EP3393143A1 - Method for operating a hearing aid - Google Patents

Abstract

The invention relates to a method (20) for operating a hearing device, wherein a first direction-dependent signal (8f) and a second direction-dependent signal (8r) are generated in the hearing device from a sound signal (22) of the environment, and wherein, based on the first direction-dependent signal ( 8f) and the second direction-dependent signal (8r), a first adaptation coefficient (α1) for a first superimposition (30) of the first direction-dependent signal (8f) with the second direction-dependent signal (8r) for noise suppression determined with a first reaction time (t1) becomes. In this case, it is provided that a second adaptation coefficient (α2) for a second superimposition (32) of the first direction-dependent signal (8f) with the second direction-dependent signal (8r) is used for the first direction-dependent signal (8f) and the second direction-dependent signal (8r) Noise suppression with a second reaction time (t2) is determined, and on the basis of the first adaptation coefficient (α1) and the second adaptation coefficient (α2) an output adaptation coefficient (a-out) to form an output signal (42) by an overlay of the first direction-dependent Signal (8f) and the second directional signal (8r) is determined.

Description

The invention relates to a method for operating a hearing aid, wherein a first direction-dependent signal and a second direction-dependent signal are generated in the hearing aid from the ambient, wherein on the basis of the first direction-dependent signal and the second direction-dependent signal, an adaptation coefficient for a superposition of the first direction-dependent signal is determined with the second direction-dependent signal for noise suppression, and wherein an output signal is formed by an overlay of the first direction-dependent signal with the second direction-dependent signal.

In hearing aids, one of the most common problems is to improve the signal-to-noise ratio (SNR) for certain listening situations. This is often achieved using directional signal processing algorithms. In this case, it is often assumed that a strongly localized wanted signal component is present in the sound signal of the environment which enters the hearing aid, for example in the form of conversation contributions by a conversation partner. This useful signal component is now delimited by means of direction-dependent signals in the hearing device with respect to a background assumed to be a noise signal, although the noise signal may also have a significant directional dependence. In general, the algorithms mentioned often use self-optimization, wherein the directional characteristic of a direction-dependent signal is adapted in such a way that the influence of interference signals from the direction in which their contribution is greatest is minimized. This is usually done by minimizing the signal power of a corresponding directional signal.

In a first order differential directional microphone with only one adaptation coefficient, a directional output is often achieved by a linear combination of a forward cardioid with a backward cardioid. A change in the directional characteristic can be achieved via the adaptation coefficient, which determines the contribution of the backward cardioid. As a result, the contributions of noise sources, which may be in a wide solid angle range with respect to the forward direction of the hearing aid, can be reduced. However, this does not apply to a noise source which is positioned in the forward direction and thus in the "notch" of the backward cardioid.

For a stationary noise source positioned in the posterior hemisphere and a simultaneous non-stationary payload source in the anterior hemisphere (out of the "notch" of the backward cardioid), an algorithm for adapting the directional signal to the listening situation must have different contributions from both Consider sound sources for signal power. If the non-stationary signal of the useful signal source has a sufficiently high SNR, the adaptation coefficient varies with the signal power of the useful signal. As a result, however, the attenuation of the stationary noise can be affected, so that in the output signal, the actually stationary noise as a fluctuating depending on the presence of the non-stationary useful signal with noise received (co-modulation). If the useful signal is a voice signal, speech quality can be impaired in addition to the voice quality.

The invention is therefore based on the object of specifying a method for operating a hearing device, by means of which a stationary noise can be suppressed with the least possible interference by a non-stationary useful signal.

The above object is achieved by a method for operating a hearing aid, wherein in the hearing aid from a sound signal of the environment a first direction-dependent signal and a second direction-dependent signal are generated, wherein based on the first direction-dependent signal and the second direction-dependent signal, a first adaptation coefficient for a first superimposition of the first direction-dependent signal with the second direction-dependent signal for noise suppression is determined with a first reaction time, and wherein, based on the first direction-dependent signal and the second direction-dependent signal, a second adaptation coefficient for a second superimposition of the first direction-dependent signal with the second direction-dependent signal for noise suppression is determined with a second reaction time. In this case, it is provided that, on the basis of the first adaptation coefficient and the second adaptation coefficient, an output adaptation coefficient for forming an output signal is determined by superposition of the first direction-dependent signal and the second direction-dependent signal. Advantageous and partly inventive in themselves embodiments are the subject of the dependent claims and the following description.

