Hearing instrument and method for operating such a hearing instrument

Abstract

A hearing instrument (4) is specified, comprising a housing (8) worn behind the ear in a designated wearing position, an earpiece (10) to be inserted into the user's ear canal, and a flexible connecting piece (14) that connects the housing (8) to the earpiece (10). The hearing instrument (4) further comprises an output transducer (12) for converting an output audio signal (O) into a sound signal to be output to the user, as well as a capacitive sensor (26) that has a control and evaluation circuit (28) and two sensor electrodes (30, 32) electrically connected thereto. One of the sensor electrodes (30) is arranged in the housing (8), while the other sensor electrode (32) is arranged in the connecting piece (14) and / or the earpiece (10).

Description

The invention relates to a hearing instrument having a housing worn behind the ear of a user in a intended wearing position, an earpiece to be inserted into the auditory canal of an ear and a flexible connecting piece. The invention further relates to methods for operating such a hearing instrument.A hearing instrument is generally referred to as an electronic device that supports the hearing ability of a person wearing the hearing instrument (which is referred to below as a "wearer" or "user"). In particular, the invention relates to hearing instruments which are configured to completely or partially compensate for a hearing loss of a user who is impaired by hearing. Such a hearing instrument is also referred to as a "hearing device". In addition, hearing instruments exist which protect or improve the hearing capacity of normally hearing users, for example enable improved speech comprehension in complex hearing situations. The hearing instruments also include wireless earphones (worn in or on the ear), in particular so-called ear plugs and headsets.Hearing instruments in general, and hearing aids in particular, are usually designed to be worn on the head and here in particular in or on an ear of the user, in particular as behind-the-ear devices (also referred to as BTE devices according to the English term "behind the ear") or in-the-ear devices (also referred to as ITE devices according to the English term "in the ear"). With regard to their internal structure, hearing instruments regularly have at least one (acousto-electric) input transducer, a signal processing unit (signal processor) and an output transducer. In operation of the hearing instrument, the or each input transducer receives airborne sound from the surroundings of the hearing instrument and converts this airborne sound into an input audio signal (i.e. an electrical signal which carries information about the ambient sound). In the signal processing unit, the or each input audio signal is processed (i.e. modified with regard to its sound information) in order to support the hearing ability of the user, in particular in order to compensate for a hearing loss of the user. The signal processing unit outputs a correspondingly processed audio signal to the output converter. In modern hearing instruments, the signal processing, in addition or as an alternative to a frequency-dependent amplification of the input audio signal, regularly comprises a multiplicity of further functions, for example beamforming (i.e. directional damping), active noise suppression, wind noise suppression. Feedback attenuation, binaural processing to assist in spatial listening, dynamic and / or spectral compression, etc.In most cases, the output transducer is designed as an electro-acoustic transducer, which converts the (electrical) output audio signal back into an airborne sound, wherein this airborne sound-modified with respect to the ambient sound-is emitted into the auditory canal of the user. In the case of a hearing instrument worn behind the ear, the output transducer, also referred to as "receiver" ("receiver"), is usually integrated outside the ear in a housing of the hearing instrument. The sound emitted by the output transducer is in this case conducted by means of a sound tube into the auditory canal of the user. Alternatively, the output transducer may also be disposed in the ear canal and thus outside the behind-the-ear worn housing. Such BTE devices are also referred to as RIC devices (according to the English term "receiver in canal"). Hearing instruments worn in the ear that are dimensioned so small that they do not protrude outward beyond the auditory canal are also referred to as CIC devices (according to the English term "completely in canal").In further designs, the output transducer can also be designed as an electromechanical transducer, which converts the output audio signal into structure-borne sound (vibrations), wherein this structure-borne sound is emitted, for example, into the skull bone of the user.A "hearing system" is generally referred to as an arrangement of devices and, if appropriate, other structures which provide functions for operating a hearing instrument. In the simplest case, the hearing system consists only of the hearing instrument itself. As a rule, however, the hearing system comprises, in addition to the hearing instrument, at least one peripheral device which, during operation of the hearing instrument, interacts with the latter, for example a further hearing instrument for the other ear of the user, a remote control, an external microphone, a programming device for the hearing instrument or a charger. In modern hearing systems, furthermore, a software application is often provided in addition to the hearing instrument, which can be installed on a (in particular mobile) computer, e.g. a smartphone or a tablet computer, and contributes functions for operating the hearing instrument (e.g. remote control, programming, firmware updates, data protection, complex signal processing and / or Internet connection). The computer on which this software application (referred to below as "hearing app") is installed, indeed, likewise represents a peripheral device of the hearing instrument during operation of the hearing instrument, which peripheral device is connected