Hearing aid system including at least one hearing aid instrument worn on a user's head and method for operating such a hearing aid system

Abstract

A hearing aid system for assisting a user's ability to hear includes at least one hearing aid instrument worn on the user's head. A sound signal from the surroundings is recorded and converted into input audio signals by input transducers of the hearing aid system. The hearing aid system includes two adaptive beamformers with variable notch direction, applied indirectly or directly to the input audio signals to generate direction-dependently damped audio signals. The notch directions are set to mutually different values to minimize the energy content of the direction-dependently damped audio signal of each beamformer. The notch directions of the two beamformers are evaluated in comparative fashion. A user's head rotation is captured qualitatively and/or quantitatively if a correlated change in the notch directions is determined within the scope of the comparative evaluation. A method for operating the hearing aid system is also provided.

Claims

1. A method for operating a hearing aid system for assisting a user's ability to hear, the method comprising: providing at least one hearing aid instrument to be worn on a user's head or in or on an ear; using at least two input transducers of the hearing aid system to record and convert a sound signal from a user's surroundings into input audio signals; applying a first adaptive beamformer with a variable first notch direction indirectly or directly to the input audio signals for generating a first direction-dependently damped audio signal and setting the first notch direction to minimize an energy content of the first direction-dependently damped audio signal; applying a second adaptive beamformer with a variable second notch direction indirectly or directly to the input audio signals for generating a second direction-dependently damped audio signal and setting the second notch direction to a value differing from the first notch direction to minimize an energy content of the second direction-dependently damped audio signal; and evaluating the first notch direction and the second notch direction in comparative fashion and capturing a user's head rotation at least one of qualitatively or quantitatively upon determining a correlated change in the first notch direction and the second notch direction within a scope of the comparative evaluation.

2. The method according to claim 1, which further comprises at least one of generating a notification signal indicating the head rotation or capturing a time of the head rotation for the qualitative capture of the head rotation.

3. The method according to claim 1, which further comprises capturing a measured variable characteristic for at least one of a rate of rotation, a rotary angle interval, a duration of the head rotation or an orientation of the head in a surrounding space for the quantitative capture of the head rotation.

4. The method according to claim 1, which further comprises: applying at least one further adaptive beamformer with a variable further notch direction indirectly or directly to the input audio signals for generating a further direction-dependently damped audio signal and setting the further notch direction to a value differing from the notch directions of other beamformers to minimize an energy content of the further direction-dependently damped audio signal; and evaluating the first notch direction, the second notch direction and the at least one further notch direction in comparative fashion and capturing a user's head rotation at least one of qualitatively or quantitatively upon determining a correlated change in at least two of the notch directions within the scope of the comparative evaluation.

5. The method according to claim 1, which further comprises taking at least one of the notch directions into account with a different weighting in the comparative evaluation, depending on a magnitude of the energy minimization obtained by the variation in the at least one notch direction.

6. The method according to claim 1, which further comprises taking at least one of the notch directions into account with a different weighting in the comparative evaluation, depending on a time stability of the at least one notch direction.

7. The method according to claim 1, which further comprises using a number of signal processing processes to indirectly or directly modify the input audio signals, depending on a number of adjustable signal processing parameters, in a signal processing unit of the at least one hearing aid instrument in order to be output to the user by using an output transducer of the hearing aid instrument and setting at least one signal processing parameter depending on at least one of the qualitative or quantitative capture of the head rotation.

8. The method according to claim 1, which further comprises using at least one adaptive signal processing process to indirectly or directly modify the input audio signals, depending on an adjustable adaptation speed, in a signal processing unit of the at least one hearing aid instrument in order to be output to the user by using an output transducer of the hearing aid instrument and setting the adaptation speed depending on at least one of the qualitative or quantitative capture of the head rotation.

9. A hearing aid system for assisting a user's ability to hear, the hearing aid system comprising: at least one hearing aid instrument to be worn on a user's head or in or on an ear; at least two input transducers of the hearing aid system for recording a sound signal from the user's surroundings and for converting the sound signal into input audio signals; a first adaptive beamformer of the hearing aid system with a variable first notch direction indirectly or directly receiving the input audio signals, said first adaptive beamformer configured to generate a first direction-dependently damped audio signal and to set the first notch direction to minimize an energy content of the first direction-dependently damped audio signal; a second adaptive beamformer of the hearing aid system with a variable second notch direction indirectly or directly receiving the input audio signals, said second adaptive beamformer configured to generate a second direction-dependently damped audio signal and to set the second notch direction to minimize an energy content of the second direction-dependently damped audio signal; and an evaluation unit of the hearing aid system configured to evaluate the first notch direction and the second notch direction in comparative fashion and to at least one of qualitatively or quantitatively capture a user's head rotation upon said evaluation unit determining a correlated change in the first notch direction and the second notch direction within a scope of the comparative evaluation.