In this case, a first direction-dependent signal or a second direction-dependent signal is understood in particular to be an electrical signal which, for a given test sound signal having a constant sound pressure and thus a fixed volume, has a sensitivity which depends on the direction of the sound source of the test sound signal. This means, in particular, that a spatial direction exists in which the test sound signal leads to a maximum signal level in the first or second direction-dependent signal, and that at least one further spatial direction exists, for which the test sound signal leads to a minimum signal level in the corresponding direction-dependent signal. The spatial directions of maximum and minimum sensitivity of the first direction-dependent signal differ from the spatial directions of maximum and minimum sensitivity of the second direction-dependent signal. In this case, the first direction-dependent signal and the second direction-dependent signal are preferably designed such that their directions of maximum and minimum sensitivity to each other are arranged in mirror image, and thus the direction of maximum sensitivity for the first directional signal coincides with the direction of minimum sensitivity of the second directional signal and vice versa. Particularly preferably, a sound signal is completely suppressed in the direction of minimum sensitivity of the first and / or the second direction-dependent signal, so that according to the first and / or second direction-dependent signal, a sound signal from the direction of the respective minimum sensitivity provides no level contribution.

The first superimposition and / or the second superposition here are preferably of the form F + α * B, where F and B denote the first and second direction-dependent signals, respectively, and α the first and second adaptation coefficients, respectively. The first and second adaptation coefficients thus indicate the degree of the proportion of the second direction-dependent signal in the first and second superimposition. The determination of the first adaptation coefficient and of the second adaptation coefficient can in this case be repeated at predetermined time intervals, as a result of which the first and second adaptation coefficients are respectively updated. The time intervals for these updates are given by first or second reaction time. This has, in particular, the consequence that a change in the sound signal occurring at a certain point in time can in each case only affect the respective adaptation coefficient at the next update with the corresponding reaction time.

The first adaptation coefficient is in this case determined such that a noise, in particular a non-stationary noise, is particularly efficiently suppressed by the corresponding first superimposition of the first direction-dependent signal with the second direction-dependent signal. For this purpose, it is now assumed that a sound source of a useful signal is in the direction of maximum sensitivity of the first direction-dependent signal. Noise, in particular non-stationary, which now reach the hearing device from another spatial direction, can then be suppressed by the first superposition due to the different directional characteristic of the second direction-dependent signal than the first direction-dependent signal. In the event that the direction of maximum sensitivity of the first directional signal with the direction of minimum sensitivity of the second directional signal coincides, can be used as a criterion for the most efficient suppression of noise that does not come from the direction of the maximum sensitivity of the first directional signal, in particular the minimum total power resulting from the first superposition signal. The same applies to the second overlay. Advantageously, the direction of maximum sensitivity of the first direction-dependent signal during intended wearing of the hearing aid is in the frontal direction of the user of the hearing aid.

The first reaction time can now be selected such that the first superposition with the first adaptation coefficient reacts sufficiently fast to non-stationary noise, and thus the first adaptation coefficient is particularly suitable for suppression of this noise. By means of a suitable choice of the second reaction time, it can now be achieved that the second superimposition with the second adaptation coefficient suppresses particularly stationary interference noise, while the second superposition reacts more slowly to considerably non-stationary interference noises. For this purpose, the second reaction time can be statically selected to be greater than the first reaction time by a predetermined factor, or can also be determined dynamically as a function of the first and the second direction-dependent signal. In this case, it is particularly the case that, if the presence of a significantly non-stationary noise component is detected on the basis of the first and the second direction-dependent signal, an update of the second adaptation coefficient is suspended until the end of this non-stationary noise component. Thus, the second response time is dependent on the duration of the non-stationary noise component.

In particular, in this case the first superimposition and the second superposition are formed to determine the first adaptation coefficient and the second adaptation coefficient with the corresponding reaction times, without, however, generating a respective output signal which would be further processed in the hearing aid in some way. Such a further to be used Signal for the signal processing in the hearing aid, however, represents the output signal, which is formed by a superposition of the first direction-dependent signal and the second direction-dependent signal on the basis of the output adaptation coefficient. The output adaptation coefficient is in this case formed on the basis of the first adaptation coefficient and the second adaptation coefficient in such a way that the output resulting from the superimposition according to the output adaptation coefficient has sufficient suppression of non-stationary noise components on the one hand owing to the at least indirect dependence on the first adaptation coefficient is reduced by the corresponding, at least indirect dependence on the second adaptation coefficient, the co-modulation stationary noise components.

