EP2229010A2 - Method for compensating for interference in a hearing aid, hearing aid and method for adjusting same - Google Patents

Abstract

The method involves determining a spectral band as a function of a hearing ability and/or a spectral distribution of energy of an interference sound (12). An input signal of a hearing device (8) that represents a sound in a spectral band is filtered according to a transmission function for the sound on an interference sound path. A compensation sound (15) is generated using the input signal in inverted and filtered form. Independent claims are also included for the following: (1) an hearing apparatus comprising a processing device for providing a spectral band and/or for determining a spectral band (2) a method of adjusting a hearing apparatus (3) an apparatus for adjusting a hearing apparatus.

Description

The invention relates to a method for compensating for background noise in a hearing device. The invention also relates to a hearing device which is designed to compensate for background noise. Furthermore, the invention relates to a device and a method for adjusting a hearing device. The term hearing device is understood in particular to mean a hearing device. In addition, however, the term includes other portable acoustic devices such as headsets, headphones and the like.

Hearing aids are portable hearing aids that are used to care for the hearing impaired. In order to meet the numerous individual needs, different types of hearing aids such as behind-the-ear hearing aids (BTE), hearing aid with external receiver (RIC: receiver in the canal) and in-the-ear hearing aids (IDO), e.g. Concha hearing aids or canal hearing aids (ITE - In the ear, CIC - Completely in the canal). The hearing aids listed by way of example are worn on the outer ear or in the ear canal. In addition, bone conduction hearing aids, implantable or vibrotactile hearing aids are also available on the market. The stimulation of the damaged hearing takes place either mechanically or electrically.

Hearing aids have in principle as essential components an input transducer, an amplifier and an output transducer. The input transducer is usually a sound receiver, z. As a microphone, and / or an electromagnetic receiver, for. B. an induction coil. The output transducer is usually used as an electroacoustic transducer, z. As miniature speaker, or as an electromechanical transducer, z. B. bone conduction, realized. The amplifier is standard integrated into a signal processing unit. This basic structure is in FIG. 1 shown using the example of a behind-the-ear hearing aid. In a hearing aid housing 1 for carrying behind the ear, one or more microphones 2 for receiving the sound from the environment are installed. A signal processing unit 3, which is also integrated into the hearing aid housing 1, processes signals from the microphones and amplifies the processed signals. The output signal of the signal processing unit 3 is transmitted to a loudspeaker or earpiece 4, which outputs an acoustic signal. The sound is optionally transmitted via a sound tube, which is fixed with an earmold in the ear canal, to the eardrum of the device carrier. The power supply of the hearing device and in particular the signal processing unit 3 is effected by a likewise integrated into the hearing aid housing 1 battery. 5

A sound detected by a microphone of a hearing aid also partially contains disturbing noises from an environment of the equipment wearer. These ambient sounds can be attenuated in the microphone signal by the signal processing unit of a hearing aid by means of a filter for noise reduction. The filtered microphone signal can then be converted by a receiver of the hearing device into a sound signal, which is delivered into the ear canal of the device carrier. It is important that not even a sound from the environment directly, d. H. on the acoustic path, from the environment into the ear canal to the eardrum. Such a sound, which has undesirably passed from the environment directly, for example, through a ventilation opening of an otoplastic into the auditory canal of the device carrier, is referred to as noise in the context of this invention. In the form of background noise, the ambient noise is again audible to the equipment wearer, which were elaborately filtered out in the microphone signal of the hearing aid.

From the prior art, a hearing aid for aviation is known in which an ambient sound by means of a compensation sound broadband is compensated. For this purpose, an ambient sound is superimposed with the compensation sound in the ear canal of a wearer of the hearing aid. The compensation sound is phase inverse. It compensates in the auditory canal for the pressure fluctuations that would be caused by the ambient sound without the compensatory sound. In other words, the ambient sound and the compensation sound cancel each other out by their superposition. Compensating for noise by means of a compensation sound is called active noise cancellation (ANC) or more generally active sound compensation.

In order to be able to generate a compensation sound with an earphone set, special components, in particular special transducers, must be used. Otherwise, a system formed by the converters and a compensation filter has too large a group delay. In other words, without the special components, it is not possible to provide a compensating sound having a correct phase.

In hearing devices, such as. As hearing aids, usually no specially designed to form a compensation sound components can be used. For hearing devices, the components must already be optimized for other aspects. As a result, no system with the required group delay can be formed for active noise compensation. Also, it is usually not possible, for example in an earmold of the hearing aid to strongly attenuate an ambient sound when it passes through a ventilation opening of the earmold, a so-called Vent, as a noise to a tympanic membrane of a device carrier. Damping in a vent would mean that also the vented air exchange between the equipment wearer's environment and the ear canal would be degraded.

It is an object of the present invention for a device carrier to reduce the perceptibility of noise, which penetrates to his ear on a direct, so acoustic way. It is another object of the invention to provide a corresponding hearing device.

