Hearing aid with sound impulse cancellation and associated method

Description

[0001] The present disclosure relates to a hearing device with sound impulse suppression and related method.BACKGROUND

[0002] Sound impulses with high sound pressure levels may be discomforting, painful or even damaging to users of a hearing device. In particular, hearing aid compressors utilize dynamic sound level compression with time constants that are sufficiently long to reduce distortion of temporal characteristics of speech, which however reduces the ability to compress sound impulses with high energy, in turn increasing the discomfort for a hearing aid user.

[0003] Document EP 2306754 A1 relates to a hearing aid comprising: a first microphone for provision of a first microphone input signal; a sound impulse suppression module configured for detecting a sound impulse in the first microphone input signal; a processor for processing the first microphone input signal, to obtain an electrical output signal; and a receiver for converting the electrical output signal to an audio output signal, wherein the sound impulse suppression module is configured to apply a detection scheme on the first microphone input signal and to reduce a gain applied to the first microphone input signal by the processor when a sound impulse is detected.

[0004] Document EP2980800 A1 relates to a method and system for robust noise level estimation comprising calculating an impulsive noise probability of the noise signal, the impulsive noise probability indicating a likelihood that the noise signal involves a short-period impulsive noise. The method also comprises determining a variable smoothing factor for noise level estimation based on the impulsive noise probability and smoothing the noise signal with the variable smoothing factor. The variable smoothing factor is increased as the impulsive noise probability is increased over time, and the variable smoothing factor is decreased as the impulsive noise probability is decreased over time.SUMMARY

[0005] There is a need for devices and methods overcoming or at least reducing the discomfort resulting from sound impulses.

[0006] Accordingly, a hearing device is disclosed, the hearing device comprising a first microphone for provision of a first microphone input signal; a sound impulse suppression module configured for detecting a sound impulse in the first microphone input signal; a processor for processing the first microphone input signal in a processing set of frequency bands to obtain an electrical output signal; and a receiver for converting the electrical output signal to an audio output signal. The sound impulse suppression module is configured to apply a detection scheme on the first microphone input signal, wherein the detection scheme defines a detection set of frequency bands, wherein the frequency bands of the detection set covers a part of the frequency bands of processing set, and wherein a sound impulse is detected based on the detection set of frequency bands.

[0007] Further, a method of operating a hearing device is provided, the hearing device comprising a processor configured to process a first microphone input signal from a first microphone in a processing set of frequency bands to obtain an electrical output signal, wherein the method comprises detecting a sound impulse in the microphone input signal; and reducing a gain applied to the first microphone input signal (or to a signal based on the first microphone input signal, such as a beamformed signal based on the first microphone input signal) in the processor when a sound impulse is detected, wherein detecting a sound impulse comprises applying a detection scheme on the first microphone input signal, wherein the detection scheme defines a detection set of frequency bands, wherein the detection set of frequency bands covers a part of the frequency bands of processing set, and wherein detecting a sound impulse is based on the detection set of frequency bands.

[0008] The present hearing devices and methods provide improved impulse suppression in a hearing device. For example, the present hearing devices can be tailored to suppress specific types of sound impulses. Further, the present disclosure provides a power and processing efficient impulse suppression, which is important considering the limited power and processing resources available in a hearing device.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other features and advantages of the present invention will become readily apparent to those skilled in the art by the following detailed description of exemplary embodiments thereof with reference to the attached drawings, in which: Fig. 1 schematically illustrates an exemplary hearing device, Fig. 2 is a power spectrum of frequency bands of a detection scheme, and Fig. 3 is a flowchart of an exemplary method. DETAILED DESCRIPTION

[0010] Various exemplary embodiments and details are described hereinafter, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described.

[0011] The hearing device may be a hearing aid, e.g. of the behind-the-ear (BTE) type, in-the-ear (ITE) type, in-the-canal (ITC) type, receiver-in-canal (RIC) type or receiver-in-the-ear (RITE) type. The hearing aid may be a binaural hearing aid.

[0012] The hearing device may be a hearing aid and the processor may be configured to compensate for hearing loss of a user.

[0013] The hearing device may be a headset, a headphone, an earphone, an ear defender, or an earmuff, such as an Ear-Hook, In-Ear, On-Ear, Over-the-Ear, Behind-the-Neck, Helmet, or Headguard.

