EP3576433A1 - Method for reduction of acoustic feedback in a hearing aid - Google Patents

Abstract

The invention relates to a method for reducing the occurrence of acoustic feedback in a hearing device (1), wherein a first wearing situation (30) is established which defines a positioning of the hearing device (1) relative to the wearer, whereby for the first wearing situation (30) a first use situation (32) is produced, which is characterized by at least one body movement of the wearer of the hearing aid (1) and / or at least one position of an external object relative to the wearer's body, and wherein a first number is present for the first use situation (32) frequency-resolved curves (34a-c) of a feedback tendency (60) of the hearing aid (1) is determined. It is provided that a first criticality measure (36) is determined based on the or each frequency-resolved curve (34a-c) for the first use situation (32), which contains information about a frequency range (68) that is critical with regard to the occurrence of acoustic feedback and a corresponding one contains relative probability of an acoustic feedback occurring, and the first criticality measure (36) is used to specify (38) an adjustment of at least one hearing aid parameter (40).

Description

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

In the operation of a hearing aid, the occurrence of acoustic feedbacks presents a particular problem. The sound generated by an output transducer of the hearing aid, which is intended for the hearing of the wearer of the hearing aid, propagates in part to an input transducer of the hearing aid, and thereby passes again into the Signal processing of the hearing aid, in which a gain is applied to the signal of the input transducer. In this case, if the attenuation factor by which the sound of the output transducer is attenuated on the sound path to the input transducer is less than the amplification factor of the signal processing, the system may become unstable as a result of the closed amplification loop. This is audible as a whistling sound at the respective frequencies, and therefore leads to a significant impairment of the hearing of the wearer.

One of the common measures for suppressing such acoustic feedback is to reduce the signal processing gain when the feedback is registered. The reduction of the 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 exclusively as a function of the individual hearing impairment of the wearer, so that an output sound signal generated by the output transducer is no longer optimally tuned to the audiological needs of the wearer. It is also possible to suppress the acoustic feedback by means of an adaptive filter by the implementation of an electric feedback loop. As a result, however, artifacts in the output sound signal can arise due to the successful electronic extinction of signal components.

Moreover, the occurrence of acoustic feedback is to a considerable extent tied to the specific situation of use. For example, while feedback may not be expected in normal operation at a given frequency due to the ratio of attenuation in the acoustic feedback path and gain in electronic signal processing, the acoustic feedback path may change with changes such as making a phone call or putting on a headgear be changed, that the attenuation is reduced, and thus it comes to a critical feedback loop. Just such a spontaneous occurrence of feedback often leads in the described measures for suppression to a perceived as unpleasant whistling.

The invention has for its object to provide a method by which a spontaneous occurrence of feedback in certain situations is reduced, which should have the least possible impact on the generated according to the individual hearing impairment of the wearer of the hearing aid based on the input signals.

The above object is achieved by a method for reducing the occurrence of acoustic feedback in a hearing aid, wherein a first wearing situation is established, which defines a positioning of the hearing aid relative to the carrier, wherein for the first wearing situation, a first use situation is produced by at least one body movement the wearer of the hearing device and / or at least one relative position of an external object to the body of the wearer is characterized, and wherein a first number 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 criterion of criticality is determined from the or each frequency-resolved curve for the first use situation, which contains information about a frequency range critical with respect to an occurrence of an acoustic feedback and a corresponding relative probability for occurrence of an acoustic feedback, and with reference to the first Criticalitätsmaßes a default for adjusting at least one hearing aid parameter takes place. Advantageous and partly inventive in themselves embodiments are the subject of the dependent claims and the following description.

A wearing situation here is to be understood in particular as the entirety of the circumstances under which the hearing aid is fixed locally on the wearer, and in particular an optionally present, exchangeable acoustic coupling piece (such as an ear mold piece or a so-called "dome") assumes a specific position , In this respect, two carrying situations may differ with respect to the exact spatial position of the hearing device and / or the acoustic coupling piece, or may be given by the use of different acoustic coupling pieces. In this context, a use situation here and hereinafter includes in particular that the wearer of the hearing device performs body movements during operation, in particular in a given carrying situation, or moves himself relative to limiting objects such as walls or windows, so that the movements taking place in the use situation are particularly suitable are to influence an acoustic Rücckopplungspfad the hearing aid.