The invention is achieved by a method according to claim 1. Furthermore, the object is achieved by a method according to claim 11. The object concerning the hearing device is achieved by a hearing device according to claim 5 and a device according to claim 14.

• Bestimmen eines spektralen Bands in Abhängigkeit von einem Hörvermögen und/oder einer spektralen Verteilung der Energie des Störschalls oder eines den Störschall hervorrufenden Schalls,
• Filtern eines den Schall repräsentierenden Eingangssignals der Hörvorrichtung in dem spektralen Band entsprechend einer Übertragungsfunktion für den Schall auf einem Störschallpfad und
• Erzeugen eines Kompensationsschalls mit Hilfe des invertierten gefilterten Eingangssignals.

According to the invention, a method is provided for compensating an interference sound in a hearing device. This method comprises the steps:

• Determining a spectral band as a function of a hearing and / or a spectral distribution of the energy of the noise or a sound causing the noise,
• Filtering a sound representing input signal of the hearing in the spectral band corresponding to a transfer function for the sound on a Störschallpfad and
• Generating a compensation sound using the inverted filtered input signal.

The hearing includes a subjective loudness perception by a device wearer. Such a perception of loudness can be determined by methods of psychoacoustics known per se. However, the hearing can also be an auditory threshold, as it is e.g. can be determined by a hearing curve.

With the method, a compensation sound for a hearing device can be generated. Compensation does not take place for all frequencies, but only for frequencies in that spectral band in which a device carrier, for example hears particularly well according to his hearing and / or in which, for example, a sound has a lot of sound energy. Such a spectral band can often be relatively narrow in relation to the total range of audible frequencies. The method may also be designed for compensating in multiple spectral bands.

The compensation sound can also be generated in particular without specially optimized device components. In fact, during filtering, an unfavorable group delay caused, for example, by the transducers of the hearing device may be corrected by a group delay of the filter which is negative in the particular spectral band. Such a correction is impossible with a broadband active sound compensation.

By the term Störschallpfad the entirety of all acoustic transmission paths is meant over which, for example, an ambient sound, or a significant proportion of the same, from an environment of a device carrier can reach his eardrum, where he then perceptible as noise in the context of the invention. The interference sound path does not include the transmission that is intended to be effected by the hearing device in a partially electronic way.

When unwanted penetration of ambient sound to the eardrum, the ambient sound is changed spectrally. This spectral change is described by a transfer function of the Störschallpfads. A transfer function of a Störschallpfads can be determined, for example, by a manufacturer by measurements using methods known per se from the prior art.

By filtering the input signal with a transfer function corresponding in some spectral band to the transfer function of the noise path, the filtered input signal for the spectral band has the same spectral characteristics as the noise.

Of course, within the scope of the invention, a further filtering of the input signal can be provided by which, for example, a transmission behavior of a microphone or a loudspeaker of the hearing device is compensated.

By inverting the filtered input signal during the filtering or subsequently, a signal results, from which a sound inverse to the phase of the noise, that is to say a compensation sound, can be generated. The compensation property is ensured by the inventive method, in particular in the particular spectral band.

If in the method the spectral band is determined as a function of the spectral distribution of the energy of the noise or the noise causing the noise, an advantageous development results if the determination of the spectral bands is repeated periodically or continuously. By constantly adapting the spectral band to the spectral distribution of the energy of the sound to be compensated, it is possible to compensate for it even when an ambient noise changes rapidly in its spectral composition.

A further advantage results if, for filtering as a function of the spectral band, one of a plurality of predetermined filters is selected or a filter is calculated. By a filter is meant here all those parameters which are necessary for the configuration of a filter algorithm. These parameters of a filter algorithm are also called coefficients of a filter.

By providing a plurality of already calculated filters for different spectral bands in which a compensation by means of the compensation sound is to be made possible, the outlay for calculating a compensation sound signal is particularly low. Calculating a filter as a function of a spectral band allows to provide a filter for any spectral band.

An advantageous development of the method results if the filter multiplies the transfer function by a predetermined factor that describes an influence on the transfer function in the particular spectral band that the hearing device interacts with an ear of a user. By means of the multiplicative factor, it is possible to adapt the inventive method with a very low cost for a particular user of the hearing.

• einer Verarbeitungseinrichtung zum Bereitstellen eines spektralen Bands in Abhängigkeit von einem Hörvermögen und/oder zum Bestimmen eines spektralen Bands in Abhängigkeit von einer spektralen Verteilung der Energie eines Schalls,
• einer Filtereinrichtung zum Filtern eines den Schall repräsentierenden Eingangssignals der Hörvorrichtung in dem spektralen Band entsprechend einer Übertragungsfunktion für den Schall auf einem Störschallpfad und
• einer Schallausgabeeinrichtung zum Erzeugen eines Kompensationsschalls mit Hilfe des invertierten gefilterten Eingangssignals.

The invention also includes a hearing device

• a processing device for providing a spectral band as a function of a hearing and / or for determining a spectral band as a function of a spectral distribution of the energy of a sound,
• a filter device for filtering a sound-representing input signal of the hearing device in the spectral band corresponding to a transfer function for the sound on a noise path and
• a sound output device for generating a compensation sound using the inverted filtered input signal.