[0014] The hearing device comprises a first microphone for provision of a first microphone input signal. The hearing device may comprise a second microphone for provision of a second microphone input signal. The hearing device may comprise J microphones for provision of J microphone signals, wherein J is an integer in the range from 1 to 10. In one or more exemplary hearing devices, the number J of microphones is two, three, four, five or more. The hearing device may comprise a third microphone for provision of a third microphone input signal.

[0015] The hearing device comprises a sound impulse suppression module. The sound impulse suppression module is configured for detecting a sound impulse in the first microphone input signal. The sound impulse suppression module is configured for operation in the frequency domain. The sound impulse suppression module may comprise an impulse detector optionally configured for operation in the frequency domain, e.g. utilizing a Fourier Transformation, such as the Discrete Fourier Transformation, the Fast Fourier Transformation, etc., for transforming the first microphone input signal into a frequency domain for detecting the sound impulse. The impulse detector may be configured for utilizing a warped frequency transformation, such as the Warped Fourier Transformation, the Warped Discrete Fourier Transformation, the Warped Fast Fourier Transformation, etc., for transforming the first microphone input signal into a warped frequency domain.

[0016] The warped frequency bands may correspond to the Bark frequency scale of the human ear.

[0017] The sound impulse suppression module may be configured for detecting a sound impulse in a second microphone input signal.

[0018] The hearing device comprises a processor for processing the first microphone input signal in a processing set, PFB, of frequency bands FP i , where i is an index from 1 to L, to obtain an electrical output signal. The processor may be configured to compensate for hearing loss of a user.

[0019] The processor may comprise a filter bank for filtering the first microphone input signal into the frequency bands FP 1 , FP 2 , ..., FP L , where the number L of frequency bands in the processing set PFB may be at least 10, such as 15, 17 or 24. In one or more exemplary hearing devices, the number L of frequency bands in the processing set PFB may be 20 or more, such as 64. In one or more exemplary hearing devices, the number L of frequency bands in the processing set PFB may be from 5 to 10.

[0020] Further, the hearing device comprises a receiver for converting the electrical output signal to an audio output signal.

[0021] The sound impulse suppression module is configured to apply a detection scheme, such as a first detection scheme and / or a second detection scheme, on the first microphone input signal.

[0022] A detection scheme defines a detection set DFB of frequency bands FD j , where j is an index from 1 to M, and a sound impulse is detected based on the detection set of frequency bands.

[0023] The frequency bands of the detection set cover a part of the frequency bands of the processing set. Thus, the frequency bands of the processing set cover frequencies that are not covered by the frequency bands of the detection set, and the sound impulse suppression module therefore operates on a reduced frequency range. Therefore, the required processing for impulse detection is reduced compared to a full-fetched sound impulse suppression based on the processing set of frequency bands.

[0024] In one or more exemplary hearing devices, the frequency bands of the detection set may be selected as a proper subset of the frequency bins of a DFT or FFT. In one or more exemplary hearing devices, the number M of frequency bands of the detection set may be less than K, where K is the number of available frequency bins of an FFT employed in the impulse detector / sound impulse suppression module.

[0025] The frequency bands FD j , j=1, ..., M of the detection set each have center frequencies denoted fd 0,j and bandwidths denoted BD j . The frequency bands FP i , i=1, ..., L of the detection set each have center frequencies denoted fp 0,i and bandwidths denoted BP i . In one or more hearing devices, the minimum center frequency of center frequencies fd 0,j , j=1, ..., M is larger than a first center frequency threshold FCTH. The first center frequency threshold FCTH may be larger than 500 Hz, such as larger than 1 kHz, e.g. about 2 kHz.

[0026] In one or more hearing devices, the maximum center frequency of center frequencies fd 0,j , j=1, ..., M is larger than a second center frequency threshold SCTH. The second center frequency threshold SCTH may be less than 6 kHz, such as less than 1 kHz, e.g. about 2 kHz. The average center frequency of fd 0,j , j=1, ..., M may be larger than 0.55*BP, such as larger than 0,6*BP, where BP is the bandwidth of the processor, typically about 8-12 kHz. The average center frequency of fd 0,j , j=1, ..., M may be less than 0.45*BP, such as less than 0,4*BP, where BP is the bandwidth of the processor, typically about 8-12 kHz. A high average center frequency is indicative of impulse detection in high-frequency bands and a low average center frequency is indicative of impulse detection in low-frequency bands.