A feedback tendency of the hearing aid includes, in particular, a frequency-dependent parameter, by means of which a quantitative probability for an occurrence of acoustic feedback at the relevant frequency can be determined. In particular, a feedback tendency may be given by a ratio or a difference of an attenuation of the acoustic Feedback path and a gain by a hearing aid in the signal processing. A frequency-resolved curve of a feedback slope may be given by the respective values of the feedback slope over the corresponding frequency spectrum, or by the values of the feedback slope at a plurality of nodes for the frequency to be selected, which are to be selected in a sufficiently high frequency resolution.

In this case, in the case of a plurality of frequency-resolved curves for the first use situation, in particular such a curve can be chosen as the first criterion of criticality for which the amplification of the signal processing in the hearing device is greatest in frequency bands compared with the attenuation by the acoustic feedback path. Such a curve can be created in particular from the maximum values over the individual curves at each frequency.

However, for a plurality of frequency resolved curves for the feedback slope, the first criterion of criticality may also be determined by weighting the values of the various curves at a given frequency. In this case, it is preferable to calculate the criticality measure such that at a given frequency for a high variance in values of the feedback slopes of the different curves, a higher value is generated for the first criticality measure than in a situation with an identical maximum value of the feedback slopes at 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 slope in the first use situation, a further spread beyond the decimal value detected in the measurement is to be expected, while a small 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 slope as well as the variation over the various curves at a given frequency, the risk of feedback occurring at the corresponding frequency for the first usage situation may be inferred. The relative probability of a Such an occurrence of the feedback can in this case also be related to other frequency ranges, ie the first criterion of criticality in particular to the effect that a feedback for a first frequency is then more probable than for a second frequency if the value of the first criterion of criticality at the first frequency is greater than the value at the second frequency.

Preferably, the at least one hearing aid parameter is adjusted in accordance with the specification made on the basis of the first criterion of criticality, wherein the adaptation can be effected in particular automatically. Alternatively, the adjustment according to the specification can also be followed manually by a hearing care professional. In this case, the at least one hearing aid parameter is preferably adjusted under the additional specification to impair as little as possible a signal amplification and a playback dynamics in the hearing aid. This can be done, in particular, by adapting the at least one hearing aid parameter only for that frequency range for which, based on the first criterion of criticality, an occurrence of a feedback in the first use situation is considered to be sufficiently probable. The evaluation can be carried out by a threshold value comparison of the frequency-resolved first criterion of criticality over the entire spectrum.

By adapting the at least one hearing device parameter on the basis of the first criterion of criticality, on the one hand, the probability of an occurrence of feedback can thus be limited purposefully to those frequency ranges in which a change of the present hearing aid parameters to avoid feedback is even necessary, whereby the adaptation with regard to the reproduction properties of the hearing aid "minimally invasive" can be configured. Previous methods of reducing or suppressing feedback based on adaptation of hearing aid parameters typically check the occurrence of feedbacks frequency band wise. The adaptation of the hearing aid parameters for the signals involved takes place with the least possible time delay for their verification, since it takes place during the ongoing operation of the hearing aid. This is to Only a limited number of frequency bands are available at the level of the check, since otherwise the filters used to divide an input signal into different frequency bands would require too high a latency. On the other hand, the hearing aid parameters are set frequency-bandwise at the level of the adaptation, whereby the reproduction for the entire frequency band is affected, for example, with a reduction of a gain in a frequency band, while possibly only for a narrow frequency interval within this frequency band, a critical probability for occurrence of a Feedback exists, and thus an adjustment of the gain would be sufficient only over this interval.

On the other hand, it can be checked on the basis of the first criterion of criticality and on the basis of the described adaptation whether a probability of a feedback for the first feedback situation can actually be reduced by the corresponding adaptation of the at least one hearing aid parameter. Should this not be the case, this can be regarded as an indication of a problem, which is related in the broadest sense with the wearing situation of the hearing aid, and accordingly, further measures can be adjusted to this.

