EP3576433B1 - Method for reduction of acoustic feedback in a hearing aid - Google Patents

Description

The invention relates to a method for reducing the occurrence of acoustic feedback in a hearing aid, with a first wearing situation being established which defines a positioning of the hearing aid relative to the wearer, with a first use situation being established for the first wearing situation, and with a specification for a Adjusting at least one hearing aid parameter takes place.

The occurrence of acoustic feedback poses a particular problem in the operation of a hearing aid Signal processing of the hearing aid in which an amplification is applied to the signal from the input transducer. If the attenuation factor by which the sound from the output transducer is attenuated on the sound path to the input transducer is lower than the amplification factor of the signal processing, the system can become unstable as a result of the closed amplification loop. This can be heard as a whistling sound at the relevant frequencies and therefore leads to a considerable impairment of the wearer's hearing.

One of the common measures for suppressing such acoustic feedback is to reduce the amplification of the signal processing when the feedback is registered. The reduction in gain can be limited to those frequency ranges in which the feedback occurs. However, this has the disadvantage that the amplification of the signal processing is no longer selected solely as a function of the wearer's individual hearing impairment, so that an output sound signal generated by the output transducer is no longer optimally matched to the wearer's audiological needs. It is also possible to suppress the acoustic feedback by means of an adaptive filter by implementing an electrical feedback loop. However, this can result in artifacts in the output sound signal due to the electronic cancellation of signal components.

In addition, the occurrence of acoustic feedback is largely dependent on the specific usage situation. While, for example, no feedback is to be expected in normal operation at a given frequency due to the ratio of attenuation in the acoustic feedback path and amplification in the electronic signal processing, the acoustic feedback path can affect changes such as using a mobile phone or putting on headgear can be changed so that the attenuation is reduced, and thus a critical feedback loop occurs. Such a spontaneous occurrence of feedback often leads to a whistling noise that is perceived as unpleasant in the described measures for suppression.

the EP 2 869 600 A1 calls for a hearing aid suppression of acoustic feedback by means of a compensation signal which is subtracted from an input signal of the hearing aid, with an estimation of a residual feedback which is not suppressed by the compensation signal. A gain parameter in the hearing aid is adapted on the basis of the residual feedback.

the US 2010/0 260 365 A1 calls a hearing aid with two different units for detecting acoustic feedback on the hearing aid, the respective output signals of the two units being able to indicate respective probabilities of acoustic feedback, and for example in a comparator circuit be compared with one another or with a predetermined limit value. The two units for detecting the acoustic feedback can differ, for example, in a time constant, so that one of the units reacts particularly quickly, the other detects feedback more slowly but more reliably.

The invention is based on the object of specifying a method by which a spontaneous occurrence of feedback is reduced in certain situations, which should have as little influence as possible on the output signals generated based on the input signals according to the individual hearing impairment of the wearer of the hearing aid.

The stated object is achieved according to the invention by a method for reducing the occurrence of acoustic feedback in a hearing aid, with a first wearing situation being established which defines a positioning of the hearing aid relative to the wearer, with a first use situation being established for the first wearing situation, which is established by at least one body movement of the wearer of the hearing aid and / or at least one relative position of an external object to the wearer's body is characterized, and a plurality of frequency-resolved curves of a feedback tendency of the hearing aid is determined for the first use situation. It is provided here that a first criticality measure is determined on the basis of each frequency-resolved curve for the first use situation, which contains information on a frequency range that is critical with regard to the occurrence of acoustic feedback and a corresponding relative probability for an occurrence of acoustic feedback, with that for a given frequency First criticality measure for the first user situation based on a scatter measure for the values of the feedback tendency resulting from the plurality of frequency-resolved curves in each case at this frequency, a second use situation being established for the first wearing situation, with a second criticality measure in one for the second use situation is determined in an analogous manner to how the first criticality measure for the first usage situation, and based on the entirety of the first criticality measure and the second criticality measure a specification for adapting at least one hearing aid parameter is made. Advantageous and in part inventive embodiments are the subject matter of the subclaims and the following description.

A wearing situation is to be understood here in particular as the entirety of the circumstances under which the hearing aid is locally fixed on the wearer, and in particular an exchangeable acoustic coupling piece (such as an ear mold or a so-called "dome") that may be present assumes a certain position . In this respect, two wearing situations can differ with regard to the exact spatial position of the hearing aid and / or the acoustic coupling piece, or they can also be given by using different acoustic coupling pieces. A usage situation here and in the following includes in particular that the wearer of the hearing aid carries out body movements during operation, in particular in a specific wearing situation, or moves himself relative to limiting objects such as walls or windows, so that the movements occurring in the usage situation are particularly suitable for this are to influence an acoustic feedback path of the hearing aid.