[0027] The detection set of frequency bands may be a proper subset of the processing set of frequency bands.

[0028] A frequency band has a lower frequency f l and an upper frequency f u . The frequency bands FD 1 -FD M of the detection subset has lower frequencies denoted f l,j and upper frequencies denoted f u,j , where j = 1, ..., M.

[0029] The frequency bands of the detection set may have lower frequencies f l,1 , ..., f l,M above a first frequency threshold. In one or more exemplary hearing devices, the first frequency threshold FFTH may be larger than 1kHz, such as in the range from 1.5 kHz to 5 kHz, e.g. 3 kHz.

[0030] The frequency bands of the detection set may have upper frequencies f u,1 , ..., f u,M below a second frequency threshold. In one or more exemplary hearing devices, the second frequency threshold SFTH may be less than 6 kHz, such as in the range from 1 kHz to 5 kHz, e.g. 3 kHz.

[0031] The frequency bands of the detection set may be arranged within one or more frequency ranges including a first frequency range. The frequency bands of the detection set may be arranged within a first frequency range and a second frequency range, wherein the first frequency range and the second frequency range are separate frequency ranges. In one or more exemplary hearing devices, one or more frequency bands of the detection set are arranged within a first frequency range, e.g. from 100 Hz to 1 kHz and one or more frequency bands of the detection set are arranged within a second frequency range, e.g. from 3 kHz to 8 kHz.

[0032] In one or more exemplary hearing devices, the frequency bands of the detection set may be selected as a number of the frequency bins of a DFT or FFT. In one or more exemplary hearing devices, the number M of frequency bands of the detection set is less than K, where K is the number of available frequency bins of an FFT employed in the impulse detector / sound impulse suppression module. For an exemplary detection set, M-K>3.

[0033] The detection set DFB of frequency bands applied by the sound impulse suppression module may have less frequency bands than the processing set PFB of frequency bands. Thus, the number of frequency bands in the detection set may be lower than the number of frequency bands in the processing set of frequency bands. Reducing the number of frequency bands in the detection set provides a power efficient and yet reliable detection scheme, e.g. compared to monitoring all frequency bands of the processing set. In one or more exemplary hearing devices, PFB = {FP 1 , FP 2 , ..., FP L } and DFB = {FD 1 , FD 2 , ..., FD M }, where L is larger than 10, such as 15 or 17. Further, tailoring the frequency bands of the detection set DFB enables the hearing aid designer to ignore sound impulses in one or more frequency bands, e.g. in order to allow / not react on (suppress) sound impulses in one or more frequency bands, where the user actually would like to hear the sound impulses.

[0034] In one or more exemplary hearing devices, the processing set of frequency bands comprises L frequency bands and the detection set of frequency bands comprises M frequency bands, wherein L is larger than M. In one or more exemplary hearing devices, L-M is greater than or equal to 3. M may be 1, 2, 3, 4 or more. In one or more exemplary hearing devices, M is in the range from 5 to 20. In one or more exemplary hearing devices, L-M is greater than or equal to 1 or 2.

[0035] The number M of frequency bands in the detection set may be less than fourteen, such as less than twelve or less than ten. The number L of frequency bands in the processing set may be larger than four, e.g. larger than ten, such as larger than twelve or larger than fourteen.

[0036] The sound impulse suppression module may be configured to determine rise parameter(s) R j of the first microphone input signal in the frequency band(s) of the detection set. The sound impulse suppression module may be configured to detect a sound impulse based on the rise parameters.

[0037] A rise parameter R j is indicative of a power increase in the first microphone input signal in a frequency band FD j .

[0038] For example, where DFB = {FD 1 , FD 2 , ..., FD 12 }, the sound impulse suppression module determines twelve rise parameters R 1 -R 12 and detects a sound impulse based on the rise parameters R 1 -R 12 .

[0039] The rise parameters R j may be based on an instant power estimate and a reference power estimate of the first microphone input signal in the respective frequency bands.