to the hearing instrument by data transmission technology. However, the computer usually does not belong to the hearing system itself, in so far as it is manufactured and sold independently of the components of the hearing system and is usable for a plurality of further applications not connected to the hearing system. The computer (i.e. in particular the smartphone or the tablet computer of the user) is rather used by the hearing app only as an external resource for computing power, storage space and communication services.The proper functioning of a hearing instrument and thus the benefit that the hearing instrument brings to its wearer during daily operation depend critically on the seat of the housing and the earpiece on or in the ear of the wearer. In other words, the hearing instrument can achieve the intended task satisfactorily only if the housing and the earpiece are arranged behind or in the ear in the respectively provided wearing position.This is due, on the one hand, to the signal processing of the hearing instrument being matched to a specific acoustic situation at the location of the or each microphone of the hearing instrument, e.g. to a specific orientation of the (respective) microphone with respect to the head and to a specific acoustic shading of the microphone by the ear. If the housing of the hearing instrument is worn behind the ear, deviating from the intended wearing position, the acoustic situation to which the microphone is exposed and thus--in the case of a given ambient noise--also the input audio signal recorded by the microphone thereby change. The signal processing tuned to another acoustic situation can no longer process the input audio signal picked up by the malpositioned microphone in an optimum manner. This can be expressed, for example, in that, as a result of misaligned beamforming, the useful signal desired by the user (e.g. the voice of a conversation partner) is attenuated instead of an undesired background noise, that active noise suppression no longer works to a satisfactory extent, etc.As an undesirable effect of malpositioning of the earpiece, a reduced acoustic sealing of the ear canal by the earpiece can occur, which can lead to undesirable side effects, e.g. an increased noise level or the occurrence of acoustic feedback. In a CTE device, misalignment of the housing can also cause such effects, for example if the connection piece is under mechanical tension or is bent too much as a result of the incorrect positioning of the housing. In this case, the coupling may exert a mechanical load on the earpiece which gradually pulls the earpiece wholly or partly out of the ear or otherwise deflects it out of the correct fit in the ear canal.Against this background, the object of the invention is to enable an improved checking of the proper seating of a hearing instrument.With regard to a hearing instrument, this object is achieved according to the invention by the features of claim 1. With regard to a method for operating a hearing instrument, the above object is achieved according to the invention by the features of claim 6.The invention is based on a hearing instrument having a housing which is to be worn behind the ear of a user in a provided wearing position. The hearing instrument additionally comprises an earpiece to be placed in the ear of the user, a flexible connecting part which connects the housing and the earpiece and an output transducer for converting an (electrical) output audio signal into a sound signal to be output to the user. The output transducer is preferably formed by an electro-acoustic transducer, i.e. a loudspeaker ("listener"). The hearing instrument is thus a BTE device, and specifically optionally a classic hearing instrument with an output transducer arranged in the housing, or an RIC device in which the output transducer is arranged in the earpiece. In the former case, the connector is formed by a sound tube that directs the sound produced by the output transducer to the earpiece. In the latter case, the connector comprises an electrical connection cable through which the output audio signal is fed to the output transducer disposed in the earpiece.In all of the embodiments described above, the hearing instrument further comprises a capacitive sensor which comprises a control and evaluation circuit (also referred to below as "sensor controller" or "sensor controller") and (at least) two sensor electrodes electrically connected thereto. According to the invention, one of the two sensor electrodes is arranged in the housing. The other sensor electrode, on the other hand, is arranged in the connecting piece and / or the earpiece.The capacitive sensor can be used to detect, in general, dielectrically effective or electrically conductive structures in the vicinity of the sensor, namely, in particular, body structures such as, for example, the head and the ear of the user. This makes use of the fact that the (capacitive) sensor signal output by the capacitive sensor, due to the variety of surrounding body structures of the user, depends in a characteristic manner on the seat of the housing and of the connecting part and, if appropriate, of the earpiece on or in the ear. In other words, the sensor signal output by the capacitive sensor changes characteristically when the user displaces the hearing instrument (in particular the housing thereof) relative to the ear. As recognized, the correct seat of the hearing instrument in the intended wearing position can be recognized on the basis of this dependence of the capacitive sensor signal. The distribution of the two sensor electrodes of the capacitive sensor to the housing on the one hand and the connecting part and / or the earpiece on the other hand has proven to be particularly advantageous in this case, since with this arrangement of the sensor electrodes a particularly precise and effective detection of any malpositioning of the hearing instrument is possible. In particular, it can be effectively determined with this whether the connecting piece, when the hearing instrument is inserted, runs close to the ear as provided, from which it can in