Preferably, for the first usage situation, a plurality of frequency-resolved feedback slope curves are determined, wherein at a given frequency, the first criticality measure for the first user situation is formed based on a measure of the spread of the plurality of frequency resolved waveforms of the feedback slope at that frequency. In particular, in this case the first use situation is continuously maintained, for example by maintaining and / or repeating a corresponding body movement. Concretely, this can be done in such a way that the body movement, by which the first usage situation is characterized, is repeated several times, and a plurality of curves of the feedback tendency are thereby determined. This can be done over a predetermined period of time, or until a predetermined amount of readings and / or curves for the feedback slope have been determined in sufficient quality of measurement. Subsequently For each frequency, the scattering measure, eg the variance of the values which the different curves for the feedback slope have at this frequency, is calculated, and the first criterion of criticality is formed on the basis of the determined variances for different frequencies.

By using a spread measure which gives an indication of how the values of the feedback slope may differ over the first usage situation at a given frequency, those frequency ranges in which the feedback slope is exceeded over the values determined in the present curves can be identified and, accordingly, the at least one hearing aid parameter may be adjusted even if, for a given frequency, none of the determined values for the feedback slope are immediately critical to feedback. Thus, for a given frequency, the degree of scattering of the values of the feedback slope can be considered as an indicator of the stability of the feedback path in the first use situation. With a low value of the scattering measure, it is assumed that the values in real operation of the hearing aid only slightly exceed the determined range of values for the given frequency when reproducing the first usage situation, whereby the adaptation of the at least one hearing aid parameter can be further restricted has a positive effect on the playback characteristics of the hearing aid.

Advantageously, an attenuation of an acoustic feedback path is measured, wherein the feedback tendency to a given frequency is 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, at a given frequency, the feedback slope is determined as a sum or product of the attenuation of the acoustic feedback path and the signal gain in the hearing aid. The attenuation of the acoustic feedback path can in this case be determined in particular by means of an adaptive filter, or be measured directly by means of a modulated test signal.

It proves to be advantageous if the first situation of use is established by the wearing of a headgear by the wearer, and / or a jaw movement of the wearer, and / or the use of a mobile telephone in the vicinity of the hearing aid by the wearer, and / or a sporty one Actuation of the carrier, and / or positioning of the carrier in the immediate vicinity of a spatial boundary. In particular, a hat, a cap, and a headscarf are included as a headgear. In particular, the jaw movement may consist of chewing or speaking. Under a spatial boundary here in particular a window and a wall are included. The positioning is not bound to the movement process, but it can be turned off especially on a purely static situation in the vicinity of the boundary. In particular, for the existence of the first use situation, a cumulative existence of said conditions is possible, for example, by having a head covering sold off for an incipient telephone conversation. The possibilities mentioned for the first situation of use cover a broad spectrum of situations which 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 a total gain at a frequency, and / or a compression characteristic at a frequency, and / or a readjustment speed. The compression characteristic at a frequency is defined here in particular by a compression ratio and a knee point. In particular, the total gain at a frequency may also include an immediately surrounding frequency interval. If the first criterion of criticality is determined essentially continuously over the frequency, then critical frequencies usually do not arise in isolation with respect to a probability for acoustic feedback - since at such a frequency the first criterion of criticality would have to assume its critical value exactly as the point of contact - but over an interval of frequencies. As the at least one hearing aid parameter, it is then possible to adapt the overall gain or the compression characteristic in this interval, or also a readjustment speed of the adaptive filter. The mentioned hearing aid parameters are on the one hand suitable to suppress an acoustic feedback by appropriate adjustment. On the other hand, their adaptation in the hearing aid is technically possible without additional effort, so that there is no unnecessary burden on the signal processing.
A second usage situation is preferably produced for the first wearing situation, wherein a second criterion of criticality is determined for the second usage situation, wherein a specification for adjusting the at least one hearing aid parameter and / or a further hearing aid parameter takes place on the basis of the second criterion. In particular, in this case the second criterion of criticality for the second usage situation is determined in an analogous manner as the first criterion of criticality for the first usage situation. This makes it possible to individually evaluate the probability of an occurrence of feedback for different processes, and to specify the adaptation of one or more hearing device parameters depending on the totality of the evaluations. In this case, the second use situation is particularly preferably produced by one of the operations mentioned for the first use situation.