A feedback tendency of the hearing aid includes, in particular, a frequency-dependent parameter, on the basis of which a quantitative probability of an acoustic feedback occurring at the relevant frequency can be determined. In particular, a tendency towards feedback can be given here by a ratio or a difference between an attenuation of the acoustic feedback path and a gain due to signal processing taking place in the hearing aid. A frequency-resolved curve of a feedback tendency can in this respect be given by the respective values of the feedback tendency over the corresponding frequency spectrum, or by the values of the feedback tendency at a plurality of support points for the frequency, which are to be selected with a sufficiently high frequency resolution.

The first criticality measure for the feedback tendency is also determined on the basis of a weighting of the values of the various curves at a given frequency determined. In this case, the criticality measure is preferably calculated in such a way that at a given frequency for a high variance of values of the feedback tendencies of the various curves a higher value is generated for the first criticality measure than in a situation with an identical maximum value of the feedback tendencies with a lower one Variance. This takes into account the fact that at a certain frequency for a high variance of the values of the feedback tendency in the first use situation, an even further spread beyond the decimal value recorded in the measurement is to be expected, while a low variance of the values at a given frequency speaks for a greater intrinsic stability of the system. In this sense, based on the maximum values of the feedback tendency and based on the variation across the various curves at a given frequency, it is possible to infer the risk of feedback occurring at the corresponding frequency for the first use situation. The relative probability of such an occurrence of the feedback can in particular also be related to other frequency ranges, so the first criticality measure in particular make a statement that feedback is more likely for a first frequency than for a second frequency if the value of the first Criticality measure at the first frequency is greater than the value at the second frequency.

The at least one hearing aid parameter is preferably adapted in accordance with the specification made on the basis of the first criticality measure, it being possible for the adaptation in particular to take place automatically. As an alternative to this, the adjustment can also be carried out manually by a hearing aid acoustician in accordance with the specification. In this case, the at least one hearing aid parameter is preferably adapted with the additional specification of impairing signal amplification and reproduction dynamics in the hearing aid as little as possible. This can take place in particular in that the at least one hearing aid parameter is only adapted for that frequency range for which, on the basis of the first criticality measure, an occurrence of feedback in the first use situation is considered to be sufficiently likely at all. The evaluation can be done by a threshold comparison of the frequency-resolved first criticality measure over the entire spectrum.

By adapting the at least one hearing aid parameter based on the first criticality measure, on the one hand the probability of feedback occurring can be limited in a targeted manner to those frequency ranges in which a change in the present hearing aid parameters is necessary in order to avoid feedback, thereby adapting the reproduction properties the hearing aid can be designed "minimally invasive". Previous methods for reducing or suppressing feedback, which are based on an adaptation of hearing aid parameters, usually check the occurrence of feedback in a frequency band. The adjustment of the hearing aid parameters for the signals involved takes place with the smallest possible time delay for their checking, since it takes place during the ongoing operation of the hearing aid. As a result, on the one hand, only a limited number of frequency bands is available at the checking level, since otherwise the filters used for dividing an input signal into different frequency bands would cause too high a latency. On the other hand, the hearing aid parameters are set frequency band-wise at the level of adaptation, whereby, for example, if a gain factor in a frequency band is reduced, the reproduction for the entire frequency band is affected, while a critical probability for an occurrence of a There is feedback, and thus an adjustment of the gain would only be sufficient over this interval.

On the other hand, the first criticality measure and the described adaptation can be used to check whether the probability of feedback for the first feedback situation can really be reduced by the corresponding adaptation of the at least one hearing aid parameter. If this is not the case, this can be interpreted as an indication of a problem which, in the broadest sense, is related to the wearing situation of the hearing aid, and further measures can be coordinated accordingly.

According to the invention, a plurality of frequency-resolved curves of a feedback tendency is determined for the first usage situation, the first criticality measure for the first user situation being formed for a given frequency using a degree of dispersion of the values of the feedback tendency resulting from the plurality of frequency-resolved curves at this frequency. In particular, the first usage situation is continuously maintained, e.g. by maintaining and / or repeating a corresponding body movement. Specifically, this can be done in such a way that the body movement, which characterizes the first use situation, is repeated several times, and a plurality of curves of the feedback tendency are determined in the process. This can take place over a predetermined period of time, or until a predetermined amount of measured values and / or curves for the feedback tendency have been determined with sufficient measurement quality. Subsequently, the degree of dispersion for each frequency, i.e. the variance of the values for example, is calculated which the different curves show for the feedback tendency at this frequency, and the first criticality measure is formed on the basis of the determined variances for different frequencies.