10. The hearing aid system according to claim 9, wherein said evaluation unit is configured to at least one of generate a notification signal indicating the head rotation or capture a time of the head rotation for the qualitative capture of the head rotation.

11. The hearing aid system according to claim 9, wherein said evaluation unit is configured to capture at least one of a variable characteristic for a rate of rotation, a rotary angle interval, a duration of the head rotation or an orientation of the head in a surrounding space for the quantitative capture of the head rotation.

12. The hearing aid system according to claim 9, which further comprises: at least one further adaptive beamformer of the hearing aid system with a variable further notch direction indirectly or directly receiving the input audio signals, said further adaptive beamformer configured to generate a further direction-dependently damped audio signal and to set the further notch direction to a value differing from the notch directions of other beamformers to minimize an energy content of the further direction-dependently damped audio signal; and said evaluation unit configured to evaluate the first notch direction, the second notch direction and the at least one further notch direction in comparative fashion and to capture a user's head rotation at least one of qualitatively or quantitatively upon determining a correlated change in at least two of the notch directions within a scope of the comparative evaluation.

13. The hearing aid system according to claim 9, wherein said evaluation unit is configured to take into account at least one of the notch directions with a different weighting in the comparative evaluation, depending on a magnitude of the energy minimization obtained by the variation in the at least one notch direction.

14. The hearing aid system according to claim 9, wherein said evaluation unit is configured to take into account at least one of the notch directions with a different weighting in the comparative evaluation, depending on a time stability of the at least one notch direction.

15. The hearing aid system according to claim 9, which further comprises a signal processing unit of said at least one hearing aid instrument configured to modify the input audio signals or audio signals derived from the input audio signals, by using a number of signal processing processes, depending on a number of adjustable signal processing parameters, in order to be output to the user by using an output transducer of the hearing aid instrument and a device of the hearing aid system for setting at least one signal processing parameter depending on at least one of the qualitative or quantitative capture of the head rotation.

16. The hearing aid system according to claim 9, which further comprises a signal processing unit of the at least one hearing aid instrument configured to modify the input audio signals or audio signals derived from the input audio signals, by using at least one adaptive signal processing process, depending on an adjustable adaptation speed, in order to be output to the user by using an output transducer of the hearing aid instrument and a device of the hearing aid system for setting the adaptation speed depending on at least one of the qualitative or quantitative capture of the head rotation.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 is a diagrammatic, plan view of a hearing aid system formed of a single hearing aid instrument and being in the form of a hearing aid that is wearable behind an ear of a user;

(2) FIG. 2 is a schematic and block diagram of the structure of signal processing of the hearing aid instrument of FIG. 1; and

(3) FIG. 3 is an illustration similar to FIG. 1, showing an alternative embodiment of the hearing aid system in which the latter includes a hearing aid instrument in the form of a behind-the-ear hearing aid and a control program implemented on a smartphone (“hearing app”).

DETAILED DESCRIPTION OF THE INVENTION

(4) Referring now in detail to the figures of the drawings, in which parts and variables corresponding to one another are always provided with the same reference signs, and first, particularly, to FIG. 1 thereof, there is seen a hearing aid system 2 which is formed in this case of a single hearing aid 4, i.e., a hearing aid instrument configured to assist the ability of a hearing-impaired user to hear. In the example illustrated herein, the hearing aid 4 is a BTE hearing aid, which is able to be worn behind an ear of a user.

(5) Optionally, in a further embodiment of the invention, the hearing aid system 2 includes a second hearing aid, not expressly illustrated, which serves to supply the second ear of the user and which, in particular, corresponds in terms of its setup to the hearing aid 4 illustrated in FIG. 1.

