EP4135345A2 - Method for adjusting a digital hearing aid, hearing aid and computer program product - Google Patents

Abstract

The invention relates to a method for adjusting a digital hearing aid (2), which has an input converter (4), a signal processing device (6) and an output converter (8), the signal processing device (6) being set up to form an evaluation unit (18), a comparator unit (20) and a preamplification unit (22), with an acoustic test signal being generated by means of an external test device (34) while the hearing aid (2) is being worn by a hearing aid wearer (38), with the input converter (4) depending on of the acoustic test signal, a digital test input signal is generated, a sound pressure-dependent test variable being determined by means of the evaluation unit (18) based on the digital test input signal, with a deviation between the sound pressure-dependent test variable and a reference variable being determined by means of the comparator unit (20), which in the signal processing device ( 6) is stored, and a pre-amplification is adjusted by the pre-amplification unit (22) as a function of the deviation determined.

Description

The invention relates to a method for adjusting a digital hearing aid, which has an input converter, a signal processing device and an output converter. The invention also relates to a hearing aid and a computer program product.

Hearing aids are typically used to describe classic hearing aids with which hearing deficits can be compensated. Hearing aids of this type are used to provide hearing-impaired people, ie people with a functional deficit in their hearing organ.

With a corresponding functional deficit of the hearing organ, the hearing threshold is usually changed in at least one frequency range or frequency band such that the affected person with hearing loss only perceives acoustic signals in the corresponding frequency range at a higher or increased sound pressure level. To compensate or at least partially compensate for such a hearing deficit with a hearing aid, the sound pressure levels are expediently adjusted or changed such that an input-side level range at the input of the hearing aid is mapped onto an output-side level range at the output of the hearing aid.

Digital hearing aids, such as those used in the DE 10 2016 221 692 B3 and the DE 101 31 964 A1 are described.

Digital hearing aids usually have an input converter, a signal processing device and an output converter as essential components. In this case, part of the input converter is expediently an acousto-electric converter, ie in particular a microphone, and an analog-to-digital converter. The output converter, in turn, typically has a digital-to-analog converter and either an electromechanical converter, for example a bone conduction phone, or an electro-acoustic converter, for example a miniature loudspeaker, which is also referred to as a "phone".

The above-described mapping of the level range on the input side to the level range on the output side is then expediently carried out by a previously mentioned signal processing device, which is generally implemented by an electronic circuit implemented on a printed circuit board. Such a signal processing device for converting a corresponding image is typically set up in such a way that digital input signals are processed by the analog-to-digital converter using a number of data processing modules and digital output signals are thereby generated for the digital-to-analog converter. The data processing modules are usually programmable data processing modules, ie in particular software programs or software program modules.

The imaging is also preferably carried out in such a way that the corresponding hearing device shows a compressive behavior. If the sound pressure level at the output of the hearing aid is plotted as a function of the sound pressure level at the output of the hearing aid, it can be seen that, at least above a specified threshold value, the sound pressure level at the output, i.e. the output level, increases more slowly than the sound pressure level at the input, i.e. the input level .

Proceeding from this, the invention is based on the object of specifying an advantageous method for adjusting a digital hearing aid. In addition, it is the object of the invention to specify an advantageously designed hearing aid and an advantageous computer program product.

This object is achieved according to the invention by a method having the features of claim 1, by a hearing aid having the features of claim 14 and by a computer program product having the features of claim 15. Preferred developments are contained in the dependent claims. The advantages and preferred configurations listed with regard to the method can also be transferred to the hearing aid and vice versa. In addition, the advantages and preferred configurations given with regard to the method can also be transferred to the computer program product and vice versa.

The method according to the invention serves to adjust a digital hearing aid. Conversely, a digital hearing aid according to the invention is set up in such a way that the method according to the invention can be carried out with it. The digital hearing aid, also referred to below as hearing aid for short, is typically designed in the manner of a hearing aid described above and has an input converter, a signal processing device and an output converter.

In this case, the input converter is used to generate digital input signals based on acoustic input signals which impinge on the hearing aid on the input side. For this purpose, the input converter expediently has an acousto-electric converter, ie in particular at least one microphone, and an analog/digital converter. The corresponding digital input signals are then processed in the signal processing device, digital output signals being generated based on the digital input signals. Finally, based on the digital output signals, acoustic output signals are generated by the output converter and emitted by the hearing aid on the output side, in particular into an auditory canal of a hearing aid wearer. In this case, the output converter typically has a digital-to-analog converter and an electro-acoustic converter, for example a loudspeaker.