With such a hearing device, it is possible to compensate for a sound in a particular spectral band, without thereby affecting other functionalities of the hearing device, such as e.g. Noise reduction or ventilation through a vent.

In the event that a spectral distribution of the energy of the sound can be determined with the processing device of the hearing device, an advantageous development results if the processing device comprises a filter bank. With a filter bank, the spectral distribution of the sound energy is always at intervals of a few milliseconds redeterminable again. Consequently, that spectral band can be determined correspondingly fast, for which a compensation sound signal is to be calculated by the filter device.

The hearing device is advantageously further developed in that the filter device comprises a recursive, linear filtering. By using a linear filter, there is the advantage that little computing time is needed to calculate a compensation sound signal. A recursive filter has the advantage that particularly few coefficients are required for simulating a transfer function for the sound on an interference sound path, so that the calculation can be carried out with particularly few calculation steps. With a recursive filter also a very low group delay can be achieved.

Furthermore, it is advantageous if the filter device of the hearing device comprises an adaptive filter. This makes it possible to use one and the same filter for different spectral bands. The filter only has to be adapted to the transfer function of the noise path before filtering in the corresponding spectral band.

As an alternative to an adaptive filter, it is also advantageous if a plurality of filters are provided in the filter device, from which filter one of them can be selected depending on the particular spectral band. By calculating the filters, i. that is, the parameter or coefficient, in advance, it is possible to calculate the compensation sound signal very quickly.

In the hearing device, the transfer function is advantageously formed from a spectral profile and a scaling factor. The spectral curve describes the ratio of the influence of the Störschallpfads on the sound in one frequency to the influence of the Störschallpfads on the sound in another frequency. In other words is operated by the spectral curve only the principal form of the transfer function. The spectral course and the transfer function can still differ by a multiplicative factor. This multiplicative factor is the scaling factor.

The division results in the advantage that the hearing device can be adapted particularly easily to a user. Namely, while the spectral course can be determined by measurements in the production of the hearing device, the spectral profile with an actual transfer function, as it results when wearing the hearing device, can easily be brought into coincidence by adapting the hearing device for a user only the scaling factor has to be determined.

• Bestimmen eines Hörvermögens,
• Auswählen oder Ermitteln eines Kompensationsfilters zur Kompensation von Störschall in Abhängigkeit von dem Hörvermögen und
• Konfigurieren eines Filters der Hörvorrichtung gemäß dem ausgewählten oder ermittelten Kompensationsfilter.

The invention also includes a method for adapting a hearing device with the steps:

• Determining a hearing,
• Selecting or determining a compensation filter to compensate for background noise as a function of the hearing and
• Configure a filter of the hearing device according to the selected or determined compensation filter.

The compensation filter is preferably chosen so that in the spectral band for which the user has a good hearing, a compensation sound can be provided by means of the compensation filter. Good hearing, as already mentioned, is to be understood in particular as a pronounced loudness sensation. The compensation can also be done for several spectral bands. A configuration can be done, for example, by storing parameters or coefficients of the compensation filter in the hearing device so that a filter unit of the hearing device can filter the input signal accordingly.

The method is advantageously extended by the fact that determining the compensation filter comprises calculating coefficients as a function of the hearing and of a transfer function for a sound on a noise path. As a result, the hearing device can be individually adapted to a user in terms of compensating for background noise.

In the method, there is a further advantage if the configuring includes transmitting the selected and determined compensation filter to the hearing device. The selection or determination thus takes place outside the actual hearing device. This does not rely on the storage capacity and computing capacity of the hearing device when it comes to selecting or determining a compensation filter. A list of possible compensation filters for selection and a comprehensive algorithm for calculating a compensation filter can be provided by dedicated devices. It is only necessary to transfer the finished compensation filter to the hearing device.

• einer Messeinrichtung zum Bestimmen eines Hörvermögens,
• einer Ermittlungseinrichtung zum Auswählen oder Ermitteln eines Kompensationsfilters zur Kompensation von Störschall in Abhängigkeit von dem Hörvermögen und
• einer Einstelleinrichtung zum Konfigurieren eines Filters der Hörvorrichtung gemäß dem ausgewählten oder ermittelten Kompensationsfilter.

The invention also includes a device for adapting a hearing device

• a measuring device for determining a hearing,
• a determination device for selecting or determining a compensation filter for compensation of background noise as a function of the hearing and
• an adjusting device for configuring a filter of the hearing device according to the selected or determined compensation filter.

With this device, the method for adjusting a hearing device can be easily implemented.

The device is developed in an advantageous manner by storing in the determination device a plurality of predetermined compensation filters, one of which can be selected as a function of the hearing. As a result, the device is also operable for persons who are not familiar with a calculation of compensation filters.

