METHOD FOR REDUCING THE OCCURRENCE OF ACOUSTIC FEEDBACK IN A HEARING DEVICE AND HEARING DEVICE

Abstract

In a method that reduces the occurrence of acoustic feedback in a hearing device, a first wearing situation is created that determines a positioning of the hearing device relative to the wearer. For the first wearing situation, a first usage situation is created being a body movement of the wearer of the hearing device and/or a relative position of an external object relative to the body of the wearer. A first number of frequency-resolved curves of a feedback tendency of the hearing device are determined for the first use situation. A first criticality measure is ascertained based on the frequency-resolved curve for the first use situation that contains information on a frequency range that is critical with respect to an occurrence of acoustic feedback and a corresponding relative probability of acoustic feedback, and a target is established for adapting a hearing device parameter based on the first criticality measure.

Claims

1. A method for reducing an occurrence of acoustic feedback in a hearing device, which comprises the steps of: creating a first wearing situation that determines a positioning of the hearing device relative to a wearer; creating, for the first wearing situation, a first usage situation that is characterized by at least one body movement of the wearer of the hearing device and/or at least one relative position of an external object relative to the body of the wearer; determining a first number of frequency-resolved curves of a feedback tendency of the hearing device for the first use situation; ascertaining a first criticality measure based on at least one of the frequency-resolved curves for the first use situation that contains information on a frequency range that is critical with respect to the occurrence of the acoustic feedback and a corresponding relative probability of acoustic feedback; and establishing a target for adapting at east one hearing device parameter based on the first criticality measure.

2. The method according to claim 1, which further comprises: determining a plurality of the frequency-resolved curves of the feedback tendency for the first use situation; and establishing at a given frequency, the first criticality measure for the first use situation at that frequency based on a dispersion measure for values of the feedback tendency that respectively result from the plurality of frequency-resolved curves.

3. The method according to claim 1, which further comprises: measuring an attenuation of an acoustic feedback path; and determining the feedback tendency at a given frequency respectively by means of signal amplification in the hearing device and by means of the attenuation of the acoustic feedback path.

4. The method according to claim 1, which further comprises establishing the first use situation by at least one of: the wearer putting on headgear; the wearer moving a jaw; the wearer using a mobile telephone near the hearing device; the wearer engaging in a sporting activity; or the wearer being positioned in an immediate vicinity of a spatial boundary.

5. The method according to claim 1, which further comprises selecting the at least one hearing device parameter from the group consisting of: a total gain at one frequency; a compression characteristic curve at a frequency; and a readjustment speed.

6. The method according to claim 1, which further comprises: establishing a second use situation for the first wearing situation; ascertaining a second criticality measure for the second use situation; and establishing the target for adapting the at least one hearing device parameter and/or an additional hearing device parameter based on the second criticality measure.

7. The method according to claim 1, which further comprises: adapting the at least one hearing device parameter in accordance with the target that was established based on the first criticality measure; operating the hearing device with an adapted hearing device parameter in a test mode; establishing the first use situation in the test mode; and ascertaining a third criticality measure for checking an adaptation for the first use situation in the test mode.

8. The method according to claim 1, which further comprises: establishing a second wearing situation; establishing the first use situation for the second wearing situation; ascertaining a fourth criticality measure for the first use situation in the second wearing situation; and establishing the target with regard to a suitability of the second wearing situation for operating the hearing device based on the fourth criticality measure.

9. The method according to claim 8, wherein based on the fourth criticality measure, the target is established with respect to a suitability of the second wearing situation for operating the hearing device with the at least one hearing device parameter that has been adapted based on the first criticality measure.

10. The method according to claim 8, which further comprises establishing the second wearing situation by: a position correction of an acoustic coupling piece of the hearing device; and/or use of the acoustic coupling piece with modified dimensions; and/or use of the acoustic coupling piece with a modified ventilation opening.

11. The method according to claim 1, which further comprises detecting at least the first wearing situation and the first use situation by means of a video recording system.