[0040] The rise parameter(s) R j may be given as: R j = P j P _ ref j , where P j is an instant power estimate of frequency band FD j and P_ref j is a reference power estimate of the first microphone input signal in frequency band FD j .

[0041] In one or more exemplary hearing devices, the rise parameter R j may advantageously be implemented in the logarithmic domain, such as the log2 domain. The precision of the log2 is found to be sufficiently accurate, and the remaining part of the impulse detector could improve by having decision and threshold implemented in the logarithmic domain. Thus, rise parameter(s) R j may be given as: R j = log 2 P j − log 2 P _ ref j , where P j is an instant power estimate and P_ref j is a reference power estimate of the first microphone input signal in frequency band FD j .

[0042] The sound impulse suppression module may be configured to detect a sound impulse based on the number of rise parameters that has reached a respective rise threshold.

[0043] A rise threshold may be a common rise threshold TH for all frequency bands i.e. the same rise threshold may be applied to each of the frequency bands FD j .

[0044] In one or more exemplary hearing devices, a rise threshold TH j may be applied for each frequency band FD j . Rise thresholds TH j may be different for different frequency bands. For example, a rise threshold TH 7 for FD 7 may be different for the rise threshold TH 10 for FD 10 . The rise thresholds TH j may be defined in the log2 domain.

[0045] In one or more exemplary hearing devices, a rise threshold TH j may be applied for a plurality of groups of frequency band FD j . For example, a first rise threshold TH x may be applied to a first group of frequency bands FD j , such as for example FD 1 - FD 6 , and a second rise threshold TH y may be applied to a second group of frequency bands FD j such as for example FD 7 -FD 12 . In one or more exemplary hearing devices, a first rise threshold TH x may be applied to a first group of frequency bands FD j , such as for example FD 1 - FD 3 and FD 8 and FD 10 - FD 12 , and a second rise threshold TH y may be applied to a second group of frequency bands FD j such as for example FD 4 - FD 7 and FD 11 .

[0046] Thus, the sound impulse suppression module may be configured to determine if rise parameter R j have reached respective rise threshold TH j for the frequency bands in the detection set DFB, i.e. if R j ≥ TH j for FD j . In one or more exemplary hearing devices, the rise threshold of one frequency band in the detection set is different from the rise threshold of another frequency band in the detection set, e.g. TH 8 ≠ TH 10 .

[0047] In one or more exemplary hearing devices, a sound impulse may be detected if the number of rise parameters that has reached a respective rise threshold is larger than a rise number threshold. For example where DFB = {FD 1 , FD 2 , ..., FD 12 }, a sound impulse may be detected if more than RNTH=8 rise parameters out of R 1 -R 12 have reached their respective rise threshold TH 1 -TH 12 , where RNTH is the rise number threshold.

[0048] The detection scheme may define rise thresholds for the frequency bands of the detection set. The detection scheme may define the rise number threshold.

[0049] The sound impulse suppression module may be configured to determine a rise parameter if the instant power estimate of a frequency band in the detection set of frequency bands is greater than the reference power estimate of the frequency band.

[0050] In one or more exemplary hearing devices, the rise parameter is determined if the instant power estimate is greater than the reference power estimate plus a power estimate threshold PETH j .

[0051] The reference power estimate may be a smoothed power estimate based on the instant power estimate and a smoothing parameter. In one or more exemplary hearing devices, the reference power estimate may be base d on power estimates in a reference time period of at least 400 ms, such as at least 1 s.

[0052] The reference power estimate may be calculated as an average over a plurality of previous instant power estimates. The average may be an average over previous instant power estimates over time.

[0053] The instant power estimate P i may be based on a single input block of samples. The instant power estimate P i may be based on a number of input blocks of samples, e.g. wherein the number of input blocks is less than 5. An input block has a time length T block given as: T block = N ⋅ 1 f s ′ where N is the size of a discrete Fourier Transform DFT or a fast Fourier Transform FFT and f s is the sampling frequency. In one or more exemplary hearing devices, T block is in the range from 1-2 ms, e.g. about 1.5 ms. Thus, the number of input block samples used for determining the instant power estimate is kept low to enable detection of sound impulses with very short rise times.