(6) Within a housing 5, the hearing aid 4 includes two microphones 6 as input transducers and a receiver 8 as an output transducer. The hearing aid 4 furthermore includes a battery 10 and signal processing in the form of a signal processor 12. Preferably, the signal processor 12 includes both a programmable subunit (e.g., a microprocessor) and a non-programmable subunit (e.g., an ASIC).

(7) The signal processor 12 is fed with a supply voltage U from the battery 10.

(8) During normal operation of the hearing aid 4, the microphones 6 each record airborne sound from the surroundings of the hearing aid 4. The microphones 6 each convert the sound into an (input) audio signal I1 and I2, respectively, which contains information about the recorded sound. Within the hearing aid 4, the input audio signals I1, I2 are fed to the signal processor 12, which modifies these input audio signals I1, I2 to assist the ability of the user to hear.

(9) The signal processor 12 outputs an output audio signal O, which contains information about the processed and hence modified sound, to the receiver 8.

(10) The receiver 8 converts the output audio signal O into a modified airborne sound. This modified airborne sound is transferred into the auditory canal of the user through a sound channel 14, which connects the receiver 8 to a tip 16 of the housing 5, and through a flexible sound tube (not explicitly shown), which connects the tip 16 with an earpiece inserted into the auditory canal of the user.

(11) The structure of the signal processing is illustrated in more detail in FIG. 2. From this, it is evident that the signal processing of the hearing aid system 2 is organized in two functional constituent parts, specifically a signal processing unit 18 and a signal analysis unit 20. The signal processing unit 18 serves to generate the output audio signal O from the input audio signals I1, I2 of the microphones 6 or, therefrom, from internal audio signals I1′, I2′ derived from pre-processing. In the case mentioned first, the input audio signals I1, I2 of the microphones 6 are directly fed to the signal processing unit 18. In the latter case, illustrated in FIG. 2 in exemplary fashion, the input audio signals I1, I2 of the microphones 6 are initially fed to a pre-processing unit 22, which then derives the internal audio signals I1′, I2′ therefrom and supplies these to the signal processing unit 18.

(12) In the pre-processing unit 22, the input audio signals I1, I2 are preferably superposed on one another with a time offset to form the internal audio signals I1′, I2′, in such a way that the two internal audio signals I1′, I2′ correspond to a cardioid signal or an anti-cardioid signal.

(13) The signal processing unit 18 includes a number of signal processing processes 24, which successively process the input audio signals I or—in the example as per FIG. 2—the internal audio signals I1′, I2′ and modify these in the process in order to generate the output audio signal O and hence compensate the loss of hearing of the user.

(14) By way of example, the signal processing processes 24 include:

(15) a process for suppressing noise and/or feedback,

(16) a process for dynamic compression and

(17) a process for frequency-dependent amplification on the basis of audiogram data,

(18) etc.

(19) In this case, at least one signal processing parameter P is assigned in each case to at least one of these signal processing processes 24 (as a rule, to all signal processing processes 24 or at least to most signal processing processes 24). The signal processing process 24 or each signal processing process 24 is a one-dimensional variable (binary variable, natural number, floating-point number, etc.) or a multi-dimensional variable (array, function, etc.), the value of which parameterizes (i.e., influences) the functionality of the respectively assigned signal application process 24. In this case, signal processing parameters P can activate or deactivate the respectively assigned signal processing process 24, can continuously or incrementally amplify or weaken the effect of the respectively assigned signal processing process 24, can define time constants for the respective signal processing process 24, etc.

(20) By way of example, the signal processing parameters P include:

(21) gain factors for a process for frequency-dependent amplification,

(22) a characteristic for a process for dynamic compression,

(23) a control variable for continuously setting the strength of a process for noise and/or feedback suppression,

(24) etc.

(25) Furthermore, at least one of the signal processing processes 24 preferably is an adaptive process, the adaptation speed of which can be variably set by using one of the signal processing parameters P. By way of example, the signal processing processes 24 include an adaptive “beamformer” with variable adaptation speed, which is set up to direction-dependently damp the input audio signals I1, I2 (or the internal audio signals I1′, I2′ derived therefrom) in order to generate the output audio signal O.

(26) By way of example, the signal processing processes 24 are implemented partly in the form of (non-programmable) hardware circuits and, in another part, in the form of software modules (in particular firmware) in the signal processor 12.