FIG 1

eine schematische Darstellung einer Hörvorrichtung aus dem Stand der Technik mit darin enthaltenen Komponenten,

FIG 2

eine Darstellung eines Gehörgangs mit einem darin befindlichen In-dem-Ohr-Hörgerät gemäß einer Ausführungsform einer erfindungsgemäßen Hörvorrichtung,

FIG 3

einen Signalflussgraphen für ein Schallsignal, wie er sich bei einer Ausführungsform eines erfindungsgemäßen Verfahrens zum Kompensieren eines Störschalls ergibt,

FIG 4

einen Schaltplan eines Hörgeräts gemäß einer Ausführungsform einer erfindungsgemäßen Hörvorrichtung,

FIG 5

einen Schaltplan eines Programmiergeräts für ein Hörgerät gemäß einer Ausführungsform einer erfindungsgemäßen Vorrichtung zum Anpassen einer Hörvorrichtung und

FIG 6

eine Zusammenstellung von Diagrammen mit Graphen von mehreren spektralen Größen, wie sie sich bei einer Ausführungsform eines erfindungsgemäßen Verfahrens zum Kompensieren eines Störschalls ergeben.

The invention will be explained in more detail below with reference to examples. To show:

FIG. 1

a schematic representation of a hearing device of the prior art with components contained therein,

FIG. 2

1 a representation of an auditory canal with an in-the-ear hearing device located therein according to an embodiment of a hearing device according to the invention,

FIG. 3

a signal flow graph for a sound signal, as it results in an embodiment of a method according to the invention for compensating for noise,

FIG. 4

a circuit diagram of a hearing aid according to an embodiment of a hearing device according to the invention,

FIG. 5

a circuit diagram of a programming device for a hearing aid according to one embodiment of a device according to the invention for adjusting a hearing and

FIG. 6

a compilation of graphs with graphs of several spectral magnitudes, as they result in one embodiment of a method according to the invention for compensating for noise.

The illustrated examples represent preferred embodiments of the invention.

In FIG. 2 an ear with an auricle 6 and an ear canal 7 is shown. In the ear canal 7, a hearing aid 8 is introduced. In the hearing device 8, a vent 9 is formed through which fresh air from an environment of the ear can flow into the ear canal 7. Such ventilation significantly increases the wearing comfort for the user of the hearing device 8.

In the environment is also a sound source 10, which emits an unwanted sound 11, so a sound to the auricle 6 down. The sound 11 can penetrate through the vent 9 in the ear canal, where it can meet as a noise 12 on a tympanic membrane 13 of the user. The sound 11 thus reaches the eardrum 13 in a purely acoustic way through the vent 9.

The in FIG. 2 shown Störschall 12 represented in the example also further noise that penetrates another way from the environment of the device carrier to the eardrum.

The background noise 12 is so far attenuated in a region 14 in front of the eardrum 13 by compensation by means of a compensation sound 15 that it is barely audible to the user of the hearing aid 8. The compensation sound 15 is superimposed on the background noise 12 in such a way that the sound formed by the superimposition of this sound has significantly less energy in the region 14 than the background noise 12 alone does. The sound formed from the two superimposed sound has in the area 14 but not across all frequencies significantly less energy than the noise 12 alone. The compensation is only effected for those frequencies which can be perceived relatively well by the user of the hearing device 8 and in which, on the other hand, the background noise 12 has a relatively large amount of energy. The totality of these frequencies forms a spectral band.

The compensation sound 15 is part of a sound that a listener 16 of the hearing device 8 radiates. The listener 16 emits the compensation sound 15, because a useful signal which converts the listener 16 into sound, a compensation sound signal is additively superimposed. The compensation sound signal is calculated from a microphone signal that a microphone 17 of the hearing device 8 generates. The microphone signal is an input signal in the sense of the invention and represents the sound 11 from the environment of the user.

In order to calculate the compensation sound signal from the microphone signal, the microphone signal is filtered by means of a filter 18 of the hearing device 8 in such a way that it has the same spectral properties as the noise 12 in the mentioned spectral band. From the filtered microphone signal then the compensation sound signal is generated, in which the filtered signal is inverted. For a plot of a filtered microphone signal graph, this means that its sign is reversed for each digit of the graph. For a spectrum of the filtered microphone signal this means that for each frequency of the spectrum the phase is changed by 180 °. The inverting is done in the example by an inverter 19. The filter 18 and the inverter 19 act together as a compensation filter according to the invention.

The filter 18 and the inverter 19 can also be combined to form a compensation filter. The filter function of the filter 18 is then such that filtering and inverting are performed together. A separate inverter is then not necessary.

The filter 18 is a recursive, linear filter. This makes it possible to provide a required group delay of the filter in a particular spectral band. The filter 18 forms the spectral change of the sound 11 as it passes through the vent 9 and through the remaining locations en route to the ear canal 7 only for that mentioned spectral Band exactly after. In this case, it is also taken into account that a microphone signal to be processed by the filter 18, since it is actually intended to represent the sound 11, has been falsified by a transmission characteristic of the microphone 17. In addition, it is considered that the receiver 16 also causes distortion when converting the compensation sound signal into the compensation sound 15. The filter 18 compensates for this influence of the two transducers and other components of the hearing aid.