In a further advantageous embodiment, the at least one hearing aid parameter is adjusted according to the specification made on the basis of the first criterion of criticality, wherein the hearing aid is operated with the adapted hearing aid parameter in a test operation, wherein the first use situation is established in test operation, and wherein for the first use situation in test operation a third criterion of criticality for, in particular, automatic verification of the adaptation is determined. The third criterion of criticality is preferably determined in the manner described above, that is to say in a manner analogous to the first criterion of criticality, thereby ensuring comparability of the values at a given frequency. In particular, the test operation can also consist in a resumption of the regular operation of the hearing aid, wherein first said by means of the third Kritikalitätsmaßes said review of the adjusted based on the first criterion of criticality Hörgeräteparameters, and the regular operation in the case of a positive review of the review is simply continued, and Case of a negative review of the review further action will be proposed. However, the test operation can also be done by an independent routine be formed. In this case, the first situation of use is established in the context of the said routine, and by means of the third criterion of criticality the present setting of the hearing aid is checked, which comprises the adaptation of the at least one hearing aid parameter made on the basis of the first criterion of criticality.

It proves to be further advantageous if a second wearing situation is established, wherein the first use situation is established for the second wearing situation, wherein a fourth criticality measure is determined for the first use situation in the second wearing situation, and wherein with reference to the fourth criterion of criticality a specification with respect to a suitability of the second carrying situation for the operation of the hearing aid takes place. The fourth criterion of criticality is preferably determined in the manner described above, that is to say in a manner analogous to the first measure of criticality and particularly preferably also to the third criterion of criticality, thereby making it possible to compare the values of the first measure of criticality and at least the fourth measure of criticality, particularly preferably of the third criterion of criticality at a given frequency is ensured. The production of a second carrying situation can be advantageous, in particular, if the probability of the occurrence of a feedback in the first use situation can not be significantly reduced by adapting the hearing device parameters, and this is determined in particular by checking the adaptation by means of the third criterion of criticality.

For example, on the basis of the first criterion of criticality, a specification can be made for changing the at least one hearing aid parameter, and this can be adapted accordingly under the secondary conditions which result from the requirement for the reproduction dynamics and volume for the wearer. Subsequently, the first usage situation is established in the test mode, and the third criticality measure for the adjusted settings is determined here. If now it is found that feedback is still critically probable even after a successful adaptation of the settings, preferably within the audiologically acceptable framework, this is considered to be an indication of an im the broadest sense of the mechanical problem, which can therefore be remedied by changing the wearing situation.

On the basis of the fourth criterion of criticality is now checked in particular whether the already in the first step - based on the first Critikalitätsmaßes - adapted settings for a regular operation of the hearing aid in the second wearing situation, ie in particular the probability of feedback - according to the Criticality measures used as a criterion - significantly reduced compared to the first wearing situation. Preferably, therefore, based on the fourth criterion of criticality, a specification with regard to a suitability of the second wearing situation for the operation of the hearing aid with the at least one hearing aid parameter adjusted on the basis of the first criterion of criticality is carried out

Advantageously, the second carrying situation is produced by a position correction of an acoustic coupling piece of the hearing aid, and / or a use of an acoustic coupling piece with changed dimensions, and / or a use of an acoustic coupling piece with a modified ventilation opening. In this case, an ear coupling, a so-called "dome" and a so-called "ear mold" are in particular included under an acoustic coupling piece. On the one hand, acoustic feedbacks through the use of another acoustic coupling piece are particularly efficient in correcting that these can usually be replaced simply and without great expertise - that is to say, the measures mentioned are frequently sources of error when the hearing device is put into its regular carrying position by the wearer himself or a trusted person, without requiring a visit to a hearing care professional - and no further, more complex interventions on the hearing aid are required. Against this background, the first wearing situation is produced in particular by a simple application of the hearing aid - according to the present mechanical configuration - in the supposed wearing position.

Conveniently, at least the first carrying situation and the first use situation are detected by means of a video recording system. A capture In this case, a video recording system can in particular make it possible for visiting a specialist, eg a hearing aid acoustician, to avoid having to reduce the probability of feedback, which proves to be comfortable for the wearer.