(27) The signal analysis unit 20 includes—preferably in addition to other functions, not illustrated explicitly in this case, for analyzing sound, such as, e.g., a classifier for analyzing hearing situations—a head rotation detection unit 26, which is preferably implemented in the signal processor 12 in the form of software. The head rotation detection unit 26 includes a plurality of beamformers 28 with the same structure, i.e., processes for direction-dependent damping, which are each fed with the input signals I1, I2 or—as illustrated in the example as per FIG. 2—the internal audio signals I1′, I2′ derived therefrom and which each output a direction-dependently damped audio signal R. Each beamformer 28 generates the associated direction-dependently damped signal R by virtue of superposing the two fed audio signals I1′, I2′ (i.e., a cardioid signal and an anti-cardioid signal in the example as per FIG. 2), which are weighted by using a weighting factor a:
R=I1′−a.Math.I2′ where a=[−1;1]  Eq. 1

(28) In this case, the weighting factor a determines the value of a notch direction N which—as is seen relative to the head of the user—indicates the direction in which the respective beamformer 28 maximally damps the fed audio signals I1′, I2′. In this case, the weighting factor a and the notch direction are uniquely correlated with one another by way of a nonlinear mathematical function (N=N(a)) and can consequently be converted into one another.

(29) The beamformers 28 (three beamformers 28a, 28b and 28c in the example according to per FIG. 2) each have an adaptive embodiment. In this case, each beamformer 28 is set up to automatically set the weighting factor a (and hence the notch direction N) in such a way that the energy content of the direction-dependently damped audio signal R output thereby is minimized. Consequently, the direction-dependently damped audio signal R is a function of the weighting factor a (R=R(a)) or, equivalently, a function of the notch direction N (R=R(N)).

(30) To this end, the direction-dependently damped signal R output by each beamformer 28 is returned thereto. As a measure for the energy minimization, and hence for setting the weighting factor a (and consequently the notch direction N), each beamformer 28 for example determines the ratio of the squared levels of the direction-dependently damped audio signal R and of the internal audio signals I1′, I2′

(31) $\begin{array}{cc}{E}_R=\frac{{.Math.R\left(a\right).Math.}^2}{0.5.Math.\left({.Math.I{1}^{\prime }.Math.}^2+{.Math.I{2}^{\prime }.Math.}^2\right)}& \mathrm{Eq}.2\end{array}$

(32) and minimizes, for example using Newton's method, this variable while varying the weighting factor a. As an alternative to Newton's method, use is made, for example, of the conjugate gradient method (CG method).

(33) In the example as per FIG. 2, the beamformers 28 only serve to analyze the input audio signals I1, I2 or the internal audio signals I1′, I2′. Therefore, the direction-dependently damped audio signals R of these beamformers 28 are not output by the receiver 8 or processed further for an output.

(34) From the weighting factor a, each beamformer 28 calculates the associated notch direction N and outputs this notch direction N to a downstream evaluation unit 30. Moreover, each beamformer 28 also outputs the notch direction N set thereby to a possibly subordinate beamformer 28. Thus, the beamformer 28a as per FIG. 2 outputs the notch direction N set thereby to the beamformers 28b and 28c while the beamformer 28b outputs the notch direction N set thereby to the beamformer 28c. In this case, each beamformer 28 is set up to leave out the notch directions N of the superordinate beamformers 28 fed thereto (in each case observing a distance interval of, e.g., ±5°) when setting its own notch direction N. Consequently, the beamformers 28a, 28b, 28c form a cascade of coupled beamformers 28, in which each beamformer 28 necessarily sets a different notch direction N and consequently aligns with a different source of noise.

(35) The evaluation unit 30 compares the time profile of the fed notch directions N to one another. As soon as the evaluation unit 30 determines a correlated change of at least two of the fed notch directions N, the evaluation unit 30 identifies this as an indication of the user having moved their head. In this case, the evaluation unit 30 generates a notification signal D indicating the head rotation and feeds this notification signal D to the signal processing unit 18.