The function of in FIG. 2 The hearing aid 8 is for the user not only a hearing aid, but it also acts like an active earplugs, ie it compensates for the noise 12, which reaches the eardrum 13 of the user, for example by the vent 9. For this purpose, the ambient sound 11 is recorded with the aid of the microphone 17 of the hearing device 8 and the spectral characteristic of the microphone signal is modified by means of the filter 18 and the inverter 19. From the filtered and inverted microphone signal (compensation sound signal) the compensation sound is then generated by means of the receiver 16. The superimposition of the sound 11, which unintentionally reaches the eardrum 13 as noise 12, with the compensation sound 15, which the hearing aid 8 emits, leads to the desired extinction of the noise in the area 14 directly on the eardrum 13 of the user.

With the hearing aid 8 it is not possible to dimension the filter 18 so that it functions ideally for the entire audio frequency range. This is because a hearing aid is not built exclusively for the purpose of active noise cancellation. Therefore, the components of the hearing aid 8 used, that is, for example, the microphone, the earpiece, the housing shape and damping materials, are not such that an active noise compensation can be ideally achieved. Therefore, the active noise compensation in the hearing aid 8 is limited to a specific spectral band.

By suitable dimensioning of the filter 18, it can be controlled in which frequency band an active noise compensation is particularly effective and in which frequency band or in which frequency bands the active noise compensation behaves suboptimally. The consequence is that the active noise compensation decreases in certain frequency ranges or even instead of a sound cancellation in certain frequency bands a sound amplification takes place.

In combination with the knowledge of a user's hearing loss, the frequency band in which the active noise compensation works particularly well can be placed in that frequency band in which the wearer of the hearing device perceives a background noise relatively clearly or loudly. Conversely, the artifacts that arise in frequency ranges with poor noise compensation, masked by the hearing loss of the hearing aid wearer.

In FIG. 3 is in connection with FIG. 2 illustrates once again how the signal of the sound 11 of the sound source 10 on an interference sound path 20a and on a signal path 20b to the area 14 in the ear canal of the user passes. The Störschallpfad 20a represents the unwanted transmission of the sound 11 through the vent and along the remaining paths from the environment into the interior of the ear canal. About the Störschallpfad 20a of the sound 11 passes as noise to the area 14. When passing through the vent and during the transmission along the remaining paths of the sound 11 is changed in its spectral properties. This will be in FIG. 3 symbolized by a transfer function H of the Störschallpfads 20a.

The signal path 20b represents the path of the signal of the sound 11, as determined by the electronic processing of the sound 11 in the sound in FIG. 2 shown hearing aid is formed. The signal path 20b comprises the conversion of the sound 11 into a microphone signal, the filtering of the microphone signal by means of the in FIG. 2 illustrated filter 18 and the inverter 19 and the generation of the also in FIG. 2 The compensation filter 15 shown on the handset 16. The filter modifies the microphone signal according to a transfer function H 'of the filter 18th

By means of the transfer function H ', it is possible for the particular spectral band to produce in the region 14 a sound having approximately the same spectral properties as the sound transmitted via the noise path 20a. The agreement is so great that only barely audible artifacts arise in the spectral band in a compensation. At best, the match is perfect, so the artifacts do not arise.

It is achieved by the inverter 19 that the signal filtered by the filter 18 in accordance with the transfer function H 'in the spectral band acquires the properties of a compensation sound signal. The output signal of the inverter 19 is then by means of the in FIG. 2 shown receiver 16 converted into a compensation sound 15 and also emitted in the direction of the area 14. In the region 14, the signals of the interference sound paths 20a and the signal path 20b cancel each other out in the described manner in the spectral band.

This in FIG. 4 shown circuit diagram of an active noise compensation in a hearing aid shows how from an input signal obtained by means of a microphone 21, a compensation sound signal can be generated, which is then convertible with a listener 22 in a compensation sound.

The microphone signal of the microphone 21 is to spectrally analyzed with a filter bank 23. In FIG. 4 Individual bandpass filters 24a, 24b, 24c of the filter bank are shown. The filter bank 23 has more than the three bandpass filters 24a, 24b, 24c shown. The sake of clarity not shown Bandpass filters are symbolized by ellipsis.

The signals at the outputs of the bandpass filters 24a, 24b, 24c of the filter bank 23 are compared by a power meter 25 with each other. An output signal of a bandpass filter 24a, 24b, 24c shows how much energy is present in a spectral band for which the corresponding bandpass filter 24a, 24b, 24c is transparent. The power meter 25 determines based on the output signals of the band-pass filter 24a, 24b, 24c that spectral band in which a device carrier would perceive a background noise most clearly. It is also possible to combine several spectral bands.

For the determination of the spectral band, the power meter 25 does not directly use the distribution of the energy as can be read off at the outputs of the filter bank 23. Instead, a spectral distribution of the energy of the noise is calculated. For this purpose, the spectral distribution of the energy of the microphone signal calculated by the filter bank 23 is first weighted with a magnitude spectrum of a transfer function for the interference sound path.