If in this case the first adaptation coefficient is determined in such a way that the first superimposition of non-stationary noise components is optimally suppressed, the deviation of the output adaptation coefficient from the first adaptation coefficient is less than optimal in terms of non-stationary noise components. Due to the proportion of the second adaptation coefficient on the output adaptation coefficient reduced co-modulation of stationary noise components, ie in particular by a reduced increase of a noise background during the activated by means of the first adaptation coefficient suppression of non-stationary noise components, thereby an improvement of SNR, which improves the overall hearing and speech intelligibility in particular.

Advantageously, the second reaction time is greater than the first reaction time. In particular, the second reaction time is at least a factor of 2 greater than the first reaction time. In this way it can be ensured that, in the case of a non-stationary noise, the first adaptation coefficient is initially adjusted in the sound signal. In the event that the second reaction time is determined dynamically, the difference remaining between the second reaction time and the first reaction time still leaves sufficient time for the required signal processing processes for such a dynamic adaptation. In the case that the second reaction time is not determined dynamically, but is statically fixed, the second reaction time, in particular by a factor of 4 to 64 may be greater than the first reaction time.

The second reaction time is advantageously determined for determining the second adaptation coefficient as a function of the first direction-dependent signal and the second direction-dependent signal. In particular, this means that on the basis of the first direction-dependent signal and the second direction-dependent signal, a presence of a non-stationary interference signal components in the sound signal of the environment is determined, and the second reaction time is set in dependence on the presence of such a noise component. In particular, in the case of a detected presence of a non-stationary noise component, the second reaction time can be adjusted dynamically to a determined end of this noise component. This means, in particular, that an update of the second adaptation coefficient is initially suspended in the case of a determined presence of said noise component until an end of the noise component is determined on the basis of the first direction-dependent signal and the second direction-dependent signal. Only then is an update of the second adaptation coefficient resumed. In this way it can be ensured that the second adaptation coefficient is not influenced by non-stationary noise components, and the corresponding second interference is essentially only effective for noise suppression of stationary noise. In particular, while the updating of the second adaptation coefficient is suspended, the last current value for the second adaptation coefficient may continue to be used until a renewed updating.

It proves to be advantageous in this case if the second reaction time for determining the second adaptation coefficient is determined on the basis of a difference between the signal power and a background noise power for the first direction-dependent signal and / or based on a difference between the signal power and a background noise power for the second direction-dependent signal. As a noise floor power of the first and second directional signal is in particular, to understand the signal power of a noise floor, which was determined in a separate estimation process. In particular, the background noise is assumed to be essentially stationary, so that non-stationary noise components do not make any appreciable contribution to the respective background noise within the framework of the relevant time scales. In this case, a non-stationary noise provides a significant contribution to the signal power, but not to the noise floor power in one of the two directional signals. By comparing the difference between signal power and noise floor power for the first directional signal with the difference between signal power and noise floor power for the second directional signal can also be determined whether it is the non-stationary contribution to the assumed useful signal, so for example a voice signal of a Conversation partner in a frontal direction to the user, or is a lateral non-stationary noise.

In an advantageous embodiment of the invention, a target value for a signal power of the output signal is specified, wherein the output adaptation coefficient is determined such that the actual signal power of the output signal has a minimum deviation from the target value. In particular, the determination of the output adaptation coefficient can be iterative. In the event that the first adaptation coefficient is determined on the basis of a minimum signal power of the signal resulting from the first superimposition, the first superimposition can be regarded as optimal with regard to the noise present at a particular time, stationary or non-stationary. A superposition of the first direction-dependent signal with the second direction-dependent signal on the basis of an adaptation coefficient deviating from the first adaptation coefficient is no longer optimal in this sense. In order to have a deterministically implementable criterion in this case for determining the output adaptation coefficient on the basis of the first and second adaptation coefficients, it is now proposed to specify a target value as the criterion for the signal power of the output signal resulting from the corresponding superimposition. In particular, the target value can be determined in a fixed ratio of the signal powers from the first and second superposition or a predetermined level distance to the above-mentioned minimum value of the signal power. The predetermined level distance can be, for example, 2 to 3 dB. In this way, when the first and the second adaptation coefficients have already been determined, the output adaptation coefficient can be adjusted based on that so that the signal power of the output signal corresponds to the target value or has a minimum deviation therefrom, if within the given values the target value is not reachable.