12. The method according to claim 11, which further comprises: transmitting image data that the video recording system has generated to a video playback system spatially separated from the wearer, the video playback system reproducing the image data; and/or generating an automatic command for determining a number of the frequency-resolved curves (34a-c, 44a-c, 54a-c, 60a-m) of the feedback tendency of the hearing device in the first use situation from the image data that the video recording system has generated.

13. A hearing device, comprising: components for performing a method for reducing an occurrence of acoustic feedback in the hearing device, said components programmed to: create a first wearing situation that determines a positioning of the hearing device relative to a wearer; create, for the first wearing situation, a first usage situation that is characterized by at least one body movement of the wearer of the hearing device and/or at least one relative position of an external object relative to the body of the wearer; determine a first number of frequency-resolved curves of a feedback tendency of the hearing device for the first use situation; ascertain a first criticality measure based on at least one of the frequency-resolved curves for the first use situation that contains information on a frequency range that is critical with respect to the occurrence of the acoustic feedback and a corresponding relative probability of acoustic feedback; and establish a target for adapting at least one hearing device parameter based on the first criticality measure.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0036] FIG. 1 is a block diagram of a hearing device in which acoustic feedback occurs;

[0037] FIG. 2 is a block diagram of a method for reducing a feedback tendency in a hearing device as a function of a wearing situation and according to the invention;

[0038] FIG. 3 is a graph diagram of a feedback tendency plotted against a frequency; and

[0039] FIG. 4 is a graph diagram of a plurality of feedback tendencies for different use situations and a resulting criticality measure.

DETAILED DESCRIPTION OF THE INVENTION

[0040] Components and magnitudes that correspond to each other are respectively assigned the same reference signs in all drawings.

[0041] Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown a schematic block diagram of a hearing device 1. An input transducer 2 of the hearing device 1, here configured as a microphone, converts a sound signal 4 from the environment into an input signal 6. The input signal 6 is fed to signal processing 8 in the hearing device 1 and processed there according to the audiological requirements of the wearer of the hearing device 1, and is amplified in particular in a frequency-band-specific manner. An output transducer 12 of the hearing device 1 converts the output signal 10 that results from the signal processing 8 into an output sound signal 14 that is fed to the hearing system (not otherwise shown) of the wearer of the hearing device 1. The output transducer 14 in this case is provided as a loudspeaker that is arranged in an acoustic coupling piece 15 of the hearing device 1. The acoustic coupling piece in this case is provided as an earpiece. Along an acoustic feedback path 16, a part of the output sound signal 14 may now return to the input transducer 2, and thus find its way into the input signal 6, forming a closed feedback loop in which the signal processing 8 continuously amplifies signal components.

[0042] To suppress the acoustic feedback that occurs in this case, the gain may be reduced in the signal processing 8. However, such a reduction also entails a loss of gain for other signal components that acoustic feedback does not affect, so that the signal processing 8 no longer functions optimally according to the audiological requirements of the wearer of the hearing device 1. To ensure suppression of acoustic feedback even when these requirements are taken into account, the output signal 10 is often branched off and fed to an adaptive filter 18. Doing so generates a compensation signal 20 that is fed to the input signal 6 and subtracted from it. The signal that results from this subtraction is fed into both the signal processing 8 and the adaptive filter as an error signal 22. In the adaptive filter 18 in particular, the acoustic feedback path 16 and its frequency response are estimated.

[0043] However, in some situations, subtracting the compensation signal 20 from the input signal 6 may lead to undesired effects, for example artifacts in the output signal 10. The speed at which the feedback path estimate is updated determines a variable time parameter of the adaptive filter 18. The shorter this time parameter is set, the faster the feedback suppression adapts to a change in the acoustic feedback path. However, user may perceive the rapid readjustment as a disturbing artifact equally more frequently. In this respect, a trade-off must be chosen for a pleasant sound experience that is as free as possible from feedback.