turn be concluded that the housing and the earpiece are in position.The control and evaluation circuit (sensor controller) of the capacitive sensor is preferably configured to apply an electrical alternating voltage (also referred to as "(capacitive) sensor voltage") to at least one of the sensor electrodes and to measure a response signal generated under the action of this alternating voltage, which response signal is characteristic of an electrical capacitance assigned to the sensor electrode. The sensor controller is preferably designed as a microcontroller. The functionality of the sensor controller is implemented in this case as software. However, within the scope of the invention, the sensor controller can also be designed as a non-programmable (analog or digital) electrical circuit. In both cases, the sensor controller can be designed as an independent component (e.g. as a separate integrated circuit) or integrated together with other functions in a larger structural unit, as desired within the scope of the invention.In order to exclude possible interference of the sound signal output by the output transducer by the capacitive sensor, the sensor controller is preferably configured to output the sensor voltage as an alternating voltage with a frequency which exceeds the audible frequency spectrum, in particular does not fall below 20 kHz. In a preferred embodiment, the frequency of the sensor voltage is between 20 kHz and 10 MHz, in particular between 20 kHz and 100 kHz, for example 60 kHz.Within the scope of the invention, the capacitive sensor can be based basically on one of two functional principles that are conventional per se.According to a first functional principle, which is referred to as "one-electrode measurement" or "self-capacitance measurement" (self-capacitance sensing), for example, the sensor controller measures the response signal on the same sensor electrode to which it applies the sensor voltage. The sensor electrodes of the capacitive sensor are actuated by the sensor controller independently of one another with the sensor voltage. As a capacitance-dependent response signal, the sensor controller measures, for example, the current flowing on this sensor electrode under the effect of the sensor voltage or the frequency of the sensor voltage at each sensor electrode (wherein use is made of the fact that the respective sensor electrode is part of an oscillating circuit with a resonance varying depending on the capacitance). In all cases, the response signal is characteristic here for the (electrical) capacitance of each sensor electrode with respect to an external ground potential. The counterelectrode of the capacitor, whose capacitance the sensor measures, is thus the external mass potential, which is formed here, for example, by the body of the user, in the "one-electrode measurement".According to a second functional principle, which is referred to as "two-electrode measurement", "transmitter-receiver principle" or "relative capacitance measurement" (mutual capacitance sensing), for example, the sensor controller applies the sensor voltage to a first sensor electrode (transmitting electrode) and measures the response signal to the other sensor electrode (receiving electrode). In this case, the sensor controller measures, for example, the current generated in the receiving electrode by an electric field under the effect of the sensor voltage as a capacitance-dependent response signal. The response signal in this case is characteristic of the (electrical) capacitance of the capacitor which is formed by the two sensor electrodes. In the "two-electrode measurement", the body of the user acts as a disturbing potential, which changes the capacitance of the capacitor formed by the two sensor electrodes and is detected thereby.The capacitive sensor of the hearing instrument according to the invention is preferably designed as a "relative capacitance sensor" (mutual capacitance sensor), since in this embodiment the sensor control can be implemented particularly easily in terms of circuit technology; in a particularly simple embodiment the sensor control comprises in this sense a single-channel evaluation circuit, i.e. has only a single sensor input for measuring a single response signal.As mentioned above, in preferred embodiments, the hearing instrument is designed as an RIC device with an output transducer (in particular an electro-acoustic output transducer) arranged in the earpiece. The electrical connecting cable contained in the connector, via which cable the output audio signal is fed to the output converter, is preferably used here as one of the sensor electrodes of the capacitive sensor. Within the scope of the invention, the electrical signal lines of the connecting cable, via which the output audio signal is supplied to the output converter, can be used as a sensor electrode of the capacitive sensor. Alternatively, the connecting cable contains, in addition to the signal lines, a separate electrical conductor which is used (in particular exclusively) as a sensor electrode. In addition or as an alternative to the use of the connecting cable as a sensor electrode, the output transducer (in particular a metallic housing of the output transducer) is used as one of the sensor electrodes of the capacitive sensor. In an expedient configuration, the connecting cable and the output transducer are short-circuited to one another to form a single sensor electrode; in particular, the sensor electrode is formed here by a ground conductor or a shield conductor of the connecting cable, which is short-circuited to the metallic housing of the output transducer. Alternatively, however, it is also conceivable within the scope of the invention that the connecting cable and the output transducer are used within the scope of the capacitive sensor as different sensor electrodes, in particular independently controlled from one another.In further embodiments of the invention, the hearing instrument is, as likewise mentioned above, designed as a classic BTE device, wherein the output transducer is arranged in the housing. The connecting piece is designed as a