Conveniently, an instantaneous value of the output adaptation coefficient is formed by a linear combination of the first adaptation coefficient and the second adaptation coefficient. In particular, in this case a convex linear combination is to be understood, so that therefore the two linear factors to be used add up to 1 and both have a positive sign. A simple linear combination is computationally particularly easy to implement, which reduces the time required for signal processing to produce the output signal, and provides sufficiently good results as part of the SNR improvement requirement.

A first microphone signal is preferably generated in the hearing device from the sound signal by a first microphone and a second microphone signal is generated by a second microphone, wherein the first direction-dependent signal and / or the second direction-dependent signal are generated on the basis of the first microphone signal and the second microphone signal. A first microphone or a second microphone is to be understood here in general as an electroacoustic transducer which is set up to generate an electrical signal from a sound signal. In particular, the first direction-dependent signal and / or the second direction-dependent signal are each formed from the first microphone signal and the second microphone signal. In many hearing aid systems, even in binaural hearing aid systems, often only two microphones are present locally, so that corresponding direction-dependent signals in the hearing aid are formed locally from two microphone signals. In the case of a binaural hearing device system, further processing of the local direction-dependent signals for improvement can subsequently take place the directional effect. In the case where only two microphone signals are locally present in a hearing aid, the proposed method provides a particularly effective suppression of non-stationary noise while reducing stationary background noise.

Conveniently, in this case the first direction-dependent signal and / or the second direction-dependent signal are generated on the basis of a time-delayed superposition of the first microphone signal with the second microphone signal. Preferably, the acoustic transit time difference between the first microphone and the second microphone is used for the time delay in the overlay. This is a particularly easy-to-implement yet efficient method of generating a directional signal when the underlying microphone signals are from direction-independent microphones.

In this case, the first direction-dependent signal particularly preferably has a directional dependence in the form of a first cardioid, which is aligned in a first direction, and / or the second direction-dependent signal has a directional dependence in the form of a second cardioid, which is aligned in a second direction. A cardioid-shaped signal is characterized by the fact that the direction of minimum sensitivity is opposite to the direction of maximum sensitivity. This is not the case, for example, for signals whose directional characteristic forms a supercardioid or a hypercardioid. In addition, a sound signal from the direction of minimum sensitivity is ideally completely suppressed in a cardioid-shaped directional characteristic. The symmetry between the direction of maximum and minimum sensitivity thus makes it possible to keep calculations for the first and the second superimposition for noise suppression particularly simple, since in addition a strictly monotonous increase in sensitivity takes place from the direction of minimum sensitivity to the direction of maximum sensitivity , Particularly preferably, the first direction of the second direction is opposite in this case.

Against the background that in a directional signal with cardioid-shaped directional characteristic sound signals from the direction of minimum sensitivity in the ideal case In this way, the calculation of the first and second adaptation coefficients can be further simplified, since the first directional signal can be assumed to be a reference to the useful signal source, and in this case - if the second, cardioid-shaped, directional signal is opposite to first direction-dependent signal is aligned - a noise suppression by the second directional signal has no effect on the contribution of the desired signal. Thus, in order to determine the first or second adaptation coefficients for the most efficient possible noise suppression, a minimal signal power in the signal resulting from the first or second superimposition is required without this having an effect on the useful signal contribution.

The invention further mentions a hearing aid with a first microphone and a second microphone for generating a first direction-dependent signal and a second direction-dependent signal and with a control unit, which is configured to perform the method described above. The advantages stated for the method and its developments can be transferred analogously to the hearing aid.

FIG. 1

in einer Draufsicht die Abschwächung eines gerichteten Störsignals mittels einer Überlagerung zweier Richtsignale in einem Hörgerät, und

FIG. 2

in einem Blockdiagramm den Ablauf eines Verfahrens zur Abschwächung gerichteter Störsignale in einem Hörgerät.