It proves to be further advantageous if image data generated by the video recording system are transmitted to and reproduced by a video playback system spatially separated from the carrier, and / or an automatic command for determining the number of frequency-resolved curves of a feedback tendency of the video data system generated by the video recording system Hearing aid is generated in the first use situation. In this case, the automatic command can be generated in particular on the basis of a face or generally an image recognition, which determines the correct production of the first use situation, e.g. by detecting a chewing or speaking movement of the jaw or the introduction of a mobile phone to the ear by the wearer.

For example, the video display system may be located at a hearing care professional in its work spaces while the wearer is at home in the detection area of the video recording system. In response to a start signal from the hearing device auditor to which the determination of the tendency to feedback should also begin, the wearer produces the first usage situation in the first wearing situation, eg by putting on a headgear or by guiding a mobile phone to his ear. The first use situation can now be terminated on the one hand by the expiration of a fixed period of time, or on the other hand be terminated if 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 then determined from the determined curves of the feedback tendency. Based on the first Critikalitätsmaßes now an adjustment of the at least one hearing aid parameter is given. The adaptation itself can be done either by the wearer himself, by a trusted person of the wearer (in particular, if this even unable to do this) or via a suitable remote access by the hearing care professional.

Once the adaptation has been carried out, the first use situation in the test mode can now be produced again on a further start signal, and further curves of the feedback tendency can be determined, from which the third criterion of criticality is then determined. Based on the third criterion of criticality, it is now checked whether the adjustment of the settings has sufficiently reduced the feedback tendency. If this is not the case, then the hearing aid acoustician can instruct the wearer to produce the second wearing situation, where appropriate the concrete selection of the measure based on the third and possibly also on the basis of the first criterion of criticality - e.g. About characteristic for certain errors gradients -wird and can be specified in particular automatically. If, as the second wearing situation, a measure is specified which the wearer can not perform independently, his trusted person can, under the direction of the hearing aid acoustician, establish the second wearing situation via the video surveillance system.

Now, in the manner described above, the first usage situation is established in response to a start signal, and a renewed series of measurements of the feedback tendency for determining the fourth criterion of criticality is carried out, on the basis of which the suitability of the second carrying situation for suppressing the feedback is evaluated.

The invention further mentions a hearing device which is set up to carry out the method described above. In particular, in this case the hearing device 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 device preferably also has means for transmitting a signal amplification as well as the attenuation due to the acoustic feedback to an external detection unit. In this case, parts of the above-described method, such as determining the first and further criticality measures and the corresponding presets in the external detection unit, can take place. alternative For this purpose, the hearing device 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 embodiment of the invention will be explained in more detail with reference to a drawing. Here are shown schematically in each case:

• Fig. 1 in a block diagram a hearing aid in which an acoustic feedback occurs,
• Fig. 2 1 is a block diagram of a method for reducing a backtack 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 slopes for different usage situations and a resulting criterion of criticality.

Corresponding parts and sizes are provided in all figures with the same reference numerals.

In FIG. 1 is shown schematically in a block diagram of a hearing aid 1. An input transducer 2 of the hearing aid 1, which is configured here as a microphone, converts a sound signal 4 of the environment into an input signal 6. The input signal 6 is supplied in the hearing aid 1 a signal processing 8 and processed there according to the audiological needs of the wearer of the hearing aid 1 and in this case in particular amplified frequency band dependent. The resulting from the signal processing 8 output signal 10 is converted by an output transducer 12 of the hearing aid 1 into an output sound signal 14, which is performed to the hearing of the wearer of the hearing aid 1, not shown. The output transducer 14 is presently given by a loudspeaker, which is arranged in an acoustic coupling piece 15 of the hearing device 1. The acoustic coupling piece is given here as an earmold. Along an acoustic feedback path 16, a portion of the output sound signal 14 can now go again to the input converter 2, and thus find input into the input signal 6, whereby a closed feedback loop is formed, in which signal components are amplified by the signal processing 8 more and more.

To suppress the acoustic feedback occurring, the amplification can now be reduced on the one hand in the signal processing 8. However, this is associated with a loss of gain also for other signal components not affected by the acoustic feedback, so that the signal processing 8 no longer operates 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 even 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 supplied to the input signal 6 and subtracted from this. On the one hand, the signal resulting from this subtraction is input into the signal processing 8, and on the other hand is also supplied to the adaptive filter as an error signal 22. In particular, the acoustic feedback path 16 or its frequency response is estimated in the adaptive filter 18.