The power meter 25 may also be capable of weighting the information received from the bandpass filters 24a, 24b, 24c with a user's listening curve to account for the user's subjective loudness perception for the individual spectral bands detected by the bandpass filters 24a , 24b, 24c. This may result in a spectral band in which relatively high spectral energy of the noise is still not selected by the power meter 25 because the user of the hearing aid in this spectral band has poor hearing. It may also be provided to estimate the subjective loudness perception further by means of a psychoacoustic model.

Information about the selected spectral bands is passed from the power meter 25 to a selection unit 26. The selection unit 26 configures a filter unit 27 such that the microphone signal of the microphone 21, after being filtered by the filter unit 27, forms a compensation sound signal for the spectral band selected by the power meter 25. In FIG. 4 the configuration is symbolized in such a way that the selection unit 26 acts on a selection switch 28. The selection switch 28 can be used to switch symbolically between the outputs of different filters 29a to 29d. As in the case of the filter bank 23, not all filters 29a to 29d present in the filter unit 27 are also in FIG. 4 shown. The filters, not shown, are again indicated by ellipsis. In the in FIG. 4 shown switching state of the selection switch 28, the filter 29a is active.

As already mentioned, the in FIG. 4 illustrated form of selection by means of the selector switch 28 only a symbolic representation of the process. In the hearing aid, a change between the various filters 29a to 29d is actually made possible by a filter algorithm of the filter unit 27 being configured via coefficients. In order for the filter unit 27 to filter the microphone signal according to one of the filters 29a to 29d, a corresponding set of coefficients must be passed to the filter algorithm. The various sets of coefficients representing filters 29a-29d are stored in a table. From this, the selection unit 26 makes a selection. As already described, this selection is dependent on the determined spectral band or spectral bands and thus, in the context of the invention, on the spectral distribution of the energy of the microphone signal and optionally also on the auditory ability of the user.

In the case of the filter unit 27, by restricting it to a comparatively narrow spectral band for the compensation, it is possible for this band to have a correct transit time Processing the sound to reach through the hearing aid. It is accepted that in other frequency ranges, ie outside the spectral bands determined by the arithmetic unit 25, the compensation works suboptimal. However, this is not perceived by the user.

The microphone signal is analyzed spectrally by the filter bank 23 continuously. For the respective spectral distribution of the energy of the noise, an optimal filter 29a to 29d is selected. Switching between sets of coefficients can be done as a fade to avoid switching artifacts. Instead of a table with sets of coefficients, the filter unit 27 as a filter algorithm may also contain as a whole or in part an adaptive filter.

At the in FIG. 5 schematically illustrated programming device 30, a hearing loss of a wearer of a hearing aid 32 is measured by means of an audiometer 31. The hearing loss is determined frequency dependent. The hearing of the device wearer determined by means of the audiometer 31 is detected by an operating device 33 by an acoustician on an in FIG. 5 not shown screen displayed as a hearing curve.

The operating device also stores filters 34a to 34c developed by the manufacturer of the hearing device 32. The filters are compensation filters in the sense of the invention, with which in different spectral bands for the hearing aid 32, a noise can be compensated, the 32 when wearing the hearing aid by a in FIG. 5 not shown earmold of the hearing aid 32 can penetrate to the eardrum of the wearer.

For the purposes of the invention, the filters can also be calculated in such a way that they bring about active noise compensation for typical, previously determined hearing losses. For such typical hearing losses, it is possible to determine in advance spectral bands for which compensation is required. To select a filter, the hearing curve measured with the audiometer 31 can then be compared with the typical hearing curves become. The filter is chosen to be the typical hearing curve that has the greatest similarity to the measured hearing curve.

Also in FIG. 5 symbolize omission symbols that there are other filters in addition to the filters shown 34a to 34c. The filters are stored as sets of coefficients that can be fed to a corresponding filtering algorithm. Also in FIG. 5 is accordingly too FIG. 4 symbolizing the selection of a set of coefficients from a list by acting on a selection switch 35. In FIG. 5 is selected by the selection switch 35 just the filter 34a.

The set of coefficients to the selected filter is transmitted to the hearing aid 32 by means of a dubbing device 36. In the hearing aid 32, the set of coefficients is then stored. In the in FIG. 5 As shown, it is the filter 34a that is dubbed.

It can also be provided to store all the coefficient sets of the filters 34a to 34c in the hearing device 32 itself and to transmit by means of the operating device 33 only the information about it to the hearing aid 32 as to which filter 34a to 34c is actually to be used.

When designing the filters 34a to 34c, it could not be considered to what extent the special auditory canal of the wearer of the hearing device 32, in cooperation with the earmold of the hearing device 32, has a further influence when transmitting ambient sound into the auditory canal. It can therefore be provided that the transfer functions of the filters 34a to 34c describe only a principal spectral profile. In a final step of adapting the hearing device 32 to the device carrier, a scaling factor is then determined with the aid of test signals, which is stored in the hearing device. This scaling factor is multiplicatively applied to a filtered signal so that the filtered and scaled signal actually causes active noise cancellation.