[0054] The hearing device may comprise a broadband power estimator, and the sound impulse suppression module may be configured to detect a sound impulse based on a broadband power estimate from the broadband power estimator, e.g. if the broadband power estimate is larger than a broadband power threshold, BPTH. The detection scheme may define the broadband power threshold, BPTH. The sound impulse suppression module may be configured to apply the detection scheme based on the broadband power estimate. For example, the sound impulse suppression module may be configured to apply a first detection scheme if the broadband power estimate is in a first range, e.g. indicative of low broadband power, and / or the sound impulse suppression module may be configured to apply a second detection scheme different from the first detection scheme if the broadband power estimate is in a second range, e.g. indicative of high broadband power.

[0055] The sound impulse suppression module may be configured to reduce a gain applied to the first microphone input signal (or to a signal based on the first microphone input signal, such as a beamformed signal based on the first microphone input signal) by the processor when a sound impulse is detected. For example, the sound impulse suppression module may be configured to reduce the gain in frequency bands where the rise parameter R j has reached the rise threshold TH j for the respective frequency bands. For example, the gain G 10 applied to the first microphone input signal in FP 10 may be reduced if R 10 ≥ TH 10 .

[0056] The sound impulse suppression module may be configured to determine one or more gain reductions and transmit the one or more gain reductions to the processor. The sound impulse suppression module may be configured to determine one or more gain reductions based on the rise parameters R j and / or gain parameters of frequency bands FP 1 -FP L .

[0057] The gain reduction for one frequency band may be different from the gain reduction of another frequency band. For example, the gain reduction GR 10 for FP 10 may be different from the gain reduction GR 12 for FP 12 . The sound impulse suppression module may be configured to determine a first gain reduction for a first subset of frequency bands, e.g. FP 6 -FP 9 , in PFB and a second gain reduction for a second subset, e.g. FP 10 -FP 17 , of frequency bands in PFB. The sound impulse suppression module may be configured to determine gain reductions GR 1 -GR L for all or some of frequency bands FP 1 -FP L in PFB.

[0058] The hearing device may comprise a sound environment detector for classifying the sound environment into a predetermined set of sound environments. The set of sound environments may comprise a first sound environment, a second sound environment and optionally a third sound environment. The sound impulse suppression module may be configured to apply the detection scheme based on the sound environment. For example, the sound impulse suppression module may be configured to apply a first detection scheme if the sound environment is classified as a first sound environment, and the sound impulse suppression module may be configured to apply a second detection scheme different from the first detection scheme if the sound environment is classified as a second sound environment.

[0059] Further, the present disclosure relates to a method of operating a hearing device comprising a processor configured to process a first microphone input signal from a first microphone in a processing set of frequency bands to obtain an electrical output signal, the hearing device comprising a sound impulse suppression module.

[0060] The method comprises detecting a sound impulse in the microphone input signal, e.g. with an impulse detector of the sound impulse suppression module.

[0061] The method comprises reducing a gain applied to the first microphone input signal in the processor, e.g. with a gain reduction module of the sound impulse suppression module, when a sound impulse is detected,

[0062] In the method, detecting a sound impulse comprises applying a detection scheme on the first microphone input signal, e.g. in the impulse detector, wherein the detection scheme optionally defines a detection set of frequency bands, wherein the detection set of frequency bands covers a part of the processing set of frequency bands, and wherein detecting a sound impulse is based on the detection set of frequency bands.

[0063] The method may comprise determining rise parameters of the first microphone input signal in the frequency bands of the detection set, wherein a rise parameter is indicative of a power increase in the first microphone input signal in a frequency band, and wherein detecting a sound impulse is based on the rise parameters.

[0064] In the method, detecting a sound impulse may be based on the number of rise parameters that has reached a respective rise threshold.

[0065] In the method, a sound impulse may be detected if the number of rise parameters that has reached a respective rise threshold is larger than a rise number threshold.

[0066] In the method, detecting a sound impulse may be based on a broadband power estimate from a broadband power estimator of the hearing device.

[0067] The method may comprise reducing a gain applied to the first microphone input signal (or to a signal based on the first microphone input signal, such as a beamformed signal based on the first microphone input signal) by the processor when a sound impulse is detected. The method may comprise determining one or more gain reductions and transmitting the one or more gain reductions to the processor. Determining one or more gain reductions may be based on the rise parameters R i .