However, situations may also occur in which the subtraction of the compensation signal 20 from the input signal 6 leads to undesirable effects such as artifacts in the output signal 10. The rate at which the estimate of the feedback path is updated forms as a variable time parameter of the adaptive filter 18. The shorter this time parameter is set, the faster the suppression of feedback adapts to a change in the acoustic feedback path. However, the quicker readjustment by the user can all the more frequently be perceived as a disturbing artifact. In this respect, a trade-off should be chosen here for a pleasant sense of sound, preferably without feedback.

Moreover, the occurrence of an acoustic feedback sometimes also predominantly mechanical causes, such as a non-optimal fit of the acoustic coupling piece 15 of the hearing aid 1 in the ear of the wearer, whereby a particularly high proportion of the output sound signal 14 escape and can get back to the input transducer 2. Other causes, which may be described as mechanical, may depend on a specific situation of use such as, for example, a chewing or speaking movement or the influence of the acoustic feedback path 16 by a mobile telephone or other similar object in the vicinity of the hearing aid 1. In this case, on the one hand, the suppression of the feedback by the adaptive filter 18 is not always expedient under the risk of artifacts in the output signal 10. On the other hand, it can be useful or desirable to impede the acoustic feedback occurring as a function of the specific situation of use in advance, without restricting the reproduction of the hearing aid 1 significantly in its dynamics.

This is in FIG. 2 shown in a block diagram, which has a corresponding method to the subject. First, a first carrying situation 30 is produced, in which the wearer after the hearing aid 1 FIG. 1 regular. The first wearing situation 30 is characterized in particular by the global position of the hearing aid 1 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 carrier. In the first carrying situation 30, a first use situation 32 is now produced, which is characterized by at least one body movement of the carrier and / or by an external object. This can be done for example by putting on a headgear such as a hat or a cap, by a jaw movement of the wearer when talking or chewing or by the use of a mobile phone in the vicinity of the hearing aid. During the first usage situation, a plurality of frequency-resolved waveforms 34a-c of a feedback slope of the hearing aid are determined. This is done by, for example, by repeating the movement, which of the first usage situations the measurement process is repeated for the feedback slope, and over time a plurality of "screenshots" of the feedback slope over the frequency is generated. From the frequency-resolved curves 34a-c of the feedback tendency, a first criticality measure 36 is generated in a manner to be described, on the basis of which a default 38 is made for adapting at least one hearing device parameter.

In an analogous manner, which is not shown in detail, a second usage situation can also be established in the first carrying situation 30, in which frequency-resolved curves of a feedback tendency of the hearing aid 1 are also detected FIG. 1 are determined from which a second criterion of criticality is determined. On the basis of the second criterion of criticality determined in this way, it is then also possible to specify one or more hearing aid parameters, wherein the specification can relate to the hearing aid parameter or parameters for which a specification 38 is already made on the basis of the first criterion of criticality 36. On the other hand, the prescription prepared on the basis of the second criterion of criticality may also relate to other hearing aid parameters for which no prescription exists yet.

According to the specification 38 and, if appropriate, according to a further specification created in a second situation of use, the hearing device parameter 40 is now adapted. The hearing aid parameter 40 can be, for example, an overall gain at a specific frequency, and / or a compression characteristic at a specific frequency, but also a parameter of the adaptive filter 18 FIG. 1 , For example, a Nachregelungsgeschwindigkeit or a step size. Now, a test operation 42 is recorded, in which the hearing aid 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 therefore generated while the movement corresponding to the first usage situation is repeated in the test mode 42. From the frequency-resolved curves 44a-c, a third criterion of criticality 46 is generated analogously to the first criterion of criticality 36. Based on the third Critikalitätsmaßes 46 can now it is determined whether the adaptation of the hearing aid parameter 40 according to the specification 38 has significantly reduced the probability of an occurrence of an acoustic feedback during the first use situation 32.