It can also be provided to use a hearing curve determined by means of the audiometer 31 to design a compensation filter individually for a hearing curve of a device carrier. This can be done by the acoustician operating the appropriate programmer. But it can also be provided to transmit the determined hearing curve, for example, to a laboratory for hearing aids. A function of the transmitted hearing curve and a transfer function, which describes the transmission behavior of a Störschallpfads a particular model of hearing aid, then a set of coefficients can be calculated, which is transmitted to the acoustician again, so that it transmits the set of coefficients in the hearing aid ,

In the FIG. 6 Diagrams D1 to D5 shown show graphs of different sizes as a function of a frequency f. The frequency range shown is an audio frequency range. Here frequencies between 0 Hz and about 15000 Hz are shown. In the FIG. 6 horizontally extending frequency axes of the individual diagrams D1 to D5 are not divided linearly, so that the explained below properties of the individual graphs are easier to represent. However, all diagrams D1 to D5 have the same non-linear distribution.

In the diagram D1, a hearing curve 37 of a wearer of a hearing aid is shown, wherein in the hearing aid the method is carried out, to which the in FIG. 6 Diagrams D1 to D5 are included. A comparison with a hearing curve 38 of a normal hearing person shows that the wearer of the hearing device 37 has a poorer hearing ability than a healthy person for all frequencies shown. In particular, there is a spectral band 39 in which the hearing aid wearer hears particularly badly. In addition, there is a spectral band 40 in which the wearer of the hearing aid can hear comparatively well.

In the diagram D2, a spectral distribution 41 of the energy of a sound over the frequency is shown. The sound comes from an environment of the wearer of the hearing aid and is z.T. accidentally transmitted acoustically, for example by a Vent of the hearing aid as noise to the eardrum of the wearer of the hearing aid. In the distribution 41, there is a spectral band 42 in which the energy of the sound is particularly large.

In the diagram D3, the subjective perception 43 of individual frequencies of the sound has been calculated by the wearer of the hearing device. The subjective perception 43 results from a weighting of the distribution 41 of the energy of the sound with the hearing curve 37 of the wearer of the hearing aid. It can be seen from the subjective perception curve 43 that a spectral band 44, for which the wearer of the hearing device perceives the sound particularly clearly, lies between the region 42 in which the energy of the sound is concentrated and the region 40, in which the wearer of the hearing aid can hear relatively well.

According to the subjective perception 43, a set of coefficients of a compensation filter is determined in the hearing aid, with which a compensation sound signal can be generated from a microphone signal which represents the sound with the energy distribution 41. The compensation filter is chosen so that the compensation is effected in particular for the area 44. However, it can also be provided to determine the compensation filter only as a function of the hearing curve 37 or only as a function of the distribution 41 of the energy of the sound. Of course, if the compensation filter is only determined as a function of a hearing curve, then the compensation filter only has to be determined once, for example when adjusting the hearing aid.

In the hearing aid several sets of coefficients are available, each with a compensation in different can cause spectral bands. In the diagram D4, those frequency ranges, ie those spectral bands 45a to 45e, are entered for the individual sets of coefficients, for each of which a set of coefficients is stored in the hearing aid. The spectral bands. which belong to further sets of coefficients are not entered in the diagram in order to keep the diagram clear. In diagram D4 this is indicated by dots.

Depending on the area 44 in which the sound from the wearer of the hearing aid is particularly well perceived, a set of coefficients, ie a compensation filter, is now selected. In the in FIG. 6 In the case shown, the spectral band compensation filter 45b is selected. In FIG. 6 For example, the boundaries of the spectral band 45b in both the diagram D3 and the diagram D5 are indicated by dashed lines.

Diagram D5 shows a transfer function 46 of the filter associated with the set of coefficients for the spectral band 45b. Furthermore, in the diagram D5, a transfer function 47 of a Störschallpfads shown, via which the sound arrives acoustically from the environment of the wearer of the hearing aid as noise to his eardrum. As can be seen from a comparison of the two transfer functions 46 and 47, the two transfer functions in the region of the spectral band 45b almost coincide. This makes it possible to generate in the spectral band 45b, with a filter unit that uses the corresponding set of coefficients, a compensation sound signal from a microphone signal representing the sound.

It can also be seen in the diagram 5 that the boundaries of a spectral band, here the spectral band 45b, need not be sharp. The limits are a transition region in which a deviation of the transfer function 46 of the compensation filter from the transfer function 47 of the Störschallpfads gradually becomes larger. In order to obtain sharp boundaries, for example, a threshold value for the deviation can be determined, which can be determined, for example, as a function of the perceptibility or measurability of artifacts in active sound compensation.

Although for the frequencies outside the spectral band 45b, the two transfer functions 46, 47 do not match, the wearer of the hearing aid still hears no noise in these frequencies. It can be seen from the subjective perception graph 43 that it does not perceive poorly compensated or even amplified noise in the frequencies outside the spectral band 45b.