[0044] Moreover, the occurrence of acoustic feedback sometimes also has predominantly mechanical causes, for example a non-optimal seating of the acoustic coupling piece 15 of the hearing device 1 in the wearer's ear such that a particularly high proportion of the output sound signal 14 escapes and may reach the input transducer 2 again. Other causes that are substantially mechanical may depend on a specific use situation such as chewing or speaking, or the influence of a mobile telephone or other similar object on the acoustic feedback path 16 near the hearing device 1. In this case, feedback suppression by the adaptive filter 18, with the associated risk of artifacts in the output signal 10, is not always effective. On the other hand, it may be useful or desirable to make the acoustic feedback that occurs as a function of the specific use situation more difficult from the outset, without significantly restricting the playback dynamics of the hearing device 1.

[0045] This is shown in FIG. 2 in a block diagram which has a corresponding method as its subject matter. First, a first wearing situation 30 is created in which the wearer regularly fits the hearing device 1 according to FIG. 1. The first wearing situation 30 is characterized in particular by the global positioning of the hearing device 1 relative to the wearer, and also by the use of individual, reversibly exchangeable components such as an acoustic coupling piece 15 and their positioning relative to the wearer. In the first wearing situation 30, a first use situation 32 is now produced, which is characterized by at least one body movement of the wearer and/or an external object. This may be done, for example, by the wearer wearing headgear such as a hat or cap, making a jaw movement while speaking or chewing, or using a mobile telephone near the hearing device. During the first use situation, a plurality of frequency-resolved curves 34a-c of a feedback tendency of the hearing device are determined. This is done, for example, by repeating the measurement process for the feedback tendency by repeating the movement that corresponds to the first use situations, and generating a plurality of screenshots of the feedback tendency for the frequency over time. From the frequency-resolved curves 34a-c of the feedback tendency, a first criticality measure 36 is generated as described below, and based on this measure, a target 38 is established for adapting at least one hearing device parameter.

[0046] In an analogous manner not otherwise shown, a second use situation may also be created in the first wearing situation 30, and in this second situation, frequency-resolved curves of a feedback tendency of the hearing device 1 are likewise determined according to FIG. 1, and from these, a second criticality measure is ascertained. Based on the second criticality measure thus ascertained, a target may likewise be established for adapting one or more hearing device parameters, and the target may involve the hearing device parameter 40, for which a target 38 for adaptation has already been established based on the first criticality measure 36. The target established based on the second criticality measure may also affect other hearing device parameters for which no target yet exists.

[0047] The hearing device parameter 40 is now adjusted according to the target 38 and optionally according to another target that has been created in a second use situation. The hearing device parameter 40 may, for example, be a total gain at a specific frequency and/or a compression characteristic curve at a specific frequency, but it may also be a parameter of the adaptive filter 18 according to FIG. 1, for example a readjustment speed or a step size. Now a test mode 42 is started in which the hearing device 1 is tested in the first use situation 32. Here again, frequency-resolved curves 44a-c are ascertained for the feedback tendency of the hearing device. The frequency-resolved curves 44a-c are thus generated, while the motion corresponding to the first use situation is repeated in the test mode 42. A third criticality measure 46 is generated from the frequency-resolved curves 44a-c analogously to the first criticality measure 36. Based on the third criticality measure 46, it may now be determined whether adapting the hearing device parameter 40 according to the target 38 has significantly reduced the probability of acoustic feedback in the first use situation 32.

[0048] If it has not, a second wearing situation 50 is proposed. This wearing situation may be, for example, a correction of the position of the acoustic coupling piece 15 of the hearing device 1, or the use of an acoustic coupling piece with modified dimensions and/or modified ventilation openings. After the corresponding action has been proposed that characterizes the second wearing situation 50, which may occur in particular automatically, the wearer of hearing device 1 or a trusted person creates the second wearing situation. Next, the first use situation is created again for the second wearing situation 50 by the corresponding movement. Once again, frequency-resolved curves 54a-c for the feedback tendency are ascertained, and a fourth criticality measure 56 is determined on that basis. Using the fourth criticality measure 56, it may now be checked whether, according to the first criticality measure 36, the target established for the adapting of the hearing device parameter 40 in the second wearing situation 50 is suitable to keep the probability of acoustic feedback sufficiently low. If so, the second wearing situation 50 may be identified as the wearing situation to be used henceforth, for example by continuing to use a replaced acoustic coupling piece if appropriate, or by continuously ensuring that the acoustic coupling piece penetrates properly into the ear canal, if necessary, when applying the acoustic coupling piece. If the fourth criticality measure 56 does not suggest any significant improvement in the feedback tendency, then either a third wearing situation (not otherwise shown) may be created in a similar way to the second wearing situation 50, or the visit to a hearing device acoustician may be recommended as a last resort measure.