By using a variance measure that provides information on how the values of the feedback tendency can differ at a given frequency over the first usage situation, those frequency ranges can be identified in which the feedback tendency is expected to be exceeded using the values determined in the present curves should be, and the at least one hearing aid parameter can also be adapted accordingly if none of the values determined for the feedback tendency is directly critical for feedback at a given frequency. At a given frequency, the degree of dispersion of the values for the feedback tendency can therefore be viewed as an indicator of the stability of the feedback path in the first use situation. In the case of a low value of the scatter, it is assumed that the values In real operation of the hearing aid in a reproduction of the first use situation, go only insignificantly beyond the determined value range for the given frequency, whereby the adaptation of the at least one hearing aid parameter can be further restricted, which has a positive effect on the playback properties of the hearing aid.

An attenuation of an acoustic feedback path is expediently measured, the tendency for feedback at a given frequency to be determined in each case on the basis of a signal amplification in the hearing aid and on the basis of the attenuation of the acoustic feedback path. In particular, the feedback tendency for a given frequency is determined as a sum or as a product of the attenuation of the acoustic feedback path and the signal amplification in the hearing aid. The attenuation of the acoustic feedback path can in particular be determined by means of an adaptive filter, or measured directly by means of a modulated test signal.

It proves to be advantageous if the first use situation is established by the wearer putting on a headgear, and / or a movement of the jaw of the wearer, and / or the wearer using a mobile phone near the hearing aid, and / or a sporty one Actuation of the carrier and / or a positioning of the carrier in the immediate vicinity of a spatial delimitation. In particular, a hat, a cap and a headscarf are included as headgear. In particular, the jaw movement can consist of a chewing movement or speaking. A spatial delimitation here includes in particular a window and a wall. The positioning is not tied to the movement process, but a purely static situation in the vicinity of the boundary can also be used. In particular, if the first use situation is present, a cumulative presence of the above-mentioned conditions is possible, for example, in that a headgear has been removed for a telephone call that is beginning. The mentioned possibilities for the first use situation cover a broad spectrum of situations that can occur in everyday life and in which an acoustic feedback path can in principle change.

In an advantageous embodiment of the invention, the at least one hearing aid parameter is selected from an overall gain at a frequency and / or a compression characteristic curve at a frequency and / or a readjustment speed. The compression characteristic curve at a frequency is defined here in particular by a compression ratio and a knee point. In particular, an immediately surrounding frequency interval can also be included in the overall amplification at a frequency. If the first criticality measure is determined essentially continuously via the frequency, then with regard to the probability of acoustic feedback, critical frequencies are usually not obtained in isolation - since with such a frequency the first criticality measure would have to assume its critical value exactly as a point of contact - but over an interval of frequencies. As the at least one hearing aid parameter, the overall gain or the compression characteristic curve in this interval, or also a readjustment speed of the adaptive filter, can now be adapted. The hearing aid parameters mentioned are suitable, on the one hand, for suppressing acoustic feedback through appropriate adaptation. On the other hand, their adaptation in the hearing aid is technically possible without any additional effort, so that there is no unnecessary burden on the signal processing.

According to the invention, a second use situation is established for the first wearing situation, a second criticality measure being determined for the second use situation, the second criticality measure being used to specify an adjustment of the at least one hearing aid parameter and / or a further hearing aid parameter. Here, the second criticality measure for the second usage situation is determined in a manner analogous to the first criticality measure for the first usage situation. This allows the probability of feedback occurring for different processes to be assessed individually, and the adaptation of one or more hearing aid parameters to be specified as a function of the totality of the assessments. The second usage situation is established by one of the processes mentioned for the first usage situation.