If this is not the case, then a second carrying situation 50 is proposed. This may be, for example, a position correction of the acoustic coupling piece 15 of the hearing aid 1, or a use of an acoustic coupling piece with changed dimensions and / or a modified ventilation openings. After the corresponding measure, which characterizes the second carrying situation 50, has been proposed, which can take place in particular automatically, the wearer of the hearing device 1 or a person of trust produces the second wearing situation. Subsequently, for the second carrying situation 50, the first usage situation is again produced by the corresponding movement. Once again frequency-resolved curves 54a-c for the feedback slope are determined, on the basis of which a fourth criticality measure 56 is determined. Based on the fourth criterion of criticality 56 can now be checked whether according to the first criterion of criticality 36 default for the adjustment of the hearing aid 40 in the second situation 50 is suitable for keeping the probability of the occurrence of an acoustic feedback sufficiently low. If this is the case, then 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 optionally exchanged acoustic coupling piece, or by continuously ensuring that it fits properly in the case of the application of the acoustic coupling piece Auditory canal penetrates. If the fourth criticality measure 56 does not suggest a substantial improvement in the feedback tendency, then a third carrying situation (not shown in detail) can be produced analogously to the second carrying situation 50, or the search for a hearing aid acoustician can be recommended as a "last resource" measure.

In FIG. 3 For example, in a graph, a feedback slope 60 in dB versus frequency f is plotted. The feedback slope 60, which is a measure of a probability of occurrence of acoustic feedback, is formed here by the damping 62 of the acoustic feedback path 16 after FIG. 1 (dashed line) which takes place in the signal processing 8 gain 64 (dash-dotted line) is added.

In FIG. 4 For example, a plurality of frequency-resolved curves 60a-m for the feedback tendency are shown. These correspond, for example, different individual measurements, which during the first use situation after FIG. 2 be performed. While in the frequency range up to about 3 kHz the individual curves 60a-m barely differ from each other, and thus the variance of the different curve values at a given frequency is hardly noticeable, the curves 60a-m drift apart noticeably from 3 kHz upwards. In particular, a narrow frequency range around 6 kHz should be mentioned, in which the individual curves differ in their values by up to 30 dB. From 7 kHz upwards, the course of the curves is almost uniform again.

Based on the curves 60a-m, a criticality measure 66 is now determined analogously to the first criterion of criticality 36, the third criterion of criticality 64, and the fourth criterion of criticality 56. This is done by adding at each frequency f to the maximum value 60m for the feedback slope (dotted line) a correction term that is monotonically dependent on the variance of the individual values of the curves 60a-m for a given frequency f. Thus, for the high variance, which is just below 6 kHz, the criticality measure 66 (dashed line) is maximal.

While the absolute values of the individual curves 60a-m are even higher in the range around 2 kHz than the maximum value 60m at approximately 4 kHz, the criticality measure 66 is larger there than at 2 kHz due to the higher variance at 4 kHz. This takes into account the fact that over the entire range of possible values during the first use situation at 2 kHz a higher stability of the system is present than at 4 kHz, therefore it can be assumed that at 4 kHz the maximum value determined is not necessarily the absolute possible Maximum value, while this is probably the case because of the high stability at 2 kHz. Accordingly, the criticality measure is higher at 4 kHz.

It is now possible to identify from the criterion of criticality 66 frequency ranges 68 for which the occurrence of acoustic feedback in the respective situation of use is particularly probable and must be adapted in accordance with a hearing aid parameter. For this purpose, the exceeding of a threshold value by the criterion of criticality 66 can be used as a criterion, with a threshold value in the first approximation 0 dB, ie the limit for a critical amplification, being selected

Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by this embodiment. Other variations can be deduced therefrom by those skilled in the art without departing from the scope of the invention.

LIST OF REFERENCE NUMBERS

1

hearing Aid

2

input transducer

4

sound signal

6

input

8th

signal processing

10

output

12

output transducer

14

Output sound signal

15

acoustic coupling piece

16

acoustic feedback path

18

adaptive filter

20

compensation signal

22

error signal

30

first carrying situation

32

first use situation

34a-c

frequency resolved curves

36

first criterion of criticality

38

specification

40

hearing aid parameters

42

test mode

44a-c

frequency resolved curves

46

third criterion of criticality

50

second carrying situation

54a-c

frequency resolved curves

56

fourth criterion of criticality

60

Feedback risk

60a-m

frequency resolved curves (for feedback slope)

60m

maximum value

62

damping

64

reinforcement

66

Kritikalitätsmaß

68

frequency range

Claims (13)