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 plan view, the attenuation of a directional interference signal by means of a superposition of two directional signals in a hearing aid, and

FIG. 2

in a block diagram the sequence of a method for attenuation of directed interference signals in a hearing aid.

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

In Fig. 1 is shown schematically in a plan view a user 1 of a hearing aid 2. The user 1 is here in a conversation situation with a conversation partner 4, which is positioned with respect to the user 1 in its frontal direction 6. In a manner not shown, a first direction-dependent signal 8f (dashed line) and a second direction-dependent signal 8r (dotted line) are now formed in the hearing aid 2, the directional characteristic is given in each case by a cardioid. The Kardioid-shaped directional characteristic of the first directional signal 8f has the consequence that for sound signals from the frontal direction 6 is a maximum sensitivity and thus received sound signals from this direction maximum in the first directional signal 8f, while sound signals from the frontal direction 6 opposite reverse direction 10th ideally be completely suppressed in the first directional signal 8f. The second direction-dependent signal 8r has a direction dependence opposite to the first direction-dependent signal 8f, so that sound signals from the reverse direction 10 are received in the second direction-dependent signal 8r maximally, while sound signals from the frontal direction 6 are ideally completely suppressed.

Noise 12a, 12b, 12c, which do not come from the frontal direction 6, can now be attenuated in the hearing device 2 by superposing the first directional signal 8f with the second directional signal 8r of the form F + α · B, F and B being the first and second direction-dependent signals 8f, 8r, respectively, and α is an adaptation coefficient to be correspondingly selected. This exploits the fact that the useful signal source, in this case the interlocutor 4, is assumed to be in the frontal direction 6, and thus its contributions in the second directional signal 8r are completely suppressed, and therefore only by the first directional signal 8f in the signal resulting from the superposition F + α · B find input. The contribution of the second direction-dependent signal 8r is thus to be adapted in the resulting signal via the adaptation coefficient α such that the resulting signal has a minimal signal level, not least as a result of the constant input of the useful signal from the frontal direction 6 (see above) given a variation of .alpha posed is that the attenuation of the signal components, which do not come from the frontal direction 6, is maximum.

For the noise 12a, this can be achieved by a simple choice α = 0, so that in this case the resulting signal is equal to the first directional signal 8f and the noise 12a in it is completely suppressed. For the noise 12b, 12c, a non-trivial choice of α is required, wherein the amount of α for the noise 12b is to be selected smaller than in the case of the suppression of the noise 12c, as for the noise 12b already a much greater attenuation by the first directional signal 8f is reached, and thus by means of the second directional signal 8r only a smaller adjustment is required than is the case for the noise 12c coming from the front hemisphere of the user 2 and thus into the first directional signal 8f is much stronger.

If one of the interfering noises 12b, 12c now occurs in a non-stationary manner, ie with time intervals of significant signal contributions followed by time intervals without any signal activity, as is often the case with spoken speech, this leads to corresponding fluctuations in the adaptation coefficient α. In order to ensure effective suppression of the disturbing noises 12b, 12c, the adaptation coefficient α must be updated at sufficiently short time intervals. In the event that one of the two noise noises 12b, 12c, that is, for example, 12c, has a considerably non-stationary behavior, but the other noise 12b is substantially stationary, or alternatively or in addition thereto, there is a stationary background noise, the variation leads in the adaptation coefficient α, which is due to the fluctuations in the level of the noise 12c, the stationary noise 12b and / or the stationary background noise find more or less input into the signal resulting from the superimposition, depending on the activity of the noise 12c. In the event that there is only stationary background noise in addition to the non-stationary noise 12c, this may even result in non-trivial interference occurring only when the noise 12c is currently active, whereby in the resulting signal by the stationary noise components in the second directional signal 8b, the noise increases, and thereby degrades the SNR.

This problem is now to be prevented by a method 20 which is shown in the block diagram in FIG Fig. 2 is shown. In the hearing device 2, a first microphone signal 26a is generated from the sound signal 22 of the environment by means of a first microphone 24a, and a second microphone signal 26b is generated by means of a second microphone 24b. The second microphone signal 26b is delayed on the one hand by the time interval T, so that thereby a time-delayed second microphone signal 28b is formed, which is subtracted from the first microphone signal 26a, so that thereby the first directional signal 8f is formed. In the same way, the first microphone signal 26a is additionally delayed by the time interval T, thereby forming the first time-delayed microphone signal 28a, which is subtracted from the second microphone signal 26b, thereby forming the second direction-dependent signal 8r. The first direction-dependent signal 8f and the second direction-dependent signal 8r in this case each have the cardioid-shaped directional characteristics according to Fig. 1 on.