In a further advantageous embodiment, the at least one hearing aid parameter is adjusted according to the specification made using the first criticality measure, the hearing aid being operated with the adjusted hearing aid parameter in a test mode, the first use situation being established in the test mode, and the first use situation being set up in the test mode a third criticality measure is determined for, in particular, automatic checking of the adaptation. The third criticality measure is preferably determined in the manner described above, that is to say in particular in a manner analogous to the first criticality measure, which ensures that the values can be compared at a given frequency. In particular, the test operation can also consist of a resumption of regular operation of the hearing aid, with the aforementioned checking of the hearing aid parameter adjusted on the basis of the first criticality measure initially taking place using the third criticality measure, and regular operation simply being continued in the event of a positive assessment of the checking, and in In the event of a negative evaluation of the review, further measures are proposed. The test operation can, however, also be formed by an independent routine. In this case, the first usage situation is established within the framework of said routine, and the present setting of the hearing aid is checked by means of the third criticality measure, which setting comprises the adaptation of the at least one hearing aid parameter made on the basis of the first criticality measure.

It proves to be further advantageous if a second wearing situation is established, the first use situation being established for the second wearing situation, a fourth criticality level being determined for the first use situation in the second carrying situation, and a specification with regard to the fourth criticality level being established a suitability of the second wearing situation for the operation of the hearing aid takes place. The fourth criticality measure is preferably determined in the manner described above, in particular in a manner analogous to the first criticality measure and particularly preferably also to the third criticality measure, whereby the values of the first criticality measure and at least the fourth criticality measure, particularly preferably also the third criticality measure, can be compared is ensured at a given frequency. Establishing a second wearing situation can be particularly advantageous if the probability of feedback occurring in the first use situation cannot be significantly reduced by adjusting the hearing aid parameters, and this is determined in particular by checking the adjustment using the third criticality measure.

For example, a specification for changing the at least one hearing aid parameter can be made based on the first criticality measure, and this can be adapted accordingly under the secondary conditions that result from the requirements for the playback dynamics and volume for the wearer. The first usage situation is then established in the test mode and the third criticality measure for the adjusted settings is determined. If it is found that feedback is still critically probable even after the settings have been adjusted, preferably within the audiologically acceptable framework, this is assessed as an indication of a mechanical problem in the broadest sense, i.e. a change in the wearing situation can be recoverable.

On the basis of the fourth criticality measure, it is now checked in particular whether the settings already adjusted in the first step - on the basis of the first criticality measure - are suitable for regular operation of the hearing aid in the second wearing situation, i.e. in particular the likelihood of feedback - according to the criticality measure used as a criterion - is significantly reduced compared to the first wearing situation. A specification is therefore preferably made on the basis of the fourth criticality measure with regard to the suitability of the second wearing situation for operating the hearing aid with the at least one hearing aid parameter adapted on the basis of the first criticality measure

The second wearing situation is expediently produced by correcting the position of an acoustic coupling piece of the hearing aid, and / or using an acoustic coupling piece with changed dimensions, and / or using an acoustic coupling piece with a modified ventilation opening. An acoustic coupling piece here includes in particular an ear mold, a so-called “dome” and a so-called “earmould”. The measures mentioned represent, on the one hand, frequent sources of error when putting the hearing aid in its regular wearing position; by the wearer himself or a person of trust, without a visit to a hearing aid acoustician being necessary - and no further, more complex interventions on the hearing aid are required. Against this background, the first wearing situation is produced in particular by simply putting on the hearing aid - in accordance with the present mechanical configuration - in the supposed wearing position.

At least the first wearing situation and the first usage situation are expediently recorded by means of a video recording system. Acquisition by a video recording system can in particular enable a specialist, e.g. a hearing aid acoustician, to be omitted to reduce the likelihood of feedback, which is convenient for the wearer.

It also proves to be advantageous if image data generated by the video recording system are transmitted to a video playback system spatially separated from the carrier and reproduced by the latter, and / or an automatic command for determining the number of frequency-resolved curves of a feedback tendency based on the image data generated by the video recording system Hearing aid is generated in the first use situation. The automatic command can in particular be generated using facial or generally image recognition, which determines that the first usage situation has been properly established, e.g. by detecting a chewing or speaking movement of the jaw or the wearer bringing a mobile phone to the ear.

For example, the video playback system can be arranged in a hearing aid acoustician's work rooms, while the wearer is at home in the detection area of the video recording system. In response to a start signal from the hearing aid acoustician, upon which the determination of the feedback tendency should also begin, the wearer establishes the first use situation in the first wearing situation, e.g. by putting on a headgear or bringing a mobile phone to his ear. The first usage situation can now be ended on the one hand by the expiry of a fixed period of time, or on the other hand it can be ended when the determined curves for the feedback tendency no longer exceed their own extreme values or envelopes for a certain measurement period. The first criticality measure is now determined from the curves determined for the feedback tendency. An adaptation of the at least one hearing aid parameter is now specified on the basis of the first criticality measure. The adaptation itself can either be carried out by the wearer himself, by a person of trust of the wearer (in particular if the wearer is unable to do so himself), or via suitable remote access by the hearing aid acoustician.