[0068] In one or more exemplary methods, the gain reduction GR i for one frequency band FP i is different from the gain reduction of another frequency band. For example, the gain reduction GR 10 for FP 10 may be different from the gain reduction GR 12 for FP 12 . The method may comprise determining a first gain reduction for a first subset of frequency bands in PFB and a second gain reduction for a second subset of frequency bands in PFB.

[0069] In the method, the number of frequency bands in the detection set may be less than fourteen, and the number of frequency bands in the processing set may be larger than fourteen.

[0070] The method may comprise classifying the sound environment into a predetermined set of sound environments, and optionally applying a first detection scheme if the sound environment is classified as a first sound environment. The method may comprise applying a second detection scheme different from the first detection scheme if the sound environment is classified as a second sound environment.

[0071] Table 1 illustrates six exemplary detection schemes DS1-DS6 with associated parameters, where rise thresholds are given in the logarithmic domain. Further, exemplary processing frequency bands PFB associated with the processor are also given. Table 1: Exemplary detection schemes DS1-DS6. DS1DS2DS3DS4DS5DS6DFBFD 1 -FD 12 FD 1 -FD 14 FD 1 FD 1 -FD 12 FD 1 -FD 4 FD 1 -FD 5 PFBFP 1 -FP 17 FP 1 -FP 17 FP 1 -FP 17 FP 1 -FP 17 FP 1 -FP 9 FP 1 -FP 24 RNTH8511032TH j (j=1-12) =16 dBTH j (j=1-14) =16 dBTH 1 =20 dBTH j (j=1-7) = 16 dBTH 1 = 2 dBTH 1 = 1 dBTH 2 = 6 dBTH 2 = 2 dBTH j (j=8-12) = 9 dBTH j (j=3-4) = 9 dBTH 3 = 3 dBTH 4 = 4 dBTH 5 = 5 dBfd o,j (j=1-12) > 2 kHzfd o,j (j=1-14) < 9 kHzfd o,1 > 5 kHzfd o,j (j=1-12) > 1 kHzfd o,j (j=1-5) > 6 kHzFFTH3 kHz6 kHz3 kHz500 Hz6 kHzSFTH9 kHz4 kHzBPTH80 dB80 dB90 dB85 dB75 dB80 dB

[0072] Fig. 1 shows an exemplary hearing device. The hearing device 2 comprises a first microphone 4 for provision of a first microphone input signal 6; a sound impulse suppression module 8 configured for detecting a sound impulse in the first microphone input signal 6; a processor 10 for processing the first microphone input signal in a processing set of frequency bands with 17 frequency bands to obtain an electrical output signal 12; and a receiver 14 for converting the electrical output signal 12 to an audio output signal. The sound impulse suppression module 8 is configured to apply a detection scheme on the first microphone input signal, e.g. with impulse detector 16, wherein the detection scheme defines a detection set of frequency bands, and wherein a sound impulse is detected in impulse detector 16 based on the detection set of frequency bands. The frequency bands of the detection set covers a part of the frequency bands of the processing set and the number M of frequency bands in the detection set is less than the number L of frequency bands in the processing set. Further, the hearing device comprises a sound environment detector 18 for classifying the sound environment into a predetermined set of sound environments. The resulting sound environment SE of the sound environment classification is transmitted to the sound impulse suppression module 8. The sound impulse suppression module is optionally configured to apply the detection scheme based on the sound environment. For example, the sound impulse suppression module 8 is configured to apply a first detection scheme, e.g. DS1, if the sound environment is classified as a first sound environment, and the sound impulse suppression module 8 is configured to apply a second detection scheme, e.g. DS2, different from the first detection scheme if the sound environment is classified as a second sound environment. The processor feeds broadband power estimate BPE to the sound impulse suppression module.