Method for reducing the occurrence of acoustic feedback in a hearing aid (1),
wherein a first wearing situation (30) is established, which defines a positioning of the hearing aid (1) relative to the wearer,
wherein for the first wearing situation (30) a first use situation (32) is produced which is characterized by at least one body movement of the wearer of the hearing aid (1) and / or at least one relative position of an external object to the body of the wearer,
wherein for the first use situation (32) a first number of frequency-resolved curves (34a-c) of a feedback tendency (60) of the hearing aid (1) is determined,
wherein a first criterion of criticality (36) is determined from the or each frequency-resolved curve (34a-c) for the first use situation (32), which contains information about a frequency range (68) critical with respect to occurrence of an acoustic feedback and a corresponding relative probability Occurs an acoustic feedback, and wherein based on the first criterion of criticality (36) is a default (38) for adjusting at least one hearing aid parameter (40). Method according to claim 1,
wherein a plurality of frequency resolved curves (34-c) of a feedback slope (60) is determined for the first usage situation (32), and
wherein at a given frequency, the first criticality measure (36) for the first user situation (32) is formed based on a spread measure for the respective values of the feedback slope (60) resulting from the plurality of frequency resolved curves (34a-c) at that frequency. A method according to claim 1 or claim 2,
wherein an attenuation (62) of an acoustic feedback path (16) is measured, and
wherein the feedback slope (60) at a given frequency is determined in each case from a signal amplification in the hearing aid (1) and from the attenuation (62) of the acoustic feedback path (16). Method according to one of the preceding claims,
wherein the first use situation (32) is established by - The putting on of a headgear by the wearer, and / or a jaw movement of the wearer, and / or - The use of a mobile phone in the vicinity of the hearing aid (1) by the wearer, and / or - a sporting activity of the wearer, and / or - A positioning of the carrier in the immediate vicinity of a spatial boundary. Method according to one of the preceding claims,
wherein the at least one hearing aid parameter (40) is selected from a total gain at one frequency, and / or a compression characteristic at a frequency, and / or - a readjustment speed. Method according to one of the preceding claims,
wherein a second usage situation is established for the first carrying situation (30),
wherein a second criterion of criticality is determined for the second situation of use, and
wherein based on the second Critikalitätsmaßes a default for adjusting the at least one hearing aid parameter (40) and / or a further hearing aid parameter takes place. Method according to one of the preceding claims,
wherein the at least one hearing device parameter (40) is adapted according to the specification (38) made on the basis of the first criterion of criticality (36),
wherein the hearing aid (1) is operated with the adapted hearing aid parameter (40) in a test operation (42),
wherein in the test mode (42) the first use situation (32) is established, and wherein for the first use situation (32) in the test mode a third criterion of criticality (46) for checking the adaptation is determined. Method according to one of the preceding claims,
wherein a second carrying situation (50) is produced,
wherein for the second carrying situation (50) the first use situation (32) is produced,
wherein for the first use situation (32) in the second carrying situation (50) a fourth criterion of criticality (56) is determined, and
wherein on the basis of the fourth criterion of criticality (56) a specification regarding a suitability of the second carrying situation (50) for the operation of the hearing aid (1). Method according to claim 7 and claim 8,
wherein on the basis of the fourth criticality measure (56) a specification with regard to suitability of the second carrying situation (50) for the operation of the hearing aid (1) with the at least one hearing aid parameter (40) adapted on the basis of the first criterion of criticality (36). Method according to claim 8 or claim 9,
wherein the second carrying situation (50) is produced by - A position correction of an acoustic coupling piece (15) of the hearing aid (1), and / or a use of an acoustic coupling piece (15) with changed dimensions, and / or - Use of an acoustic coupling piece (15) with a modified ventilation opening. Method according to one of the preceding claims,
wherein at least the first carrying situation (30) and the first use situation (32) are detected by means of a video recording system. Method according to claim 11,
wherein image data generated by the video recording system is transmitted to and reproduced from a video playback system spatially separated from the carrier, and / or
wherein an automatic command for determining the number of frequency-resolved curves (34a-c, 44a-c, 54a-c, 60a-m) of a feedback tendency (60) of the hearing aid (1) in the first use situation (FIG. 32) is generated. Hearing aid (1), which is set up for carrying out the method according to one of the preceding claims.

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