After the adaptation has taken place, in response to a further start signal, the first usage situation can be established again in the test mode, and further curves of the feedback tendency can be determined, from which the third criticality measure is then determined. On the basis of the third criticality measure, it is now checked whether the adjustment of the settings has sufficiently reduced the tendency for feedback. If this is not the case, the hearing aid acoustician can instruct the wearer to create the second wearing situation, the specific selection of the measure being made using the third and possibly also using the first criticality measure - for example, via courses characteristic of certain errors and in particular can be specified automatically. If a measure is specified as the establishment of the second wearing situation, which the wearer cannot carry out independently, the person they trust can establish the second wearing situation via the video monitoring system under the instruction of the hearing aid acoustician.

The first use situation is now established in the manner described above in response to a start signal, and a new series of measurements of the feedback tendency is carried out to determine the fourth criticality measure, on the basis of which the suitability of the second wearing situation for suppressing feedback is assessed.

The invention also refers to a hearing aid which is set up to carry out the method described above. In particular, the hearing aid has means for detecting at least the attenuation of an acoustic feedback from an output transducer of the hearing aid to an input transducer. The hearing aid preferably also has means for transmitting a signal amplification and the attenuation resulting from the acoustic feedback to an external detection unit. In this case, parts of the method described above, such as the determination of the first and further criticality measures and the corresponding specifications, can take place in the external recording unit. As an alternative to this, the hearing aid preferably comprises means for calculating the first and further criticality measures.

• Fig. 1 in einem Blockschaltbild ein Hörgerät, in welchem eine akustische Rückkopplung auftritt,
• Fig. 2 in einem Blockdiagramm ein Verfahren zur Verringerung einer Rücckopplungsneigung in einem Hörgerät in Abhängigkeit einer Tragesituation,
• Fig. 3 in einem Diagramm eine Rückkopplungsneigung gegen eine Frequenz, und
• Fig. 4 in einem Diagramm eine Mehrzahl an Rückkopplungsneigungen für verschiedene Benutzungssituationen und ein hieraus resultierendes Kritikalitätsmaß.

An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. The following are shown schematically in each case:

• Fig. 1 a block diagram of a hearing aid in which acoustic feedback occurs,
• Fig. 2 in a block diagram a method for reducing a feedback tendency in a hearing aid as a function of a wearing situation,
• Fig. 3 in a diagram a feedback tendency against a frequency, and
• Fig. 4 in a diagram a plurality of feedback tendencies for different usage situations and a resulting criticality level.

Corresponding parts and sizes are provided with the same reference symbols in each of the figures.

In Figure 1 a hearing aid 1 is shown schematically in a block diagram. An input transducer 2 of the hearing aid 1, which in the present case is designed as a microphone, converts a sound signal 4 from the surroundings into an input signal 6. The input signal 6 is fed to a signal processor 8 in the hearing aid 1 and processed there in accordance with the audiological needs of the wearer of the hearing aid 1 and, in particular, is amplified as a function of the frequency band. The output signal 10 resulting from the signal processing 8 is converted by an output transducer 12 of the hearing aid 1 into an output sound signal 14, which is passed to the hearing of the wearer of the hearing aid 1, which is not shown in detail. In the present case, the output transducer 14 is provided by a loudspeaker which is arranged in an acoustic coupling piece 15 of the hearing device 1. In the present case, the acoustic coupling piece is given as an ear mold. Along an acoustic feedback path 16, part of the output sound signal 14 can now reach the input transducer 2 again, and thus find its way into the input signal 6, whereby a closed feedback loop is formed in which signal components are continuously amplified by the signal processing 8.

In order to suppress the acoustic feedback that occurs, the amplification can now be reduced in signal processing 8 on the one hand. However, this is also associated with a loss of amplification for other signal components not affected by the acoustic feedback, so that the signal processing 8 no longer works optimally in accordance with the audiological specifications of the wearer of the hearing aid 1. In order to be able to ensure suppression of the acoustic feedback, also taking these specifications into account, the output signal 10 is often branched off and fed to an adaptive filter 18.