In a first adaptation block 30, a first adaptation coefficient a1 for a corresponding superposition of the first direction-dependent signal 8f with the second direction-dependent signal 8r is determined with a first reaction time t1 on the basis of the first direction-dependent signal 8f and the second direction-dependent signal 8r. In this case, the first reaction time t1 is preferably to be selected such that the first adaptation block determines the first adaptation coefficient a1 in such a way that a non-stationary noise in the sound signal 22 is particularly efficiently suppressed by a corresponding superposition F + α1 * B. This is done in particular by a signal resulting from such an overlay having a minimum signal power with respect to the reaction time t1.

In a second adaptation block 32, a second reaction time t2 is now determined based on the first direction-dependent signal 8f and the second direction-dependent one Signal 8r determines a second adaptation coefficient a2 for a corresponding superimposition of the first direction-dependent signal 8f with the second direction-dependent signal 8r. The second reaction time t2 is in the present case by at least a factor of 2 greater than the first reaction time t1. This has the consequence that the second adaptation block 32 responds more slowly to changes in the sound signal 22 than the first adaptation block 30, and is thus designed to suppress stationary noise by an overlay F + α2 · B as compared with the first adaptation block 30. For considerably non-stationary noise components in the sound signal 22, it may then be the case that a suddenly occurring noise component would already be suppressed by an adaptation according to the first adaptation block 30, while an adaptation according to the second adaptation block 32 in the corresponding second adaptation coefficient α2 as a result of the longer second reaction time t2 the noise component still not considered. However, largely stationary noise is always sufficiently taken into account by the second adaptation block 32.

In addition, a holding signal 36 is generated in a holding block 34 on the basis of the first direction-dependent signal 8f and the second direction-dependent signal 8r, which, in the event that non-stationary noise components are present in the sound signal 22, completely stops the updating of the second adaptation coefficient a2. That is, when non-stationary noise components in the first and second direction-dependent signals 8f, 8r are detected in the holding block 34, the value of the second adaptation coefficient α2 is no longer changed but remains at the value at the time of stopping. From now on, only the first adaptation coefficient α1 will continue to be updated as a function of the non-stationary noise components. If it is detected in the holding block 34 that there are no longer appreciable non-stationary noise components, a resume signal 38 is output to the second adaptation block 32, to which the second adaptation coefficient α2 is updated again with the second reaction time t2 in the second adaptation block 32. The decision in the holding block 34 whether 22 non-stationary noise components are present in the sound signal, so whether a stop signal 36 or a resume signal 38 is output, in particular by comparing the signal power with the noise floor power in the first directional signal 8f and in the second direction-dependent signal 8r done. For example, if there is only a small difference between the input power and the noise floor power in the second directional signal 8r, while there is a significant difference between the input power and the noise floor power for the first directional signal 8f, it can be assumed that in the forward cardioid area , which corresponds to the first directional signal 8f, there is a directed, non-stationary noise. In this case, by the output of a stop signal 36, the updating of the second adaptation coefficient α2 in the second adaptation block 32 is temporarily stopped until the corresponding non-stationary noise is no longer registered.

By means of a linear combination 40 of the first adaptation coefficient α1 with the second adaptation coefficient α2, an output adaptation coefficient α-out is now formed. An output signal 42 is then formed from the first directional signal 8f and the second directional signal 8r by a corresponding superposition of the form F + α-out · B. The linear combination 40 is of the form $$\mathrm{\alpha }-\mathrm{out}=\mathrm{\alpha }\mathrm{1}\cdot \mathrm{w}+\mathrm{\alpha }\mathrm{2}\cdot \left(\mathrm{1}-\mathrm{w}\right)$$

In this case, a target value for the signal power of the output signal 42 is specified for the determination of the parameter w. This may, for example, be 3 dB above the value of the output power which would have an output signal resulting from an overlap with the first adaptation coefficient α1, and would thus be minimal. The target value of the signal power of the output signal 42 thus represents a boundary condition, with respect to which the parameter w is relaxed, from the first optimum coefficient of adaptation α1 optimal for a minimum output power by the corresponding linear combination with a non-optimal second adaptation coefficient α2 to the output adaptation coefficient α-out, which is ultimately used for the superposition which generates the output signal 42.