The signal processing device is also set up to form an evaluation unit, a comparator unit and a pre-amplification unit. The corresponding units, ie the evaluation unit, the comparator unit as well as the pre-amplification unit, are typically formed by signal processing modules or data processing modules, in particular data processing modules of the type mentioned at the outset, ie for example by software program modules.

In the course of carrying out the method according to the invention, a first fitting session part is now carried out for fitting the hearing device, ie the digital hearing device, to a hearing device wearer, in particular the aforementioned hearing device wearer. In this case, an acoustic test signal is generated with the aid of an external test device, ie a test device which is not part of the hearing aid. The acoustic test signal is generated while the hearing aid is being worn by the hearing aid wearer, ie in particular by the hearing aid wearer for whom the hearing aid is intended and to whom the hearing aid is fitted. The hearing aid wearer is therefore in particular the so-called end customer.

A digital test input signal is then generated by means of the input converter of the hearing aid as a function of the acoustic test signal, that is to say a digital input signal which is dependent on the acoustic test signal. The generated acoustic test signal typically causes an acoustic input signal at the input of the hearing device and based on this input signal a digital input signal is then generated by the input converter, namely the digital test input signal.

It should be noted here that the generated acoustic test signal is generated, for example, by a loudspeaker or a plurality of loudspeakers of the external test device. The acoustic test signal is then further changed in particular by the spatial conditions, ie for example also by the hearing aid wearer. The acoustic input signal hitting the hearing aid on the input side is then dependent on the one hand on the acoustic test signal generated and on the other hand on the spatial conditions, which are also determined, among other things, by the shape of the head of the hearing aid wearer and in particular by the shape of the outer ears of the hearing aid wearer.

Furthermore, based on the test input signal, a sound pressure-dependent test variable is determined by means of the evaluation unit of the signal processing device. This sound pressure-dependent test variable is then compared by the comparator unit with a reference variable that is stored in the signal processing device, and a deviation is determined between the sound pressure-dependent test variable and the reference variable. A pre-amplification is then adjusted by the pre-amplification unit as a function of the deviation determined.

The corresponding pre-amplification is co-determining for the above-described mapping of the level range on the input side to the level range on the output side by the hearing device. However, the pre-amplification is typically an additional amplification in addition to the prior art amplification described at the outset. Therefore, the adjustment of the pre-amplification preferably takes place independently of a hearing deficit of the hearing device wearer. This means that with an adjusted pre-amplification, the hearing deficit of the hearing aid wearer is not taken into account. An amplification according to the prior art described at the outset is preferably additionally carried out by means of a main amplification by a main amplification unit.

It is also advantageous if pre-amplification is implemented, by means of which the sound pressure level on the input side is increased by a predetermined amount. In this case, a digital input signal is first generated by means of the input converter. This digital input signal represents a determined or metrologically recorded acoustic signal with a metrologically recorded sound pressure level value. The preamplification converts this digital input signal into a preamplified digital input signal, with the sound pressure level in the preamplified digital input signal being increased by the predetermined amount, starting from the sound pressure level value recorded by measurement. The increase by the specified amount takes place independently of the measured value of the sound pressure level. When converting digital input signals into pre-amplified digital input signals, a kind of offset shift of the sound pressure level. According to an alternative variant, input-side sound pressure levels are increased by a factor, namely a pre-amplification factor, by the pre-amplification.

Depending on the application, the aforementioned sound pressure-dependent test variable is, for example, a sound pressure level value. In such a case, the reference quantity is then expediently given by a sound pressure level value. According to an advantageous alternative, the circuit-dependent test variable and/or the reference variable is a variable that can be derived from a corresponding sound pressure level value. According to a further alternative, the sound pressure-dependent test variable is, for example, a mathematical function which assigns different sound pressure level values to different frequencies, or a group of several sound pressure level values for several frequency ranges.

Furthermore, the acoustic test signal is preferably given by a noise signal or a sequence of consecutive noise signals. Regardless of this, a sound pressure level value is preferably specified for the acoustic test signal. The specification of the sound pressure level value takes place, for example, based on information in a specified digital test signal, which is preferably used to generate the acoustic test signal using the external test device.

If a sound pressure level value is now specified for the acoustic test signal, the sound pressure level value (SPL: sound pressure level) is preferably between 60 dB and 80 dB, that is to say at 65 dB, for example.