This generates a compensation signal 20 which is fed to the input signal 6 and subtracted from it. The signal resulting from this subtraction finds its way into the signal processing 8 on the one hand and is also fed to the adaptive filter as an error signal 22 on the other hand. In the adaptive filter 18, in particular the acoustic feedback path 16 or its frequency response is estimated.

However, situations can also arise in which the subtraction of the compensation signal 20 from the input signal 6 leads to undesired effects such as artifacts in the output signal 10. The speed with which the estimate of the feedback path is updated is a variable time parameter of the adaptive filter 18. The shorter this time parameter is set, the faster the suppression of the feedback adapts to a change in the acoustic feedback path. However, the quick readjustment by the user can be perceived as an annoying artifact all the more frequently. In this respect, a trade-off should be chosen here for a pleasant sound experience, if possible without feedback.

In addition, the occurrence of acoustic feedback sometimes has predominantly mechanical causes, such as, for example, the acoustic coupling piece 15 of the hearing aid 1 not being optimally seated in the wearer's ear, as a result of which a particularly high proportion of the output sound signal 14 can escape and reach the input transducer 2 again. Further causes, which are essentially mechanical, can depend on a specific usage situation such as a chewing or speaking movement or the influence of a mobile phone or other similar object in the vicinity of the hearing aid 1 on the acoustic feedback path 16. In this case, on the one hand, the suppression of the feedback by the adaptive filter 18 with the risk of artifacts in the output signal 10 is not always effective. On the other hand, it can be useful or desirable to make the acoustic feedback that occurs depending on the specific usage situation more difficult in advance without significantly restricting the dynamics of the reproduction of the hearing aid 1.

This is in Figure 2 shown in a block diagram, which has a corresponding method as its subject. First of all, a first wearing situation 30 is produced in which the wearer uses the hearing aid 1 after Figure 1 is applied regularly. The first wearing situation 30 is characterized in particular by the global position of the hearing aid 1 relative to the wearer, and also by the use of individual, reversibly exchangeable components such as the acoustic coupling piece 15 and their positioning relative to the wearer. In the first wearing situation 30, a first use situation 32 is now produced, which is characterized by at least one body movement of the wearer and / or by an external object. This can be done, for example, by putting on headgear such as a hat or cap, by moving the wearer's jaw while speaking or chewing, or by using a mobile phone near the hearing aid. During the first use situation, a plurality of frequency-resolved curves, 34a-c of a feedback tendency of the hearing aid are determined. This is done in that, for example, by repeating the movement that speaks of the first use situations, the measurement process for the feedback tendency is repeated, and over time a plurality of "screenshots" of the feedback tendency is generated over the frequency. From the frequency-resolved curves 34a-c of the feedback tendency, a first criticality measure 36 is generated in a manner still to be described, on the basis of which a specification 38 is made for an adaptation of at least one hearing aid parameter.

In an analogous manner, not shown, a second usage situation can also be produced in the first wearing situation 30, in which frequency-resolved curves follow a feedback tendency of the hearing aid 1 Figure 1 can be determined from which a second criticality measure is determined. Using the second criticality measure determined in this way, a specification for the adjustment of one or more hearing aid parameters can then also be made, the specification on the one hand being able to relate to the hearing aid parameter (s) 40 for which a specification 38 for adaptation is already made based on the first criticality measure 36. On the other hand, the created on the basis of the second criticality measure Specification also relate to other hearing aid parameters for which no specification yet exists.

The hearing aid parameter 40 is now adapted in accordance with the specification 38 and possibly in accordance with a further specification created in a second use situation. The hearing aid parameter 40 can be, for example, an overall gain at a specific frequency and / or a compression characteristic curve at a specific frequency, but also a parameter of the adaptive filter 18 Figure 1 , for example by a readjustment speed or a step size. A test mode 42 is now started, in which the hearing device 1 is tested in the first use situation 32. Here again, frequency-resolved curves 44a-c are determined for the feedback tendency of the hearing aid. The frequency-resolved curves 44a-c are thus generated while the movement corresponding to the first usage situation is repeated in test mode 42. A third criticality measure 46 is generated from the frequency-resolved curves 44a-c in a manner analogous to the first criticality measure 36. On the basis of the third criticality measure 46 it can now be determined whether the adaptation of the hearing device parameter 40 according to the specification 38 has significantly reduced the probability of an acoustic feedback occurring during the first use situation 32.