By the proposed procedure can be achieved that are modulated at non-stationary noise components, especially in strongly directed, by the final applied adaptation less shares of a stationary noise floor in the output signal 42, if just a contribution of the non-stationary interference signal is present. This is done at the price of a no longer optimal suppression of the non-stationary interference signal, but this can be accepted, since the reduced co-modulation of the stationary noise nevertheless a better SNR and thus in particular improved speech intelligibility of the desired signal can be achieved.

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

user

2

hearing Aid

4

interlocutor

6

frontal direction

8f

first directional signal

8r

second directional signal

10

reverse direction

12a-c

interference

20

method

22

sound signal

24a / b

first / second microphone

26a / b

first / second microphone signal

28a / b

first / second time delayed microphone signal

30

first adaptation block

32

second adaption block

34

holding block

36

stop signal

38

Resume signal

40

linear combination

42

output

α1

first adaptation coefficient

α2

second adaptation coefficient

α-out

Output adaptation coefficient

T

time interval

t1

first reaction time

t2

second reaction time

Claims (11)

Method (20) for operating a hearing aid, wherein a first direction-dependent signal (8f) and a second direction-dependent signal (8r) are generated in the hearing device from a sound signal (22) of the surroundings, - Based on the first directional signal (8f) and the second directional signal (8r) a first adaptation coefficient (α1) for a first overlay (30) of the first directional signal (8f) with the second directional signal (8r) for noise suppression determined with a first reaction time (t1), - Based on the first directional signal (8f) and the second directional signal (8r), a second adaptation coefficient (α2) for a second overlay (32) of the first directional signal (8f) with the second direction-dependent signal (8r) for noise suppression determined with a second reaction time (t2), - Based on the first adaptation coefficient (α1) and the second adaptation coefficient (α2) an output adaptation coefficient (α-out) to form an output signal (42) by a superposition of the first directional signal (8f) and the second directional signal (8r) is determined. Method (20) according to claim 1,
wherein the second reaction time (t2) is greater than the first reaction time (t1). Method (20) according to claim 1 or claim 2,
wherein the second reaction time (t2) for determining the second adaptation coefficient (α2) is determined as a function of the first direction-dependent signal (8f) and the second direction-dependent signal (8r). Method (20) according to claim 3,
wherein the second reaction time (t2) for determining the second adaptation coefficient (α2) based on a difference between the signal power and a noise floor power for the first directional signal (8f) and / or based on a Difference between the signal power and a noise floor power for the second directional signal (8r) is determined. Method (20) according to one of the preceding claims,
wherein a target value for a signal power of the output signal (42) is given, and wherein the output adaptation coefficient (α-out) is determined such that the signal power of the output signal (42) has a minimum deviation from the target value. Method (20) according to one of the preceding claims,
wherein a current value of the output adaptation coefficient (α-out) is formed by a linear combination (40) of the first adaptation coefficient (α1) and the second adaptation coefficient (α2). Method (20) according to one of the preceding claims,
wherein in the hearing aid (2) from the sound signal (22) by a first microphone (24a), a first microphone signal (26a) is generated, and by a second microphone (24b), a second microphone signal (26b) is generated, and
wherein the first directional signal (8f) and / or the second directional signal (8r) are generated from the first microphone signal (26a) and the second microphone signal (26b). Method (20) according to claim 7,
wherein the first directional signal (8f) and / or the second directional signal (8r) are generated by means of a time-delayed superposition of the first microphone signal (26a) with the second microphone signal (26b). Method (20) according to claim 8,
wherein the first directional signal (8f) has directionality in the form of a first cardioid aligned in a first direction (6), and / or
wherein the second directional signal (8r) has a directional dependence in the form of a second cardioid aligned in a second direction (10). Method (20) according to claim 9,
wherein the first direction (6) is opposite to the second direction (10). Hearing aid (2) with a first microphone (24a) and a second microphone (24b) for generating a first direction-dependent signal (8f) and a second direction-dependent signal (8r) and with a control unit, which is adapted to the method (20) To carry out according to one of the preceding claims.

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