The examples show how the invention makes it possible to compensate for background noise, even if the hearing device is not designed for such compensation. For calculating a compensation sound signal very little computing capacity is required.

LIST OF REFERENCE NUMBERS

1

hearing aid housing

2

microphone

3

Signal processing unit

4

receiver

5

battery

6

auricle

7

ear canal

8th

hearing Aid

9

Vent

10

sound source

11

sound

12

background noise

13

eardrum

14

Area

15

compensation sound

16

receiver

17

microphone

18

filter

19

inverter

20a

Störschallpfad

20b

signal path

21

microphone

22

receiver

23

filter bank

24a, 24b, 24c

Bandpass filter

25

power meter

26

selector

27

filter unit

28

selector switch

29a, 29b, 29c, 29d

filter

30

Programming device

31

audiometer

32

hearing Aid

33

control unit

34a, 34b, 34c

filter

35

selector switch

36

Dubbing device

37, 38

hearing curve

39, 40

spectral band

41

spectral distribution of energy

42

spectral band

43

Graph of subjective hearing

44, 45a to 45e

spectral band

46, 47

transfer function

f

frequency

D1, D2, D3, D4, D5

diagram

H, H '

transfer function

Claims (15)

A method for compensating for noise (12) in a hearing device (8,32) by Determining a spectral band (45b) as a function of a hearing (37) and / or a spectral distribution (41) of the energy of the background noise (12) or of a sound (11) causing the noise (12), - Filtering a sound (11) representing the input signal of the hearing device (8,32) in the spectral band (45b) corresponding to a transfer function (47, H) for the sound (11) on a Störschallpfad (20a) and - Generating a compensation sound (15) by means of the inverted filtered input signal. Method according to claim 1,
characterized in that
the spectral band (45b) is determined as a function of the spectral distribution (41) of the energy of the noise (12) or of the sound (11) causing the noise (12), and
the determination is repeated periodically or continuously. Method according to claim 1 or 2,
characterized in that
for filtering in dependence on the spectral band (45b) a filter (29a, 34a) is selected from a plurality of predetermined filters (29a-29d, 34a-34c) or - a filter is calculated. Method according to one of the preceding claims,
characterized in that
in filtering, the transfer function is multiplied by a predetermined factor that describes an influence on the transfer function (H) in the particular spectral band (45b) that an interaction of the hearing device (8, 32) with an ear (6, 7) of a user Has. Hearing device (8, 32) with - Processing means (23,25,26) for providing a spectral band (45b) in response to a hearing (37) and / or for determining a spectral band (45b) in response to a spectral distribution (41) of the energy of a noise (12) or a sound (11) causing the background noise (12), - Filter means (18,27) for filtering an acoustic signal (8) representing the input device of the hearing device (8,32) in the spectral band (45b) corresponding to a transfer function (47) for the sound (11) on a Störschallpfad (20a) and - A sound output device (16,22) for generating a compensation sound (15) by means of the inverted filtered input signal. Hearing device (8,32) according to claim 5,
characterized in that
a spectral distribution (41) of the energy of the background noise (12) or of the sound (11) causing the interference sound (12) can be determined with the processing device (23, 25, 26) and the processing device (23, 25, 26) has a filter bank (23). 23). Hearing device (8,32) according to claim 5 or 6,
characterized in that
the filter means (18, 27) comprises a recursive, linear filter. Hearing device (8,32) according to one of claims 5 to 7,
characterized in that
the filter means comprises an adaptive filter. Hearing device (8,32) according to one of claims 5 to 7,
characterized in that
in the filter device (8, 27) a plurality of filters (29a-29d, 34a-34c) is provided, from which for filtering one (29a, 34a) is selectable depending on the particular spectral band (45b). Hearing apparatus according to one of claims 5 to 9,
characterized in that
the transfer function is formed from a spectral curve and a scaling factor. A method for adjusting a hearing device (32) Determining a hearing (37), - Selecting or determining a compensation filter (34a) for compensation of background noise as a function of the hearing (37) and - Configuring a filter of the hearing device (32) according to the selected or determined compensation filter (34a). Method according to claim 11
characterized in that
the determining comprises calculating a compensation filter as a function of the hearing and of a transfer function for a sound on a noise path. Method according to claim 11 or 12
characterized in that
the configuring comprises transmitting the selected or determined compensation filter (34a) to the hearing device (32). Device (30) for adapting a hearing device (32) with a measuring device (31) for determining a hearing (37), - A determination device (33,35) for selecting or determining a compensation filter (34a-34c) for the compensation of background noise (12) in dependence on the hearing (37) and - An adjusting device (36) for configuring a filter of the hearing device (32) according to the selected or determined compensation filter (34a). Device (30) according to claim 14
characterized in that
in the determination device (33) a plurality of predetermined compensation filters (34a-34c) is stored, of which one (34a) is selectable in dependence on the hearing (37).

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