It is also advantageous if only the aforementioned acoustic test signal with the specified sound pressure level value is used for the purpose of adjusting the pre-amplification by the pre-amplification unit. It is then preferred not to use a further acoustic test signal with a further sound pressure level value for this. At the very least, however, the use of a further sound pressure level value is preferably dispensed with. So will be several acoustic test signals are used, the same sound pressure level value is preferably specified for all.

In the case of the first fitting session part described above, it is generally not necessary to generate acoustic output signals. For this reason, this is not done in some applications. Irrespective of whether acoustic output signals are generated by the hearing aid in the first part of the fitting session, there is preferably no measurement of corresponding acoustic output signals, in particular by means of an external probe of the testing device. For example, there is no need to insert a microphone of the testing device into the auditory canal of the hearing aid wearer.

It is also expedient if the digital hearing aid is in the form of a multi-channel hearing aid. In this case, preferably 4 to 10 channels are realized. In such an embodiment of the digital hearing aid, the signal processing device first expediently carries out a channel-dependent and thus frequency-dependent separation or splitting of a digital input signal into a plurality of partial signals. Each partial signal reproduces a frequency range of the digital input signal that is assigned to a channel. The resulting partial signals are then preferably further processed in the individual channels independently of one another and finally combined to form the digital output signal.

Alternatively, a channel-dependent and thus frequency-dependent separation or splitting takes place even before digitization by the aforementioned analog-to-digital converter of the input converter, ie at the analog level. In both cases, however, the aforementioned digital sub-signals are ultimately generated and subsequently processed further.

In an advantageous development, an evaluation unit, a comparator unit and a pre-amplification unit of the type described above are then implemented for each channel, and the pre-amplification of the type described above is further preferably adapted for each channel.

In this case in particular, the acoustic test signal or at least the digital test signal on which it is based preferably contains a component for each channel or at least a plurality of components for a plurality of channels. In this case, each component is typically given by a noise signal in a predetermined frequency band. The parts are then lined up in a sequence, for example. Alternatively, a separate acoustic test signal is generated for each channel.

It is also advantageous if a pre-fitting session is part of the method according to the invention. In such a pre-adaptation session, a predetermined digital test signal, in particular the aforementioned digital test signal, is then used in order to generate an acoustic reference signal using an external reference test device. The corresponding reference test device is in turn not part of the hearing device and it is also preferably a device that is different from the aforementioned external test device. The reference test device typically has at least one loudspeaker and also a test fixture, such as a holding arm or an artificial head. During the generation of the acoustic reference signal, the digital hearing aid is held by the test fixture.

The first adaptation session part and the pre-adaptation session are therefore two method parts or sub-processes that are expediently executed at different times. In this case, the pre-fitting session is typically carried out before the first fitting session part. In addition, the pre-adaptation session preferably takes place at the manufacturer of the digital hearing aid, while the first adaptation session part preferably takes place at a service provider, such as a hearing aid acoustician. Apart from that, so-called laboratory conditions are typically present in the pre-adaptation session, which are also specified in particular by the test fixture. In contrast, in the first part of the fitting session, conditions that are close to reality are simulated in that the hearing aid is worn by the hearing aid wearer.

In the pre-adaptation session, the predetermined digital test signal is now used in order to generate the acoustic reference signal using the external reference test device. Furthermore, a digital reference input signal is then generated by means of the input converter as a function of the acoustic reference signal, ie a digital input signal based on the acoustic reference signal. The acoustic reference signal causes an acoustic input signal at the input of the digital hearing aid, which is dependent on the reference test device, and based on this acoustic input signal, the digital input signal dependent on the acoustic reference signal, namely the digital reference input signal, is generated by means of the input converter. Furthermore, based on the digital reference input signal, the aforementioned reference variable is determined by means of the evaluation unit and this reference variable is then stored in the signal processing device, ie in particular stored in a permanent memory.

The aforementioned predetermined digital test signal is also usually used to generate the acoustic test signal using the external test device. This is then done during what was previously referred to as the first fitting session part of the process. It should be pointed out here that the specified digital test signal in the pre-fitting session usually causes a different acoustic input signal at the input of the hearing device than in the first part of the fitting session. The reason for this are the differences in the existing conditions, which are determined by the devices used, ie the reference test device on the one hand and the test device on the other hand, and by the different environmental conditions for the hearing aid. The hearing aid is held by the test fixture and worn by the hearing aid wearer.