[0073] The sound impulse suppression module is configured to apply a detection scheme, e.g. DS1, on the first microphone input signal, wherein the detection scheme defines a detection set of frequency bands, wherein the frequency bands of the detection set covers a part of the frequency bands of the processing set, and wherein a sound impulse is detected based on the detection set of frequency bands. In the detection scheme DS1, the frequency bands FD 1 -FD 12 are selected as the 6 th< to the 17 th< frequency bins of an FFT with a 32-sample window length and a sampling frequency of in the range from 20-22 kHz. Thus, the frequency bands of the detection set have lower frequencies above a first frequency threshold of 2 kHz. Other sampling frequencies may be applied in the sound impulse suppression module.

[0074] The sound impulse suppression module 8 is configured to determine rise parameters (log domain) of the first microphone input signal in the frequency bands of the detection set, wherein a rise parameter is indicative of a power increase in the first microphone input signal in a frequency band, and wherein the sound impulse suppression module is configured to detect a sound impulse based on the rise parameters. The sound impulse suppression module 8 detects a sound impulse if the number of rise parameters that has reached a respective rise threshold is larger than a rise number threshold of 8. The rise thresholds are optionally defined by the detection scheme, i.e. the rise thresholds may change with change of detection scheme. In detection scheme DS1, the rise thresholds for the respective frequency bands are 16 db. The sound impulse suppression module 8 is configured to reduce a gain applied to the first microphone input signal by the processor when a sound impulse is detected by determining and transmitting gain reduction vector with gain reductions GR i , i=1, ..., L to the processor 10. The second detection scheme may be DS2, where different rise thresholds THj are applied in DS2.

[0075] Fig. 2 illustrates a power spectrum of frequency bands FD 1 -FD 12 of detection scheme DS1, where FD 1 is the 6 th< frequency bin of a 32-sample window FFT, FD 2 is the 7 th< frequency bin, etc. Thus, the detection set is a proper subset of frequency bins 1-17 of the FFT applied in impulse detector 16. The instant power estimates P 1 -P 12 of the frequency bands FD 1 -FD 12 are all above the reference power estimates and P_ref 1 -P_ref 12 . The broadband power estimate is 82 dB, which is larger than BPTH=80 dB of DS1. Further, more than RNTH=8 of the rise parameters R 1 -R 12 have respectively reached TH 1 -TH 12 =16 dB. Therefore, a sound impulse is detected and a gain reduction vector with gain reductions GR 1 -GR 17 is determined and fed to processor, such that the sound impulse is suppressed.

[0076] Fig. 3 is a flowchart of an exemplary method of operating a hearing device comprising a processor configured to process a first microphone input signal from a first microphone in a processing set of frequency bands to obtain an electrical output signal. The method 100 comprises detecting 102 a sound impulse in the microphone input signal; and reducing 104 a gain applied to the first microphone input signal in the processor when a sound impulse is detected. Detecting 102 a sound impulse comprises applying 106 a detection scheme on the first microphone input signal, wherein the detection scheme defines a detection set of frequency bands, wherein the detection set of frequency bands covers a part of the frequency bands of the processing set, and wherein detecting a sound impulse is based on the detection set of frequency bands. The method 100 comprises determining 108 rise parameters of the first microphone input signal in the frequency bands of the detection set, wherein a rise parameter is indicative of a power increase in the first microphone input signal in a frequency band. Detecting 102 a sound impulse is based on the rise parameters and the number of rise parameters that has reached a respective rise threshold, wherein a sound impulse is detected if the number of rise parameters that has reached a respective rise threshold is larger than a rise number threshold. Further, detecting 102 a sound impulse is based on a broadband power estimate from a broadband power estimator of the hearing device.

[0077] Reducing 104 a gain comprises determining 110 one or more gain reductions and transmitting 112 the one or more gain reductions to the processor. Determining one or more gain reductions are based on the rise parameters R i and / or the broadband power estimate. The method 100 comprises classifying 114 the sound environment into a predetermined set of sound environments, and applying the detection scheme accordingly by applying a first detection scheme if the sound environment is classified as a first sound environment and applying a second detection scheme different from the first detection scheme if the sound environment is classified as a second sound environment.