(36) Within the signal processing unit 18, the notification signal D is supplied to a parameterization unit 32, which provides the signal processing parameters P for the signal processing processes 24. In this case, the parameterization unit 32 provides at least one of the signal processing parameters P with a value that varies depending on the notification signal D. Consequently, the parameterization unit 32 controls at least one of the signal processing processes 24 differently when the head rotation detection unit 26 identifies a head rotation than in the periods of time during which the head rotation detection unit 26 does not detect a head rotation. Provided the signal processing processes 24 include an adaptive process, in particular an adaptive beamformer, with a variable adaptation speed, this adaptation speed is preferably varied by the parameterization unit 32 on the basis of the indication signal D. In particular, the parameterization unit 32 increases the adaptation speed during and just after the head rotation in such a way that the adaptive process can quickly adapt to the change in the hearing situation caused by the head rotation. During periods of time in which the head rotation detection unit 26 does not detect a head rotation, the adaptation speed is by contrast reduced to a comparatively low value by the parameterization unit 32. Consequently, in the absence of a head rotation, the adaptive signal processing process is set with comparatively high inertia in order to ensure stable signal processing. In addition, or as an alternative to the increase in the adaptation speed, the parameterization unit 32 temporarily reduces the strength of the directional effect (in particular the notch depth) during and just after the identified head rotation, which avoids some artifacts of the signal processing and facilitates a better orientation of the hearing aid wearer.

(37) In order to determine correlated changes of at least two of the fed notch directions N, the evaluation unit 30 forms, in each case in pairwise fashion, the cross-correlation function between the fed notch directions N. In this case, the evaluation unit 30 identifies the presence of a head rotation if the value of at least one of the cross-correlation functions formed exceeds a given threshold.

(38) In an alternative embodiment, the evaluation unit 30 in each case captures the start and end times of changes and the respective change amplitude (i.e., the value by which the respective notch direction N has changed) for each of the fed notch directions N. In this case, it identifies the presence of a head rotation if at least two of the fed notch directions N each have a change with (within specified tolerance ranges) the same start and end times and the same change amplitude.

(39) In yet a further alternative, the evaluation unit 30 captures the sign and/or the magnitude of the temporal change (in particular the sign of the first time derivative) for each of the fed notch directions N. In this case, it identifies the presence of a head rotation if a sufficiently large number of the determined signs are equal (thus, for example, if all notch directions N, optionally apart from the notch direction N of a beamformer 28 adapted to the user's own voice, change in the same direction) or if a plurality of notch directions N experience a change of equal magnitude.

(40) However, in both cases, the evaluation unit 30 generates the notification signal D upon identification of a head rotation only once the change in the correlated notch directions N exceeds a specified threshold, for example 10° (i.e., if the correlated notch directions N have changed by more than the specified threshold).

(41) In a simple embodiment of the hearing aid system 2, the notification signal D is a variable which only provides qualitative notification of the identified head rotation without characterizing this head rotation in any more detail. By way of example, the evaluation unit 30 places a flag, as soon as and for as long as it identifies a head rotation, as a notification signal D.

(42) However, in addition or as an alternative to the purely qualitative indication for the head rotation, the notification signal D preferably contains at least one specification which qualitatively characterizes the identified head rotation, in particular a specification relating to the rotary angle through which the head is rotated and/or relating to the rate of rotation (i.e., the angular speed) of the head rotation.

(43) In order to ensure that each beamformer 28 can adapt its notch direction R in real time in the case of a head rotation but, at the same time, to avoid the notch direction N jumping back and forth between different sources of noise, each beamformer 28 is preferably set up to vary its adaptation speed depending on the magnitude of the energy minimization, in particular depending on the value of the variable ER as per Eq. 2. For as long as a certain beamformer 28 is aligned with an active source of noise and consequently the energy minimization for the set notch direction N is sufficiently large (for example, if and for as long as the variable ER is below a given limit), this beamformer 28 sets its adaptation speed to a comparatively high value in such a way that, for example, a rate of change of the notch direction N of up to 180° per second is facilitated. Otherwise, i.e., if it is temporarily not possible to obtain a significant energy minimization by varying the weighting factor a (and hence the notch direction N), the beamformer 28, or each affected beamformer 28, reduces its adaptation speed in such a way that, for example, the admissible rate of change of the notch direction is restricted to ±2° per second. What this reduction in the adaptation speed achieves is that the beamformers 28 maintain their alignment with a certain source of noise, even if this source of noise is briefly inactive.

(44) Beamformers 28 which, as described above, do not attain any significant energy minimization (for example, because they are not yet or no longer aligned with a dominant source of noise or because their associated source of nose has briefly become inactive) are referred to as “searching” below in order to simplify the language.