If this is not the case, a second carrying situation 50 is suggested. This can be, for example, a position correction of the acoustic coupling piece 15 of the hearing aid 1, or the use of an acoustic coupling piece with changed dimensions and / or a changed ventilation openings. After the corresponding measure, which characterizes the second wearing situation 50, has been proposed, which can in particular take place automatically, the wearer of the hearing aid 1 or a person of trust establishes the second wearing situation. The first use situation is then established again for the second carrying situation 50 by means of the corresponding movement. Here again, frequency-resolved curves 54a-c are determined for the feedback tendency, on the basis of which a fourth criticality measure 56 is determined. On the basis of the fourth criticality measure 56 can now It can be checked whether the specification made according to the first criticality measure 36 for the adaptation of the hearing device parameter 40 in the second wearing situation 50 is suitable for keeping the probability of the occurrence of acoustic feedback sufficiently low. If this is the case, the second carrying situation 50 can be identified as a carrying situation to be used from now on, for example by continuing to use an acoustic coupling piece that may have been replaced, or by continuously ensuring that it is properly inserted when the acoustic coupling piece is put on Penetrates the ear canal. If the fourth criticality measure 56 does not suggest any significant improvement in the feedback tendency, either a third wearing situation (not shown in detail) can be produced in a manner analogous to the second wearing situation 50, or a visit to a hearing aid acoustician can be recommended as a "last resource" measure.

In Figure 3 In a diagram, a feedback tendency 60 in dB is plotted against the frequency f. The feedback tendency 60, which represents a measure of the probability of an acoustic feedback occurring, is formed here by following the attenuation 62 of the acoustic feedback path 16 Figure 1 (dashed line) the amplification 64 taking place in the signal processing 8 (dashed-dotted line) is added.

In Figure 4 a plurality of frequency-resolved curves 60a-m for the feedback tendency is shown. These correspond, for example, to various individual measurements that were carried out during the first usage situation Figure 2 be performed. While the individual curves 60a-m hardly differ from one another in the frequency range up to approx. 3 kHz, and thus the variance of the various curve values is hardly significant at a given frequency, the curves 60a-m drift noticeably apart from 3 kHz upwards. A narrow frequency range around 6 kHz should be mentioned in particular, in which the individual curves differ in their values by up to 30 dB. From 7 kHz upwards, the course of the curves is again almost uniform.

Using the curves 60a-m, a criticality measure 66 is now determined in a manner analogous to the first criticality measure 36, the third criticality measure 64 and the fourth criticality measure 56. This is done by adding a correction term to the maximum value 60m for the feedback tendency (dotted line) at each frequency f, which depends monotonically on the variance of the individual values of the curves 60a-m at a given frequency f. For the high variance, which is present at just below 6 kHz, the criticality measure 66 (dashed line) is maximum.

While the absolute values of the individual curves 60a-m in the range around 2 kHz are even higher than the maximum value 60m at approx. 4 kHz, due to the higher variance at 4 kHz, the criticality measure 66 is greater there than at 2 kHz. This takes into account the fact that the system is more stable over the entire range of possible values during the first use situation at 2 kHz than at 4 kHz, which is why it can be assumed that at 4 kHz the maximum value determined is not necessarily the absolutely possible Corresponds to the maximum value, while this is probably the case at 2 kHz due to the high stability. The criticality level is correspondingly higher at 4 kHz.

Frequency ranges 68 can now be identified from the criticality measure 66, for which the occurrence of acoustic feedback in the relevant usage situation is particularly likely and is to be adapted in accordance with a hearing aid parameter. For this purpose, the exceeding of a threshold value by the criticality measure 66 can be used as a criterion, whereby 0 dB - that is to say the limit for a critical gain - can be selected as the threshold value in a first approximation

Although the invention has been illustrated and described in more detail by the preferred exemplary embodiment, the invention is not restricted by this exemplary embodiment. Other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

List of reference symbols

1

Hearing aid

2

Input transducer

4th

Sound signal

6th

Input signal

8th

Signal processing

10

Output signal

12th

Output converter

14th

Output sound signal

15th

acoustic coupling piece

16

acoustic feedback path

18th

adaptive filter

20th

Compensation signal

22nd

Error signal

30th

first carrying situation

32

first usage situation

34a-c

frequency-resolved curves

36

first criticality measure

38

specification

40

Hearing aid parameters

42

Test operation

44a-c

frequency-resolved curves

46

third criticality measure

50

second carrying situation

54a-c

frequency-resolved curves

56

fourth criticality measure

60

Feedback tendency

60a-m

frequency-resolved curves (for feedback tendency)