hollow sound tube which serves to conduct the sound signal generated by the output transducer, which is always designed electro-acoustically in this case, to the earpiece. One of the sensor electrodes of the capacitive sensor is arranged in this sound tube, e.g. in the form of a wire or wire mesh or wire mesh or wire mesh guided in the sound tube or embedded in the wall of the sound tube, or in the form of an electrically conductive film or coating applied to the inner wall of the sound tube.A further embodiment of the invention relates to a hearing system which comprises the hearing instrument according to the invention (in particular in one of the variants described above) and a seat control unit. The seat control unit is configured to check the seat of the hearing instrument on the ear of the user on the basis of a sensor signal output by the capacitive sensor. The seat control unit, which is optionally implemented as a software module or as a non-programmable electronic circuit, preferably carries out this check by comparing the sensor signal output by the capacitive sensor with a stored reference value. Since each user has an individual head and ear shape, the reference value is preferably also determined individually for the respective user. In an alternative embodiment, the seat control unit comprises a neural network to which the sensor signal of the capacitive sensor is supplied and which is taught in particular individually to the respective user in order to check the seat of the hearing instrument on the basis of the sensor signal. The seat control unit is preferably integrated in the hearing instrument. In this case, the hearing system can also consist only of the hearing instrument itself equipped with the seat control unit. Alternatively, the seat control unit is arranged outside the hearing instrument, e.g. in a peripheral device or a software application (hearing app) of the hearing system.The seat control unit is further configured to, upon detection of a deviation of the seat from the intended wearing position, cause the output of a message that indicates to the user the deviating seat of the housing. This message is preferably displayed on a peripheral device by outputting a text message or a graphical indication (for example in the form of a schematic illustration of the hearing instrument housing arranged on the ear), for example by the hearing app assigned to the hearing instrument on the display of a smartphone of the user. Additionally or alternatively, the message is output by the hearing instrument itself, e.g. in the form of a signal tone, a voice message output via the listener of the hearing instrument or by a tactile signal (e.g. vibration).In a further embodiment, the seat control unit is configured to set at least one signal processing parameter of the hearing instrument on the basis of the capacitive sensor signal output by the capacitive sensor in order to adapt the signal processing (i.e. the function of the signal processor) of the hearing instrument to the seat of the housing. In particular, the seat control unit adjusts the orientation of a beam former of the hearing instrument in such a way that a detected deviation of the seat of the housing from the intended wearing position is compensated.The method according to the invention uses the hearing instrument according to the invention in one of the embodiments described above. The above details regarding embodiment variants and components of the hearing instrument and the associated effects and advantages therefore also apply analogously to corresponding embodiments of the method, and vice versa.In the course of the method according to the invention, a capacitive sensor signal is determined as a measure for the seat of the housing and of the connecting part on the user's ear (and optionally the seat of the earpiece in the user's ear) using the sensor electrodes of the capacitive sensor of the hearing instrument according to the invention distributed over the housing and the connecting part and / or the earpiece. When a deviation of the seat from the intended wearing position of the housing or of the connection piece and / or of the earpiece is detected, a message indicating the deviating seat of the hearing instrument is output. Additionally or alternatively, at least one signal processing parameter of the hearing instrument is set on the basis of the capacitive sensor signal output by the capacitive sensor in order to adapt the signal processing of the hearing instrument to the seat of the hearing instrument.Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Shown therein are: FIG. 1 shows a schematic representation of a hearing system with a hearing instrument and a software application (hearing app) installed in a smartphone of the user, wherein the hearing instrument has a housing that is portable behind an ear of a user, an earpiece to be inserted into the auditory canal of the user with an electro-acoustic output transducer (listener) integrated therein and a flexible connecting part that mechanically and electrically connects the housing to the earpiece, and wherein the hearing instrument has a capacitive sensor that comprises a first sensor electrode arranged in the housing and uses a connecting cable guided in the connecting part as second sensor electrode, FIG. 2 shows a schematic representation of an embodiment variant of the hearing instrument, in which the sensor electrodes of the capacitive sensor are operated as transmitting or receiving electrode, and FIG. 3 shows a representation according to FIG. 2 of a further embodiment variant of the hearing instrument, in which the sensor electrodes of the capacitive sensor are operated as independently independent sensor electrodes.Parts and sizes corresponding to one another are always provided with the same reference numerals in all figures.FIG. 1 shows a roughly schematic representation of a hearing system 2, which is formed from a hearing instrument 4 and an associated software application (hearing app 6).The hearing instrument 2 is, for example, a hearing device, i.e. a hearing instrument configured to support the