[0078] Although particular features have been shown and described, it will be understood that they are not intended to limit the claimed invention, and it will be made obvious to those skilled in the art that various changes and modifications may be made without departing from the scope of the claimed invention. The specification and drawings are, accordingly to be regarded in an illustrative rather than restrictive sense.LIST OF REFERENCES

[0079] 2hearing device 4first microphone 6first microphone input signal 8sound impulse suppression module 10processor 12electrical output signal 14receiver 16impulse detector 18sound environment detector 100method of operating a hearing device 102detecting a sound impulse in the microphone input signal 104reducing a gain 106applying a detection scheme on the first microphone input signal 108determining rise parameters 110determining one or more gain reductions 112transmitting the one or more gain reductions to the processor 114classifying the sound environment

Claims

1. A hearing device (2) comprising: - a first microphone (4) for provision of a first microphone input signal (6); - a sound impulse suppression module (8) configured for detecting a sound impulse in the first microphone input signal; - a processor (10) for processing the first microphone input signal (6) in a processing set of frequency bands to obtain an electrical output signal (12); and - a receiver (14) for converting the electrical output signal to an audio output signal, wherein the sound impulse suppression module (8) is configured to apply a detection scheme on the first microphone input signal (6), wherein the detection scheme defines a detection set of frequency bands, wherein the frequency bands of the detection set cover a part of the frequency bands of the processing set, and wherein a sound impulse is detected based on the detection set of frequency bands.

2. Hearing device according to claim 1, wherein the frequency bands of the detection set have each a lower frequency, the lower frequencies being above a first frequency threshold.

3. Hearing device according to any of claims 1-2, wherein the frequency bands of the detection set have each an upper frequency, the upper frequencies being below a second frequency threshold.

4. Hearing device according to any of claims 1-3, wherein the frequency bands of the detection set are arranged within one or more frequency ranges including a first frequency range.

5. Hearing device according to any of claims 1-4, wherein the processing set of frequency bands comprises L frequency bands and the detection set of frequency bands comprises M frequency bands, and wherein L-M is greater than or equal to 3.

6. Hearing device according to any of claims 1-5, wherein the sound impulse suppression module is configured to determine rise parameters of the first microphone input signal in the frequency bands of the detection set, wherein a rise parameter is indicative of a power increase in the first microphone input signal in a frequency band, and wherein the sound impulse suppression module is configured to detect a sound impulse based on the rise parameters.

7. Hearing device according to claim 6, wherein the sound impulse suppression module is configured to detect a sound impulse based on the number of rise parameters that has reached a respective rise threshold.

8. Hearing device according to claim 7, wherein a sound impulse is detected if the number of rise parameters that has reached a respective rise threshold is larger than a rise number threshold.

9. Hearing device according to any of claims 7-8, wherein the detection scheme defines rise thresholds for the frequency bands of the detection set.

10. Hearing device according to any of claims 6-9, wherein the rise threshold of one frequency band in the detection set is different from the rise threshold of another frequency band in the detection set.

11. Hearing device according to any of claims 6-10, wherein the rise parameters are based on an instant power estimate and a reference power estimate of the first microphone input signal in the respective frequency bands.

12. Hearing device according to any of claims 1-11, wherein hearing device comprises a broadband power estimator, and wherein the sound impulse suppression module is configured to detect a sound impulse based on a broadband power estimate from the broadband power estimator.

13. Hearing device according to any of claims 1-12, wherein the sound impulse suppression module is configured to reduce a gain applied to the first microphone input signal by the processor when a sound impulse is detected.

14. Hearing device according to any of claims 1-14, wherein the hearing device comprises a sound environment detector for classifying the sound environment into a predetermined set of sound environments, wherein the sound impulse suppression module is configured to apply a first detection scheme if the sound environment is classified as a first sound environment, and wherein the sound impulse suppression module is configured to apply a second detection scheme different from the first detection scheme if the sound environment is classified as a second sound environment.

15. A method (100) of operating a hearing device comprising a processor configured to process a first microphone input signal from a first microphone in a processing set of frequency bands to obtain an electrical output signal, wherein the method (100) comprises - detecting (102) a sound impulse in the microphone input signal; and - reducing (104) a gain applied to the first microphone input signal in the processor when a sound impulse is detected, wherein detecting (102) a sound impulse comprises applying (106) a detection scheme on the first microphone input signal, wherein the detection scheme defines a detection set of frequency bands, wherein the detection set of frequency bands covers a part of the frequency bands of the processing set, and wherein detecting a sound impulse is based on the detection set of frequency bands.