electrical signal452B to generate the combined electrical signal462. In the separating operation460, the separating module304applies a low pass filter (block406inFIG. 4A) with a cut-off frequency equal to the first cut-off frequency (the cut-off frequency at which the electrical signals452A-B were low pass filtered using the low pass filters204A-B) to the combined electrical signal462. The signal obtained as a result of application of the low pass filter406, is the electrical signal452B. The separating module304also applies a high pass filter (block408inFIG. 4A) with a cut-off frequency somewhere in the range between the first cut-off frequency and the first frequency shift to the combined electrical signal462. The resultant filtered signal is the transposed signal454A. The separating module304transposes (block410inFIG. 4A) the high passed filtered signal back to the original frequencies below the first cut-off frequency. The resulting signal is the electrical signal452A. Thus, the electrical signals452A-B are separated. The electrical signals452A-B are communicated for further processing.

FIG. 4Billustrates a different, but related technique for combining and separating electrical signals.FIG. 4Billustrates a combining block470and a separating block480. The combining block470represents an operation for combining the electrical signals452A-B performed by the combining unit208. In combining operation470, the combining unit208may receive the electrical signal452A-B. The combining unit208may generate a difference signal456by subtracting (block412inFIG. 4B) the second electrical signal452B from the first electrical signal452A. Subsequently, the combining unit208may transpose (block414inFIG. 4B) the difference signal456by a first frequency shift to frequencies above the first cut-off frequency to generate a transposed signal458. The combining unit208adds (block416inFIG. 4B) the transposed signal458and the electrical signals452A-B to generate the combined electrical signal462.

The separating block480represents a separation operation for separating the combined electrical signal462into the electrical signals452A-B (performed by the separating module304). The separating module304receives the combined electrical signal462. The separating module304may apply a low pass filter (block418inFIG. 4B) with a cut-off frequency equal to the first cut-off frequency (the cut-off frequency with which the electrical signals452A-B were low pass filtered using the low pass filter204A-B) to the combined electrical signal462. The signal obtained as a result of application of the low pass filter406is a sum signal464(a signal representing a sum of the electrical signals452A-B). The separating module304may apply a high pass filter (block420inFIG. 4B) with a cut-off frequency somewhere in to range between the first cut-off frequency and the first frequency shift to the combined electrical signal462to obtain the transposed signal458. The separating module304may transpose (block422inFIG. 4B) the obtained transposed signal458back to the original frequencies below the first cut-off frequency to obtain the difference signal456. The separating module304may add (block424inFIG. 4B) the difference signal456and the sum signal464to obtain the electrical signal452A. The separating module304may subtract (block426inFIG. 4B) the difference signal456from the sum signal464to obtain the electrical signal452B. The technique of combining and separating the electrical signals452A-B described inFIG. 4Bcauses even distribution of the noise and processing artifacts between the two electrical signals452A-B.

Although two example techniques are provided for combining and separating the two electrical signals, it should be appreciated that other techniques for combining and separating the signals are contemplated herein. The disclosed techniques, as well as other suitable techniques, may be extended to combine and separate more than two, e.g. four or six or even more electric signals from corresponding microphones in the headset. This allows for forming and processing directionally dependent microphone signals in the portable computing device in order to provide sounds with increased signal-to-noise ratio to the user.

FIG. 5shows a hearing instrument500designed according to one or more embodiments of the current disclosure. The hearing instrument500includes a stereo headset502, and a mobile communication device504. The stereo headset502includes a left earpiece506, a right earpiece508, a signal processing unit514and a TRRS connector516. The left earpiece506includes a microphone510A and a speaker512A co-located to each other. The right earpiece508includes a microphone510B and a speaker512B co-located to each other. The signal processing unit514communicatively couples the set of microphones510A-B and the speakers512A-B with the TRRS connector516. In one embodiment, a tip518of the TRRS connector516may be a speaker contact electrically coupling a channel associated with the speaker512A. A ring520adjacent to the tip518of the TRRS connector516may be another speaker contact electrically coupling a channel associated with the speaker512B. A second ring522adjacent to a sleeve524and the ring520may be a ground line. The sleeve524may be a microphone contact electrically coupling a channel associated with the microphones510A-B. Since there is more than one microphone and one channel for the microphones510A-B, the signal processing unit514is configured to combine the electrical signals and to communicate a combined electrical signal via the channel connecting the microphone contact. The TRRS connector516may be designed to be physically and electrically couple with a corresponding TRRS port526. The TRRS port526may be located on the mobile communication device504. Having the microphones510A-B co-located with corresponding speakers512A-B of the stereo headset502enables the hearing instrument500for realizing a binaural hearing aid.