hearing capacity of a user who is impaired by hearing. In the embodiment shown here, the hearing instrument 2 is designed as an RIC device. It accordingly comprises a housing 8 which is worn as intended behind an ear of a user, and an earpiece 10 which is inserted as intended into the auditory canal of the user, wherein an electroacoustic output transducer (earpiece 12) is integrated in the earpiece 10. The hearing instrument 2 further comprises a flexible connecting piece 14 which mechanically connects the housing 8 to the earpiece 10. In the case of the RIC device shown in Figure 1, the connector 14 includes an electrical connection cable 16 for the receiver 12.Within a housing 8, the hearing instrument 4 has the following components:• at least one microphone 18 (in the example shown two microphones 18) as input transducer,• a (in particular digital) signal processor 20,• a battery 22,• a wireless communication device 24 having - not explicitly shown - an RF antenna and a transmitting and receiving unit (transceiver) electrically connected thereto, and• a capacitive sensor 26 which is formed from a control and evaluation circuit (sensor controller 28) and a plurality of (in the exemplary embodiment shown two) sensor electrodes 30 and 32.During normal operation of the hearing instrument 4, the microphones 18 each record airborne sound from the surroundings of the hearing instrument 4. The microphones 18 convert the sound into an (input) sound I, i.e. into an electrical signal which contains information about the recorded sound. The respective input audio signal I is supplied within the hearing instrument 4 to the signal processor 20, which modifies this input audio signal I in order to support the hearing ability of the user, in particular frequency-selectively amplifies it in order to compensate for a hearing loss of the user.The signal processor 20 outputs an output audio signal O to the listener 12 via signal lines (not shown) of the electrical connecting cable 16 guided in the housing 8 and the connector 14. The output audio signal O is an electrical signal containing information about the sound processed and thus modified. The signal processor 20 and all further electrical or electronic components of the hearing instrument 4 are supplied from the battery 22 with an electrical direct voltage referred to as operating voltage U B.The wireless communication device 24 serves for (wirelessly) data exchange between the hearing instrument 4 and the hearing app 6 and / or optionally further components of the hearing system 2, e.g. a further hearing instrument 4 (not shown) for the other ear of the user.The hearing app 6 is used in particular for remote control and programming of the hearing instrument 4. In the example shown, this computer is a user's smartphone 36. The computer, in particular the smartphone 36, is not a component of the hearing system 2 itself, but is used by the hearing app 6 only as an external resource for computing power, storage space and communication services. In particular, the hearing app 6 accesses a wireless communication device (not shown in more detail) of the smartphone 36 in order to exchange data with the hearing instrument 4.The wireless communication device 24 of the hearing instrument 4 and the wireless communication device of the smartphone 36 are generally designed for exchanging radio signals (also: radio waves, namely electromagnetic radiation with a radio frequency of more than 100 MHz). Preferably, the data transmission between the hearing instrument 4 and the smartphone 36 (and thus the hearing app 6) takes place on the basis of the Bluetooth standard, at a radio frequency of 2.4 GHz.The capacitive sensor 26 serves for detecting the seating of the hearing instrument 2 on the ear of the user, that is to say for checking whether the housing 8 is located in a provided wearing position behind the ear of the user or a position deviating therefrom. A first sensor electrode 30 of the capacitive sensor 26 is formed by a one- or two-dimensional electrically conductive structure which is arranged in the housing 8, in particular lying against or close to an inner side of the housing wall. The first sensor electrode 30 is formed, for example, by a wire conductor, a wire grid or braid, a metal stamped part, a foil or an electrically conductive coating applied to the inner side of the housing wall. The second sensor electrode 32 is formed by the section of the connecting cable 16 guided in the connecting part 14, namely here either by one of the signal conductors or both signal conductors or by a separate conductor of the connecting cable 16 that may be present.In order to prevent a capacitive interaction between the sensor electrode 30 and the section of the connecting cable 16 guided in the interior of the housing 8, the section of the connecting cable 16 inside the housing is preferably electrically shielded from the sensor electrode 30 by a shield 38 (FIGS. 2 and 3 ). The electrical leads between the sensor controller 28 and the sensor electrodes 30 and 32 are also preferably electrically shielded, and the shield 38 is optionally designed as a potential-controlled shield ("driven shield").As will be explained in more detail below, the sensor controller 30 controls at least one of the sensor electrodes 30 and 32 (in the example according to FIG. 1, the connecting cable 16 used as sensor electrode 32 with an electrical alternating voltage referred to as sensor voltage Us, the alternating voltage frequency of which lies between 20 kHz and 10 MHz and is, for example, 60 kHz. The sensor voltage Us is thus in particular spectrally spaced apart between the operating voltage U B generated by the battery 22, on the one hand, and the radio frequency of the wireless communication device 24, on the other hand. It is likewise above the audible frequency spectrum, so that perceptible interference of the output audio signal O and the sound signal generated therefrom by the sensor voltage Us fed into the connecting cable 16 is excluded.The signal processor 20, the transceiver of the wireless communication device 24, and the sensor controller 28 