Variants of the method are also advantageous in which the preamplification unit precedes the evaluation unit. This means that in the order of the signal processing in the signal processing device, i.e. in the order of the individual process steps or method steps of the signal processing, first the amplification unit is applied to a signal and only in the further course of the signal processing is the evaluation unit applied. The pre-amplification and then the evaluation therefore preferably take place first. Depending on the application, the pre-amplification is then adapted, for example, based on a preset pre-amplification. In some cases, a kind of control circuit is then implemented, by means of which the pre-amplification is adjusted until the test variable and reference variable match and no more deviations are determined.

As already indicated above, it is also expedient if the signal processing device is set up to form a main amplification unit. Such a main amplification unit is also typically formed by a signal processing module or data processing module, in particular a data processing module of the type mentioned initially, ie for example by a software program module. It is also downstream of the pre-amplification unit, that is to say downstream in particular in terms of signal processing, and is preferably used to implement an amplification according to the prior art described at the outset. The amplification by the main amplification unit is hereinafter referred to as the main amplification.

In an advantageous development, the preamplification unit and the main amplification unit work independently of one another. In this case, the main amplification unit typically operates in the manner of an amplification unit according to the prior art, but the main amplification unit is fed with signals which are preamplified by the pre-amplification unit. These preamplified signals are then usually processed by the main amplification unit in the same way as the digital input signals are processed by a prior art amplifier unit. The main amplification unit therefore preferably has no knowledge of the pre-amplification unit and accordingly the effect of the pre-amplification unit is then not taken into account by the main amplification unit. Irrespective of this, the pre-amplification unit preferably works in a non-compressive manner, whereas the main amplification unit preferably works in a compressive manner, ie shows a compressive behavior.

If a previously described main amplification unit is now provided and implemented by the signal processing device, the method preferably has a further part or process which is referred to below as the second fitting session part. In this second adjustment session part, the main gain is preferably adjusted by the main gain unit. In this case, the second adaptation session part is expediently carried out after the first adaptation session part has ended. The main amplification is further preferably adjusted as a function of a hearing deficit of the hearing aid wearer and accordingly the second adjustment session part typically corresponds to a classic adjustment session according to the prior art, at least with regard to the adjustment of the signal processing device.

The second adaptation session part preferably takes place at a service provider, such as a hearing aid acoustician. In addition, the first fitting session part preferably takes place at a service provider, such as a hearing aid acoustician. More preferably, both parts, ie the first and the second part of the fitting session, are carried out by a service provider, such as a hearing aid acoustician, and in particular by the same service provider. The pre-fitting session, on the other hand, preferably takes place at the manufacturer of the digital hearing aid.

It is also advantageous if the main amplification unit is downstream of the evaluation unit, ie if the main amplification unit is downstream of the evaluation unit in terms of signal processing. The evaluation is then carried out by the evaluation unit and in particular the determination of the circuit-dependent test variable in the first part of the adaptation session before the main amplification and thus in particular also independently of the main amplification by the main amplification unit.

In addition, it is favorable if the circuit-dependent test variable is stored in the signal processing device, that is to say is stored, for example, in a permanent memory of the signal processing device.

In addition, it is advantageous if the signal processing device automatically recognizes which digital test signal is used during the first fitting session part to generate the acoustic test signal or at least whether the provided digital test signal is used. In such a case, it is also advantageous if the preamplification is only adapted if a reference variable that correlates with the recognized digital test signal is stored in the signal processing device. In this way it can be avoided that the wrong signal is accidentally used for an adjustment of the preamplification.

In an advantageous development, a number of digital test signals are then available for selection, and a reference variable is stored in the signal processing device for each of a number of digital test signals. The hearing device is then preferably set up in such a way that the signal processing device recognizes which digital test signal from the selection is being used. As a result, the signal processing device then selects the correcting reference variable using the recognized digital test signal for the adjustment of the pre-amplification and uses this reference variable for a comparison with the test variable.

The method according to the invention described above serves to adapt a hearing aid according to the invention and is designed accordingly for this purpose. Conversely, the hearing aid according to the invention is set up in at least one operating mode to carry out the method according to the invention. For this purpose, the hearing aid has in particular the signal processing device described above. A number of method steps of the method are then preferably carried out with the aid of the signal processing device, for which purpose an executable program is more preferably stored or installed in the signal processing device which, after a start, increases the number of method steps of the procedure automatically. The previously mentioned data processing modules are preferably implemented with the help of the program.