The signal processing unit514may be comprised in a housing integral with the TRRS connector516, or alternatively be comprised in one of the earpieces506,508, or as a further alternative comprised in a separate housing. The housing signal processing unit514may include a volume control, one or more push buttons and one or more visual indicators, such as a Light Emitting Diode (LED). The volume control may be used to adjust the volume of the signals sent to the speakers512. Alternatively, an electric output signal of the volume control may be coded onto the combined electric signal and correspondingly be decoded in the mobile communication device504, e.g. in the application, to provide a user control input to the hearing aid signal processing. Outputs of the one or more pushbuttons may be coded/decoded in a similar way to provide user controllable functions in the hearing aid or in the mobile communication device504, such as e.g. hearing-aid program change or accepting a phone call. Furthermore, the mobile communication device504may launch the application upon detecting such coded user input in the microphone input. Also, the headset may function as a standard headset that just provides one of the microphone signals or a sum of these to the connector when a power signal, or another suitably coded signal, from the mobile communication device504is absent. Alternatively, a user interface for controlling the hearing aid functions may be implemented in the mobile communication device504(e.g. as an APP, e.g. using activation elements, e.g. a touch sensitive display, of the mobile communication device).

The signal processing unit514may be supplied with power by a battery, e.g. a rechargeable battery, comprised in the same housing as the signal processing unit514. Alternatively, the signal processing unit514may be supplied with power from the mobile communication device504, e.g. by means of a DC voltage applied to the speaker contacts of the TRRS port526.

The microphones510A-B capture acoustic signals and convert the captured acoustic signals into electrical signals. The signal processing unit514receives the electrical signals from each of the microphones510A-B. In embodiments, the signal processing unit514processes the electrical signals to generate a combined electrical signal. As described above, the signal processing unit514may process the electrical signals by applying a low pass filter with a first cut-off frequency, convert the filtered electrical signals into digital signals, combine the digitized electrical signal into the combined electrical signal, and convert the combined electrical signal into an analog signal. The first cut-off frequency is set to a frequency less than one fourth of the sampling frequency. To elaborate with an example, the sampling frequency may be 48 kHz and the first cut-off frequency may be set to 10 kHz. The signal processing unit514, thus, applies low-pass filter on the signals to retain frequencies below 10 kHz. Subsequently, the signal processing unit514may convert the analog electrical signals to digital electrical signals. In one example implementation, the signal processing unit514may frequency transpose the digital signal corresponding to the microphone510A (of the left earpiece506) by, for example, 10 kHz to the range between 10 kHz and 20 kHz. The signal processing unit514may add the transposed signal and the digital signal corresponding to the microphone510B (of the right earpiece508) to generate the combined electrical signal. The signal processing unit514converts the combined electrical signal into an analog signal. The signal processing unit514may communicate the analog combined electrical signal to the mobile communication device504via a single channel (in the current example, via the microphone contact (sleeve524) of TRRS connector516).

The mobile communication device504may include an application528that processes the combined electrical signal. The application528receives and separates the combined electrical signal into corresponding electrical signals. In the current example, the application528may apply a low pass filter with a cut-off frequency equal to the first cut-off frequency (that is 10 kHz) to the combined electrical signal. The filtered signal is the electrical signal corresponding to the microphone510B. The application528may apply a high pass filter with a cut-off frequency somewhere in the range between the first cut-off frequency and the first frequency shift (in this case 10 kHz as the first cut-off frequency and the first frequency shift both equal 10 kHz) to the combined electrical signal to obtain the transposed signal. The application528may transpose the obtained transposed signal back to the original frequencies below the first cut-off frequency (that is 10 kHz), to obtain the electrical signal corresponding to the microphone510A. The transposition during separation is thus preferably opposite in direction and equal in magnitude to the transposition applied during combining.

The application528communicates the processed electrical signals to the speakers512A-B through corresponding channels. The speakers512A-B may convert the processed electrical signals to acoustic signals. The acoustic signals generated as a result of electrical signals at corresponding speakers enable the individual to perceive the direction to a single or multiple sources of acoustics. In one embodiment, the application528may use the hearing profile of the individual to process the electrical signals from the stereo headset502. Alternatively, the application528dynamically process the electrical signals based on sound tests conducted through the stereo headset502.

The mobile communication device504may detect the stereo headset502when the stereo headset502is plugged into the mobile communication device504. Responsive to detecting, the mobile communication device504may provide an option to the individual to select the purpose of the stereo headset502. Responsive to selection of an option of hearing aid, the application528may be activated. Alternatively, the application528in the mobile communication device504may process the electrical signals from the stereo headset502without requiring any individual's action. The stereo headset502may be powered by the mobile communication device504.

In an embodiment, the headset is or comprises a wired connection, e.g. comprising a phone connector or audio jack, e.g. mini-jack, or a mini- or micro-USB connector. This is of a particular advantage in applications where delay/latency is an important feature and should be minimized. Wireless links typically incur larger delays due to various processing involved in the (e.g. digital) wireless transmission and reception, e.g. coding, decoding, error correction, etc. Alternatively, the use of a wired connection allows the use of additional processing algorithms (such as e.g. noise reduction and compression) to improve the audio quality without increasing the processing delay (compared to a wireless solution).

Although some embodiments have been described and shown in detail, the invention is not restricted to them, but may also be embodied in other ways within the scope of the subject matter defined in the following claims. In particular, it is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present invention. For example, the ear pieces are generally described as comprising speakers, typically referring to loudspeakers in a normal sense (adapted for creating vibrations in air). Alternatively, an ear piece may comprise a vibrator, e.g. of a bone anchored hearing aid, specifically adapted for creating vibrations in a solid, e.g. human bone, or liquid material.

In device claims enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used to advantage.