(45) In order to prevent such a searching beamformer 28 from disturbing the comparative evaluation of the notch directions N undertaken by the evaluation unit 30, the beamformers 28 are preferably set up to output the set notch direction N to the evaluation unit 30 and the downstream beamformers 28 only if and only after they have aligned with an active, dominant source of noise and are consequently no longer searching.

(46) In order to ensure that the head rotation detection unit 26 adapts to changing hearing situations and that, in particular, the evaluation unit 30 only takes account of the notch directions N of those beamformers 28 that have aligned with a dominant and long-term active source of noise, the beamformers 28 are dynamically (by using software, for example as objects of the same class) generated (activated) during the operation of the hearing aid system 2 and ended (deactivated) when necessary in a preferred embodiment of the hearing aid system 2.

(47) By way of example, the head rotation detection unit 26 generates a new beamformer 28 at regular time intervals (e.g., every 60 seconds) and orders the latter right at the bottom of the cascade of coupled beamformers 28.

(48) Should one of the beamformers 28 be permanently searching during a given time interval (of 40 seconds, for example) and consequently be unable to attain any significant energy minimization (in particular should the variable ER permanently be below the limit for the specified time interval), this beamformer 28 deactivates itself autonomously and is consequently removed from the cascade of coupled beamformers 28.

(49) What the above-described automatic activation and deactivation of the beamformers 28 ensures is that the number of the beamformers 28 (active within the scope of the head rotation detection unit 26) is regularly adapted to the number of dominant sources of noise in the surroundings of the user. However, to avoid a numerical overload of the signal processor 12, the number of simultaneously active beamformers 28 is preferably restricted to a specified maximum number, e.g., five beamformers 28.

(50) In a variant of the hearing aid system 2 not explicitly illustrated, the evaluation unit 30 acts back on the beamformers 28 by virtue of, in the case of an identification of a head rotation, triggering an adaptation of the notch direction N of the or each searching beamformer 28 through the angle of the identified head rotation. Consequently, the beamformers 28 remain aligned with their associated source of noise in the case of a head rotation, even if their source of noise was briefly inactive during the head rotation. Consequently, the beamformer 28 is immediately utilizable again as soon as the source of noise becomes active again, even during and after the head rotation.

(51) FIG. 3 shows a further embodiment of the hearing aid system 2, in which the latter includes control software in addition to the hearing aid 4 (or two hearing aids of this type for supplying the two ears of the user). This control software is referred to as a hearing app (or application) 40 below. The hearing app 40 is installed on a smartphone 42 in the example illustrated in FIG. 3. In this case, the smartphone 42 itself is not part of the hearing aid system 2. Rather, the smartphone 42 is only used as a resource for memory and computing power by the hearing app 40.

(52) The hearing aid 4 and the hearing app 40 exchange data through a wireless data transmission link 44 during the operation of the hearing aid system 2. By way of example, the data transmission link 44 is based on the Bluetooth standard. In this case, the hearing app 40 accesses a Bluetooth transceiver of the smartphone 42 in order to receive data from the hearing aid 4 and in order to transmit data to the latter. In turn, the hearing aid 4 includes a Bluetooth transceiver (not explicitly illustrated) in order to transmit data to the hearing app 40 and to receive data from this app.

(53) In the embodiment as per FIG. 3, some of the software components required to carry out the method as per FIG. 2 are not implemented in the signal processor 12 but instead in the hearing app 40. By way of example, the evaluation unit 30 is implemented in the hearing app 40 in the embodiment as per FIG. 3.

(54) The invention becomes particularly clear on the basis of the above-described exemplary embodiments although it is equally not restricted to these exemplary embodiments. Rather, further embodiments of the invention can be derived by a person skilled in the art from the claims and the above description.

(55) The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: 2 Hearing aid system 4 Hearing aid 5 Housing 6 Microphone 8 Receiver 10 Battery 12 Signal processor 14 Sound channel 16 Tip 18 Signal processing unit 20 Signal analysis unit 22 Pre-processing unit 24 Signal processing process 26 Head rotation detection unit 28 Beamformer 28a-28c Beamformer 30 Evaluation unit 32 Parameterization unit 40 Hearing app 42 Smartphone 44 Data transmission link a Weighting factor D Notification signal I1, I2 Input audio signal I1′, I2′ (Internal) audio signal N Notch direction O Output audio signal P Signal processing parameter R (Direction-dependently damped) audio signal U Supply voltage