A corresponding program can also be subsequently installed or stored using a computer program product according to the invention. That computer program product is typically a file or a data carrier with a file, the file containing the executable program, ie in particular a suitable program code.

The previously described implementation of a preamplification unit and the adjustment of the preamplification in the course of the described adjustment in the first part of the fitting session is not only advantageous with regard to the execution of the main function of the hearing aid, i.e. the amplifier function, but also with regard to known auxiliary functions which the digital input signals are used in any way according to the state of the art. If such an auxiliary function is implemented in the hearing aid according to the invention, it is preferably adapted in such a way that the preamplified digital input signals are used instead of the digital input signals.

An example of such an auxiliary function is the so-called adaptive directionality. Here, for example, the preamplified digital input signals are then used to activate and/or control noise suppression algorithms. Such algorithms are often based on an estimate of the ambient noise, which can be incorrect if there are deviations on the input side.

Another example of such an auxiliary function is the so-called Microphone Noise Reduction (MNR), also known as Low Level Expansion. This very simple algorithm is based on massively reducing the hearing aid gain and thus the audible inherent noise in very quiet situations. If the hearing aid perceives a higher level, the amplification must be brought back to the desired level very quickly in order to improve speech intelligibility not to affect. Such an algorithm would of course be impaired in its function by an individual deviation of the input level.

Another example of such an auxiliary function is a so-called classification. This is a hearing aid function that attempts to classify the acoustic environment and then, depending on the acoustic class, change the configuration/function of the hearing aid. In concrete terms, this means, for example: if the hearing aid recognizes from the input signal that it is in a motor vehicle, the directionality of the hearing aid is changed in such a way that the primary hearing direction is no longer from the front, but is controlled to the side or to the rear. The so-called acoustic cues, on which the classification is based, depend in part on the spectral levels of the input signal.

FIG 1

in einem Blockschaltbild ein digitales Hörgerät in einer externen Referenz-Prüfeinrichtung,

FIG 2

in einem Blockschaltbild das digitale Hörgerät in einer externen Prüfeinrichtung sowie

FIG 3

in einem Diagramm zwei Verstärkungskurven.

Exemplary embodiments of the invention are explained in more detail below using a schematic drawing. Show in it:

FIG 1

in a block diagram, a digital hearing aid in an external reference test facility,

FIG 2

in a block diagram, the digital hearing aid in an external testing facility and

3

in a diagram two gain curves.

Corresponding parts are provided with the same reference symbols in all figures.

A hearing aid 2 described below as an example is in 1 shown schematically. It is designed as a digital hearing aid 2 and has an input converter 4 , a signal processing device 6 and an output converter 8 .

The input converter 4 is used to generate digital input signals based on acoustic input signals which are sent to the hearing aid 2 on the input side hit. For this purpose, the input converter 4 has a microphone 10 and an analog/digital converter 12 in the exemplary embodiment. The corresponding digital input signals are processed in the signal processing device 6, digital output signals being generated based on the digital input signals. Acoustic output signals are generated by the output converter 8 based on the digital output signals and emitted by the hearing device 2 on the output side. Here, the output converter 8 according to 1 a digital-to-analog converter 14 and a loudspeaker 16 .

The signal processing device 6 is also set up to form a plurality of data processing modules or software program modules, namely an evaluation unit 18, a comparator unit 20, a preamplification unit 22 and a main amplification unit 24. The signal processing device 6 also has a permanent memory 26.

To adjust the hearing aid 2, the method described below as an example is used, which comprises at least three parts, namely a pre-fitting session (pre-fitting session), a first fitting session part (first fitting session part) and a second fitting-session-part.

Of these three parts, the pre-adaptation session is performed first in terms of time. It is preferably carried out by the manufacturer of the hearing aid 2. A reference test device 28 with a loudspeaker 30 and a test fixture 32 is used for the pre-fitting session. The test fixture 32 is in the form of an artificial head, for example. During the pre-fitting session, the hearing aid 2 is held by the test fixture 32, as shown in 1 is indicated.

In the course of the pre-adaptation session, a predetermined digital test signal is used in order to generate an acoustic reference signal using the loudspeaker 30 of the reference test device 28 . As a result, a digital signal is then generated by means of the input converter 4 as a function of the acoustic reference signal Generates a reference input signal, i.e. a digital input signal based on the acoustic reference signal. In addition, based on the digital reference input signal, a reference variable is determined by the evaluation unit 18 of the signal processing device 6 and this reference variable is then stored in the permanent memory 26 of the signal processing device 6 .