are each optionally formed by a programmable circuit (e.g., a microprocessor) having software installed therein, by a non-programmable circuit (e.g., in the form of an ASIC), or by a combination of at least one programmable subunit and at least one non-programmable subunit. As indicated by way of example in FIG. 1, the signal processor 20, the communication device 24 and the sensor controller 28 can each be configured as separate circuits. Alternatively, the communication device 24 and / or the sensor controller 28 are integrated with the signal processor 20 and / or at least one further control unit, if present, of the hearing instrument 4 in a common circuit.In two alternative embodiment variants of the hearing instrument 4 according to FIGS. 2 and 3, the sensor electrodes 30 and 32 are controlled differently by the sensor controller 28.In the embodiment according to FIG. 2, the sensor electrodes 30 and 32 are operated by the sensor controller 28 as a transmitting electrode and a receiving electrode, respectively. The sensor controller 28 applies the sensor voltage Us to the sensor electrode 32 (i.e., the connecting cable 16). Under the effect of the sensor voltage Us, the sensor electrode 32 generates an electric field E in a surrounding spatial volume, which electric field changes with the AC voltage frequency and which causes a charge shift in the sensor electrode 30 and thus an electric current flow. The sensor controller 30 preferably measures the current intensity of this current flow at the sensor electrode 30 as a response signal A, wherein this response signal A is characteristic of the (electrical) capacitance of the capacitor formed by the sensor electrodes 30 and 32. The capacitive sensor 26 is thus designed as a "relative capacitance sensor" (Mutual Capacitance Sensor).Due to the alternating current conductivity of the human body and the electrical connection of the body to the sensor controller 28 via ground M, body structures 40 of the user, e.g. the head and the ear, on which the housing 8 and the connecting piece 14 are worn, act as interference potential, which reduces the capacitance of the capacitor formed by the sensor electrodes 34 aand 34 b, and thus the value of the measured response signal A, the more the larger the body structures are, and the closer they are arranged to the sensor electrodes 30 and 32.In the embodiment according to FIG. 3, the sensor electrodes 30 and 32 are operated by the sensor controller 28 as separate (i.e. independent of one another) sensor electrodes. Here, the sensor controller 28 applies the sensor voltage Us to both the sensor electrodes 30 and 32 and measures the response signal A generated under the effect of the sensor voltage Us independently for each of the sensor electrodes 30 and 32; also in this case, the current of the current flowing to the respective sensor electrode 30, 32 is preferably measured as the response signal A. The response signal A assigned to the respective sensor electrode 30, 32 is characteristic here of the capacitance of the respective sensor electrodes 30 and 32 with respect to ground M. The capacitive sensor 26 is therefore designed in this embodiment as a "self-capacitance sensor" (self-capacitance sensor). The two sensor electrodes 30 and 32 are preferably supplied with the sensor voltage Us in phase, so that no electric field E runs between the two sensor electrodes 30 and 32 themselves.The electric field E generated by the respective sensor electrode 30, 32 under the effect of the sensor voltage Us extends here between the respective sensor electrode 30, 32 and the respectively closest body structures 40 of the user. The body structures 40 of the user lying on ground M for alternating voltages in the vicinity of the hearing instrument 4, in particular thus the head and the adjacent ear, act in this embodiment of the capacitive sensor 26 as a counter electrode to the respective sensor electrode 30, 32. Each of the sensor electrodes 30, 32 forms, together with the closest body structures 40, the capacitor, the capacitance of which is measured at the respective sensor electrode 30, 32. This capacitance and thus the value of the measured response signal A-unlike in the embodiment according to FIG. 2-becomes higher the larger the body structures 40 are and the closer they are arranged to the respective sensor electrode 30, 32.The embodiment according to FIG. 2 has the advantage over the embodiment according to FIG. 3 that the sensor controller 28 here makes do with a single sensor input for measuring the one response signal A and can therefore be realized particularly easily.In the embodiment according to FIGS. 2 and 3, the capacitive sensor 26 detects only the seat of the housing 8 and of the connecting piece 14 directly, since the sensor electrodes 30 and 32 are arranged only in the region of these parts of the hearing instrument 4. The fit of the earpiece 10 in the user's ear is here checked only indirectly, it being assumed that the earpiece 10 is correctly positioned in the user's ear if the position of the housing 8 and of the connecting piece 14 corresponds to the intended wearing position.In a further embodiment (not shown in more detail) of the hearing instrument 4, a metallic housing of the receiver 12 is also used as a sensor electrode of the capacitive sensor 26 in addition to the connecting cable 16. The housing of the receiver 12 is preferably short-circuited here to the conductor of the connecting cable 16 used as sensor electrode 32 (in particular to shield the connecting cable 16), so that the connecting cable 16 and the receiver 12 together form the sensor electrode 32. The capacitive sensor 26 in this case also detects the (correct or incorrect) fit of the earpiece in the user's ear immediately.In an alternative embodiment, the receiver 12 (more precisely the metallic housing of the receiver 12) is operated by the sensor controller 28 as a separate sensor electrode in addition or alternatively to the connecting cable 16. With this separate sensor electrode, the seating of the earpiece in the user's ear is detected independently of the seating of the housing 