60m

Maximum value

62

damping

64

Reinforcement

66

Criticality measure

68

Frequency range

Claims (11)

1. A method for reducing an occurrence of an acoustic feedback in a hearing device (1),
   wherein a first wearing situation (30) is established which determines a positioning of the hearing device (1) relative to the wearer,
   wherein for the first wearing situation (30), a first use situation (32) is established which is characterized by at least one body movement of the wearer of the hearing device (1) and/or at least one relative position of an external object with respect to the body of the wearer,
   wherein for the first use situation (32), a plurality of frequency-resolved curves (34a-c) of a feedback tendency (60) of the hearing device (1) is determined,
   wherein, on the basis of the frequency-resolved curves (34a-c), a first criticality measure (36) is determined for the first use situation (32), containing information on a critical frequency range (68) with respect to an occurrence of acoustic feedback and a corresponding relative probability of an occurrence of acoustic feedback,
   wherein, for a given frequency, the first criticality measure (36) for the first use situation (32) is formed based on a scattering measure for the values of the feedback tendency (60) at this frequency each of which resulting from the plurality of frequency-resolved curves (34a-c),
   wherein for the first wearing situation (30), a second use situation (32) is established,
   wherein for the second use situation, a second criticality measure is determined in a manner analogous to the first criticality measure for the first use situation, and
   wherein, on the basis of the totality of the first criticality measure (36) and the second criticality measure, a specification (38) for fitting at least one hearing device parameter (40) is made.
2. The method of claim 1,
   wherein an attenuation (62) of an acoustic feedback path (16) is measured, and
   wherein the feedback tendency (60) at a given frequency is determined on the basis of a signal gain in the hearing device (1) and on the basis of the attenuation (62) of the acoustic feedback path (16), respectively.
3. The method according to one of the preceding claims,
   wherein the first use situation (32) is established by

   - putting on a headpiece by the wearer, and/or

   - a jaw movement of the wearer, and/or

   - the use of a mobile phone in the proximity of the hearing device (1) by the wearer, and/or

   - a sporting activity of the wearer, and/or

   - a positioning of the wearer in close proximity to a spatial boundary.
4. The method according to one of the preceding claims,
   wherein the at least one hearing device parameter (40) is selected from

   - a total gain at a frequency, and/or

   - a compression characteristic curve at a frequency, and/or

   - a readjustment speed.
5. The method according to one of the preceding claims,
   wherein the at least one hearing device parameter (40) is adjusted according to the specification (38) made on the basis of the first criticality measure (36),
   wherein the hearing device (1) is operated with the adapted hearing device parameter (40) in a test operation mode (42),
   wherein in the test operation mode (42), the first usage situation (32) is established, and
   wherein for the first use situation (32) in the test operation mode, a third criticality measure (46) for monitoring the fitting is determined.
6. The method according to one of the preceding claims,
   wherein a second wearing situation (50) is established,
   wherein for the second wearing situation (50), the first use situation (32) is established,
   wherein for the first use situation (32) in the second wearing situation (50), a fourth criticality measure (56) is determined, and
   wherein a specification regarding a suitability of the second wearing situation (50) for operation of the hearing device (1) is made on the basis of the fourth criticality measure (56).
7. The method according to claim 5 in combination with claim 6,
   wherein on the basis of the fourth criticality measure (56), a specification is made regarding a suitability of the second wearing situation (50) for the operation of the hearing device (1) with the at least one hearing device parameter (40) as adapted on the basis of the first criticality measure (36).
8. The method according to claim 6 or claim 7,
   wherein the second wearing situation (50) is established by

   - a position correction of an acoustic coupling piece (15) of the hearing device (1), and/or

   - a use of an acoustic coupling piece (15) with modified dimensions, and/or

   - a use of an acoustic coupling piece (15) with a modified venting opening.
9. The method according to one of the preceding claims,
   wherein at least the first wearing situation (30) and the first use situation (32) are recorded by means of a video recording system.
10. The method according to claim 9,
    wherein image data generated by the video recording system is being transmitted to a video reproduction system spatially separated from the wearer, and reproduced by said video recording system, and/or
    wherein an automatic command for determining the frequency-resolved curves (34a-c, 44a-c, 54a-c, 60a-m) of a feedback tendency (60) of the hearing device (1) in the first use situation (32) is generated on the basis of the image data generated by the video recording system.
11. A hearing device (1), configured to perform the method according to one of the preceding claims.

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