The digital test signal, which is available as a file, for example, is preferably a noise signal and in particular a noise signal with a predetermined sound pressure level value of 65 dB, for example. By playing back the digital test signal using the loudspeaker 30 of the reference test device 28 , noise is then generated as an acoustic reference signal, which noise is based on the digital test signal and is influenced by the reference test device 28 .

In the exemplary embodiment, the sound pressure level value of the noise is now determined as a reference quantity by the evaluation unit 18 of the signal processing device 6 in the course of the pre-adaptation session, with the sound pressure level value determined during the pre-adaptation session being influenced by the reference test device 28, i.e. the loudspeaker 30, the test fixture 32 and the rest of the surroundings of the hearing aid 2, and through the components of the hearing aid 2, such as the microphone 10.

The other two parts of the method mentioned, ie the first fitting session part and the second fitting session part, are carried out in the exemplary embodiment by a service provider, for example a hearing aid acoustician. The first adjustment session part is carried out first and then the second adjustment session part. A testing device 34 with a loudspeaker 36 is used at least for the first part of the fitting session, and the hearing device 2 is worn by a hearing device wearer 38 during the first part of the fitting session.

In the course of the execution of the first adaptation session part, the digital test signal is used to test device 34 with the aid of loudspeaker 36 to generate an acoustic test signal. A digital test input signal is then generated by means of the input converter 4 of the hearing aid 2 as a function of the acoustic test signal, ie a digital input signal which is dependent on the acoustic test signal. Furthermore, based on the digital test input signal, a sound pressure-dependent test variable is determined by means of the evaluation unit 18 of the signal processing device 6 . This sound-pressure-dependent test variable is then compared with the reference variable stored in the permanent memory 26 of the signal processing device 4 using the comparator unit 20, and a deviation is determined between the sound-pressure-dependent test variable and the reference variable. A pre-amplification is then adjusted by the pre-amplification unit 22 as a function of the deviation determined.

The playback of the digital test signal using the loudspeaker 36 of the test device 34 generates noise as an acoustic test signal, which is based on the digital test signal and is influenced by the test device 34 . In the course of the execution of the first part of the adaptation session, the sound pressure level value of the noise is then determined in the exemplary embodiment by the evaluation unit 18 of the signal processing device 6 as a sound-pressure-dependent test variable, the sound pressure level value determined during the first part of the adaptation session being influenced by the test device 34, i.e. in particular the loudspeaker 36, through the rest of the surroundings of the hearing aid 2, i.e. also through the hearing aid wearer 38, and through the components of the hearing aid 2, such as the microphone 10.

Therefore, during the pre-adaptation session and during the first part of the adaptation session, two different sound pressure level values are typically determined by the evaluation unit 18 of the signal processing device 6 despite the same digital test signal. These two sound pressure level values are compared with one another and a type of compensation is preferably carried out by adapting the preamplification by the preamplification unit 22 of the signal processing device 6 . The pre-amplification by the pre-amplification unit 22 is preferably adjusted in such a way that the sound pressure level value determined during the first part of the adjustment session towards sound pressure level value determined during the pre-fitting session.

The pre-amplification is an additional amplification in addition to the main amplification by the main amplification unit 24. In the exemplary embodiment, the pre-amplification is adjusted independently of a hearing deficit of the hearing device wearer 38.

In contrast to the pre-amplification, the main amplification is adjusted by the main amplification unit 24 to the hearing deficit of the hearing device wearer 38 . This occurs in the second part of the adaptation session after the completion of the first part of the adaptation session.

It is also expedient if the digital hearing aid 2 is designed as a multi-channel hearing aid. In this case, preferably 4 to 10 channels are realized. In such an embodiment of the hearing aid 2, the signal processing device 6 first performs, for example, a channel-dependent and thus frequency-dependent separation or splitting of a digital input signal into a plurality of partial signals. Each partial signal reproduces a frequency range of the digital input signal that is assigned to a channel. The partial signals resulting from this are then preferably further processed in the individual channels independently of one another and finally combined to form a digital output signal.

In an advantageous development, a previously described signal processing is then implemented for each channel by means of an evaluation unit 18, a comparator unit 20, a preamplification unit 22 and a main amplification unit 24. This means that the in 1 and 2 data processing modules shown in the signal processing device 6 are implemented.