8 and of the connecting piece 14 on the ear.In all of the embodiments described above, the or each measured response signal A is used during operation of the hearing instrument 4 in a method for checking the seat of the hearing instrument 4. For automatically carrying out this method, the hearing system 2 comprises a seat control unit 42 which is configured to check the seat of the housing 8 on the ear of the user on the basis of a sensor signal S output by the capacitive sensor 26, i.e. to determine whether the hearing instrument 4 (i.e. housing 8, the connecting piece 14 and optionally the earpiece 10) is located in a provided wearing position on the ear of the user or whether the seat of the housing 8, the connecting piece 14 and optionally the earpiece 10 deviates from the provided wearing position.The seat control unit 42 can be formed within the scope of the invention by a non-programmable electronic circuit, for example in the form of or as part of an ASIC. Preferably, however, the seat control unit 42 is formed by a software module which is installed in a running-capable manner, for example, in the signal processor 20 (see FIG. 1 ) or, if appropriate, in another programmable control circuit of the hearing instrument 4. In a further embodiment of the invention, the seat control unit 42 is implemented outside the hearing instrument 4 as part of the hearing app 6.The sensor signal S output by the sensor controller 28 to the seat control unit 42 contains the (unchanged) value of the or each response signal A or a variable derived therefrom, for example the capacitance assigned to the sensor electrodes 30, 32 (optionally each) or a variable inverted or scaled thereto.In order to check the seat of the hearing instrument 4 behind the ear of the user, the seat control unit 42 compares the sensor signal S in a preferred embodiment of the method with a stored reference value which reproduces the value of the sensor signal S when the hearing instrument 4 (i.e. in particular the housing 8 and the connecting piece 14) is positioned in the intended wearing position. If the seat control unit 42 establishes a significant deviation of the sensor signal S from the reference value (in particular a deviation that exceeds a predefined tolerance value, it causes a (warning) message to be output to the user, which message indicates to the user the wrong seat of the hearing instrument 4 (i.e. deviating from the intended wearing position).Since the value of the sensor signal S is also influenced by the approach of further body parts to the hearing instrument 4, e.g. the approach of a hand or a finger, but these disturbing influences are generally only of a short duration, the seat control unit 42 is preferably designed to cause the output of the warning message only if the sensor signal S deviates significantly from the reference value for longer than a predefined time interval (e.g. more than 2 min) permanently.The warning message is, for example, in the form of• a signal sound emitted via the receiver 12 into the ear of the user or emitted by the hearing app 6 via a loudspeaker of the smartphone 36,• a voice message emitted via the listener 12 into the ear of the user or emitted by the hearing app 6 via a loudspeaker of the smartphone 36,• a text message or graphic displayed by the hearing app 6 via the display of the smartphone 36,• or a tactile alarm (e.g. a vibration signal) output via the hearing instrument 4 or the smartphone 36or a combination of the above notification methods. The reference value is preferably individually learned during the adaptation of the hearing instrument 4 to the user (fitting), for example by the sensor signal S being detected and stored as a reference value after the hearing instrument 4 has been positioned by a person skilled in the art in the correctly provided wearing position behind the ear of the user.In a further developed embodiment of the invention, not only is a single reference value for the sensor signal S stored in the seat control unit 42, but a function or characteristic curve or characteristic value table which, in addition to the characteristic value characteristic for the intended wearing position, also contains characteristic values for deviating positions of the hearing instrument 4 behind the ear. The function, characteristic curve or characteristic value table is also determined, for example, when adapting the hearing instrument to the user, by the housing 8 being placed by a person skilled in the art at various positions behind the ear, and by the respective value of the sensor signal S being detected and stored together with a position indication in each position. In this embodiment, the seat control unit 42 does not merely qualitatively determine, during operation of the hearing instrument 4, whether the seat of the hearing instrument 4 matches the intended wearing position by comparing the current value of the sensor signal S with the function, characteristic curve or characteristic value table. Rather, the seat control unit 42 quantitatively determines how strongly and in which direction the seat of the hearing instrument 4 deviates from the intended wearing position.If the seat control unit 42 in the above-mentioned embodiment detects a significant deviation of the sensor signal S from the reference value determined for the intended wearing position, it causes (e.g. using one of the methods described above) the output of a warning message to the user, which warning message indicates to the user the wrong seat of the hearing instrument 4 and contains an instruction for correcting the seat.Alternatively, the seat control unit 42 adjusts at least one signal processing parameter of the hearing instrument 4 on the basis of the sensor signal S output by the capacitive sensor 26, so that an effect of the malpositioning of the housing 8 is completely or partially compensated. For example, the seat control unit 42 adjusts a beam former of the signal processor 20 of the hearing instrument 4 in such a way that a directional lobe of the beam former is aligned with respect to the user's head just as in the intended wearing position (e.g. always perpendicular to the longitudinal axis of the head) even if the housing 8 is not positioned.In a further refined embodiment of the invention, the seat control unit 42 follows a differentiated method sequence. In this case, the seat control unit 42 adjusts the at least one signal processing parameter of the hearing instrument 4 only-as described above-for compensating a detected lack of fit of the hearing instrument 4 if the detected deviation of the seat of the hearing instrument 4 from the intended wearing position is small (in particular does not exceed a stored threshold value). Otherwise, i.e. in the case of a greater malpositioning of the hearing instrument 4, the seat control unit 42 causes, as likewise described above, the output of the warning message, which indicates to the user the lack of fit of the hearing instrument 4 and contains an instruction for correcting the seat.In a further embodiment of the invention, the seat control unit 42 contains a neural network individually trained on the user, which contains the sensor signal S as an input signal and, in the event of a significant lack of fit of the hearing instrument 4, initiates at least one corrective measure, in particular (as described above) an adaptation of at least one signal processing parameter of the hearing instrument 4 for compensating the lack of fit and / or the output of a warning message to the user.In further embodiments of the invention, the hearing instrument is a classic BTE device with a housing worn behind the ear and a receiver arranged in this housing. In this case, the connecting piece 14 is formed by a sound hose. Here, for example, a wire guided in the sound tube is used as the sensor electrode 32. The above explanations for the embodiment and arrangement of the capacitive sensor and for checking the seat of the hearing instrument 4 on the ear can be easily transferred to this type of device.The invention is particularly clear from the above-described exemplary embodiments, but is in no way limited thereto. Rather, other embodiments of the invention may be derived from the claims and the foregoing description.List of reference characters2 Hearing system 4 Hearing instrument 6 Hearing app 8 Housing 10 Earpiece 12 Earpiece 14 Connecting piece 16 Connecting cable 18 Microphone 20 Signal processor 22 Battery 24 (wireless) communication device 26 (capacitive) sensor 28 Sensor controller 30 Sensor electrode 32 Sensor electrode 36 Smartphone 38 Shield 40 Body structure 42 Seat control unit A Response signal E (electric) field I (input) sensor line M Ground O (output) sensor line S Sensor signal U B Operating voltage Us Sensor voltage

Claims

Hearing instrument (4) - with a housing (8) worn behind the ear of a user in an intended wearing position, - with an earpiece (10) to be inserted into the ear canal of the ear, - with a flexible connecting piece (14) which connects the housing (8) to the earpiece (10), - with an output transducer (12) for converting an output audio signal (O) into a sound signal to be output to the user and - with a capacitive sensor (26) which comprises a control and evaluation circuit (28) and two sensor electrodes (30, 32) electrically connected thereto, wherein one of the two sensor electrodes (30) is arranged in the housing (8), and wherein the other sensor electrode (32) is arranged in the connecting piece (14) and / or the earpiece (10).Hearing instrument (4) according to Claim 1, wherein the control and evaluation circuit (28) of the capacitive sensor (26) is configured to apply an electrical alternating voltage (Us) to one of the sensor electrodes (32) and to measure a response signal (A) generated under the action of this alternating voltage (Us) on the other sensor electrode (30), which response signal is characteristic of an electrical capacitance of a capacitor formed by the sensor electrodes (30, 32).Hearing instrument (4) according to claim 1 or 2, wherein the output transducer (12) is arranged in the earpiece (10), wherein the connector (14) comprises an electrical connecting cable (16) for supplying the output audio signal (O) to the output transducer (12), and wherein the connecting cable (16) and / or the output transducer (12) is used as a sensor electrode (32) of the capacitive sensor (26).Hearing instrument (4) according to claim 1 or 2, wherein the output transducer (12) is arranged in the housing (8), wherein the connecting piece (14) is formed as a hollow sound tube for supplying the sound signal generated by the output transducer (12) to the earpiece (10), and wherein at least one of the sensor electrodes (32) of the capacitive sensor (26) is arranged in the sound tube.Hearing system (2) comprising a hearing instrument (4) according to one of Claims 1 to 4, and comprising a seat control unit (42) which is configured to check the seat of the housing (8) and of the connection piece (14) on the ear of the user on the basis of a sensor signal (S) output by the capacitive sensor (26) and to output a message indicating the deviating seat on a determination of a deviation of the seat from the intended wearing position, and / or which is configured to set at least one signal processing parameter of the hearing instrument (4) on the basis of the capacitive sensor signal (S) output by the capacitive sensor (26), in order to adapt the signal processing of the hearing instrument (4) to the determined seat.Method for operating a hearing instrument (4) according to one of Claims 1 to 4, wherein - a capacitive sensor signal (S) is determined by means of the capacitive sensor (26) as a measure for the seat of the housing (8) and of the connection piece (14) on the ear of the user, and - a message indicating the deviating seat is output when a deviation of the seat from the intended wearing position is determined, and / or - at least one signal processing parameter of the hearing instrument (4) is set on the basis of the capacitive sensor signal (S) output by the capacitive sensor (26), in order to adapt the signal processing of the hearing instrument (4) to the determined seat.

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