[0049] FIG. 3 shows a diagram with a feedback tendency 60 plotted in dB against the frequency f. The feedback tendency 60, which represents a probability of acoustic feedback occurring, is calculated in this case by adding the attenuation 62 of the acoustic feedback path 16 according to FIG. 1 (dashed line) to the gain 64 (dash-dotted line) that occurs in signal processing 8.

[0050] FIG. 4 shows a plurality of frequency-resolved curves 60a-m for the feedback tendency. These curves correspond, for example, to various individual measurements taken during the first use situation according to FIG. 2. In the frequency range up to approximately 3 kHz the individual curves 60a-m hardly differ from each other, and thus the variance of the different curve values at a given frequency is hardly worth mentioning, but from 3 kHz upwards the curves 60a-m drift noticeably apart. Particularly notably, in a narrow frequency range around 6 kHz, the individual curves differ by up to 30 dB. From 7 kHz upwards, the curves are almost uniform again.

[0051] Based on the curves 60a-m, a criticality measure 66 is ascertained analogously to the first criticality measure 36, third criticality measure 64 and fourth criticality measure 56. This is done by adding a correction term at each frequency f to the maximum value of 60m for the feedback tendency (dotted line), which monotonically depends on the variance of the individual values of the curves 60a-m at a given frequency f. Thus, for the high variance present just below 6 kHz, the criticality measure 66 (dashed line) is at a maximum.

[0052] The absolute values of the individual curves 60a-m in the range around 2 kHz are even higher than the maximum value 60m at approximately 4 kHz, but the criticality measure 66 nonetheless is greater than at 2 kHz due to the higher variance at 4 kHz. This takes account of the fact that over the entire range of possible values during the first use situation at 2 kHz, the stability of the system is higher than at 4 kHz, and as a result, it may be assumed that the ascertained maximum at 4 kHz does not necessarily correspond to the absolute possible maximum value, while the contrary is probably the case for 2 kHz due to the high stability at that frequency. Accordingly, the criticality measure is higher at 4 kHz.

[0053] From the criticality measure 66, frequency ranges 68 may now be identified for which acoustic feedback is particularly likely in the respective use situation, and which must accordingly be adapted to a hearing device parameter. To this end, the exceeding of a threshold value by the criticality measure 66 may be used as a criterion, and in a first approximation, 0 dBi.e. the limit for a critical gainmay be selected as the threshold value.

[0054] Although the invention was illustrated and described in greater detail by means of the preferred exemplary embodiment, this exemplary embodiment does not limit the invention. A person of ordinary skill in the art will be able to derive other variations therefrom, without departing from the invention's protected scope.

[0055] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0056] 1 Hearing device [0057] 2 Input transducer [0058] 4 Sound signal [0059] 6 Input signal [0060] 8 Signal processing [0061] 10 Output signal [0062] 12 Output transducer [0063] 14 Output sound signal [0064] 15 Acoustic coupling piece [0065] 16 Acoustic feedback path [0066] 18 Adaptive filter [0067] 20 Compensation signal [0068] 22 Error signal [0069] 30 First wearing situation [0070] 32 First use situation [0071] 34a-c Frequency-resolved curves [0072] 36 First criticality measure [0073] 38 Target [0074] 40 Hearing device parameters [0075] 42 Test mode [0076] 44a-c Frequency-resolved curves [0077] 46 Third criticality measure [0078] 50 Second wearing situation [0079] 54a-c Frequency-resolved curves [0080] 56 Fourth criticality measure [0081] 60 Feedback tendency [0082] 60a-m Frequency-resolved curves (for feedback tendency) [0083] 60m Maximum [0084] 62 Attenuation [0085] 64 Gain [0086] 66 Criticality measure [0087] 68 Frequency range