Irrespective of this, the pre-amplification unit 22 is preferably upstream of the evaluation unit 18 in terms of signal processing. D. h. That in the order of signal processing in the signal processing device 6, so in the Order of the individual process steps or method steps of the signal processing, first the pre-amplification unit 22 is used and only in the further course of the signal processing is the evaluation unit 18 used. Furthermore, the main amplification unit 22 is preferably located downstream of the evaluation unit 18 in terms of signal processing.

In most cases, the signal processing device 6 is also set up to form an additional data processing module, namely a module for noise suppression 40. In this case, the noise suppression 40 is preferably downstream of the main amplification unit 22 in terms of signal processing.

The basic idea of the invention is explained below using a schematic diagram, which 3 is reproduced:
Shown here is the sound pressure level Lo at the output of a digital hearing device, in short the output level, as a function of the sound pressure level L _I at the input of the hearing device, in short the input level. The curve shown as an example with a solid line shows two so-called knee points at 50 dB and at 65 dB.

For reasons of clarity, a simplified case is considered here, in which the sound pressure level L I recorded by the hearing device, i.e. in particular the sound pressure level L _I recorded under everyday conditions (hearing device is worn by the hearing device wearer), is affected by effects on the input side, such as shadowing of _the hearing device microphones , is lower by an amount of 7 dB than originally assumed, i.e. especially under laboratory conditions (hearing aid is fixed to an artificial head). In addition, only the difference at two different input levels is considered below.

The solid curve now shows the output level of the hearing aid as a function of the input level. The hearing aid works compressively, ie there are certain points, here the two knee points mentioned above, from which the output level rises more slowly than the input level. The knee points are usually set in such a way that a desired output level is achieved for a specific input signal, such as speech-simulating noise at low and medium input levels.

In the case considered here, the level that the hearing aid detects is now 7 dB lower than expected due to shadowing on the input side, i.e. especially under everyday conditions. In 3 four level values are marked by dashed lines as an example, namely two expected level values L _I,E1 and L _I,E2 and two associated level values L _I,A1 and L _I,A2 actually detected. In both cases, the actually recorded level value is 7 dB below the expected level value due to the shadowing on the input side.

This results in the hearing aid output level deviating from the desired or target value. However, due to the compressive behavior of the hearing aid, this deviation DL is not constant. While for low input levels it corresponds exactly to the difference in the input, i.e. 7 dB when comparing L _I,A1 and L _I,E1 , it is significantly lower for medium input levels, namely 2.8 dB when comparing L _I,A2 and L _I,E2 . This is also the fundamental problem with such input-side effects.

If only a single measurement is then carried out at a test level, the level dependency cannot be fully recorded. Because if a measurement is carried out at a low input level, it is determined that the output level of the hearing aid is 7 dB too low. If this deviation is not compensated on the input side according to the invention, but on the output side according to the prior art, ie by means of the standard amplification stage, ie linearly, this leads to overcompensation at medium input levels. Such an output-side compensation according to the prior art, in principle, shifts the curve in 3 towards the dashed curve. In the example, the output level of the hearing aid at medium levels, i.e. when comparing L _I,A2 and L _I,E2 , would be 4.2 dB too high.

Classically, the output level of the hearing aid would have to be measured at several input levels and the knee points would be shifted as a correction. But this has several disadvantages. Among other things, the measuring effort is relatively high. Furthermore, the repeatability of the measurement is low, especially at low input levels. In addition, a measurement at high input levels is necessary in principle, which is uncomfortable for the hearing aid wearer. Of particular importance, however, is that shifting the knee points only corrects the output level of the hearing aid. Many adaptive algorithms, such as background noise estimation or directionality control, are not corrected by this measure

In contrast, an additional (pre-) amplification stage before the (skin) amplification stage with compressive behavior causes a complete compensation of the effect on the input side. An increase in the (pre-)amplification of 7 dB has the effect that the level values actually recorded, ie also L _I,A1 and L _{I,A2 ,} are shifted to the expected level values, ie L _I,E1 or L _I,E2 and the hearing aid works absolutely correctly in relation to the output level, but especially in relation to adaptive, level-dependent signal processing algorithms.

In principle, only a single measurement is then necessary at a test signal level which, on the one hand, has a sufficient signal-to-noise ratio and, on the other hand, is not uncomfortably loud. In this measurement, the input of the hearing device is first measured in the method described and corrected if necessary. The measurement of the hearing aid output can then be corrected by linear amplification of the second amplification stage.

Reference List

2

hearing aid

4

input converter

6

signal processing device

8th

output converter

10

microphone

12

Analog to digital converter

14

Digital to analog converter

16

speaker

18

valuation unit

20

comparator unit

22

preamp unit

24

main reinforcement unit

26

permanent storage

28

reference test facility

30

speaker

32

test fixture

34

testing facility

36

speaker

38

hearing aid wearer

40

noise reduction

Lo

output level

LI

input level

LI,E1

expected level value 1

LI,E2

expected level value 2

LI,A1

detected level value 1

LI,A2

detected level value 2

Claims (15)

Method for adjusting a digital hearing aid (2), which has an input converter (4), a signal processing device (6) and an output converter (8),
whereby - the signal processing device (6) is set up to form an evaluation unit (18), a comparator unit (20) and a pre-amplification unit (22), - An acoustic test signal is generated by means of an external test device (34) while the hearing aid (2) is being worn by a hearing aid wearer (38), - a digital test input signal is generated by means of the input converter (4) depending on the acoustic test signal, - based on the digital test input signal, a sound pressure-dependent test variable is determined by means of the evaluation unit (18), - a deviation is determined by means of the comparator unit (20) between the sound pressure-dependent test variable and a reference variable which is stored in the signal processing device (6), and - A pre-amplification is adjusted by the pre-amplification unit (22) as a function of the deviation determined. Method according to claim 1,
whereby - a predetermined digital test signal is used to generate an acoustic reference signal by means of an external reference test device (28), while the hearing aid (2) is held by a test fixture (32), - a digital reference input signal is generated by means of the input converter (4) depending on the acoustic reference signal, - the reference variable is determined based on the digital reference input signal by means of the evaluation unit (18) and - The reference variable is stored in the signal processing device (6). Method according to claim 2,
wherein the predetermined digital test signal is used to generate the acoustic test signal by means of the external test device (34). Method according to one of claims 1 to 3,
wherein the pre-amplification unit (22) precedes the evaluation unit (18). Method according to one of claims 1 to 4,
wherein the signal processing device (6) is set up to form a main amplification unit (24) which is downstream of the pre-amplification unit (22). Method according to claim 5,
wherein a main gain is adjusted by the main gain unit (24) after the pre-gain adjustment has been made. Method according to claim 6,
wherein the main amplification is adjusted as a function of a hearing deficit of the hearing device wearer (38). Method according to one of claims 5 to 7,
wherein the main amplification unit (24) is downstream of the evaluation unit (18). Method according to one of claims 1 to 8,
the sound pressure-dependent test variable being stored in the signal processing device (6). Method according to one of claims 2 to 8,
whereby - the reference variable is linked to an identification feature which assigns the reference variable to the underlying digital test signal, and - the reference variable with its associated identification feature is stored in the signal processing device (6). Method according to claim 10,
whereby - a test feature is determined based on the digital test input signal by means of the evaluation unit (18) and - A deviation between the test variable and a reference variable is only determined if the identification feature is determined as the test feature. Method according to one of claims 2 to 11,
whereby - several predetermined digital test signals are used one after the other in order to generate an acoustic reference signal by means of the external reference test device (28) while the hearing aid (2) is held by the test fixture (32), - a digital reference input signal is generated by means of the input converter (4) depending on the respective acoustic reference signal, - based on the respective digital reference input signal, a reference variable is determined by means of the evaluation unit (18), - each reference variable is linked to an identification feature which assigns the reference variable to the digital test signal on which it is based, and - The reference variables with their associated identification features are stored in the signal processing device (6). Method according to claim 12,
whereby - a digital test signal is selected from the specified digital test signals, - the selected digital test signal is used to generate the acoustic test signal by means of the external test device (34), - a digital test input signal is generated by means of the input converter (4) depending on the test signal, - based on the test input signal, a sound pressure-dependent test variable is determined by means of the evaluation unit (18), - a test feature is determined based on the test input signal by means of the evaluation unit (18), - the test feature is compared with the stored identification features by means of the comparator unit (20) and the identification feature that corresponds to the test feature is determined, - by means of the comparator unit (20), a deviation is determined between the test variable and the reference variable, which is linked to the identified identification feature, and - A pre-amplification is adjusted by the pre-amplification unit (22) as a function of the deviation determined. Hearing aid (2) set up to carry out at least one method step of a method according to one of the preceding claims in at least one operating mode. Computer program product containing a program that can be executed on a data processing unit, in particular a digital signal processing device (6) of a digital hearing aid (2), which automatically executes at least one method step of a method according to one of the preceding claims after starting.

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