Hearing aid and procedure for operating such a

Abstract

Hearing aid (2), - which has at least one microphone (4) designed to receive sound signals (6) within a total frequency range (Fg) and convert them into an input signal (8), - which includes signal processing (10) for processing the input signal (8) within a lower frequency range (Fu), which is part of the total frequency range (Fg), - which has a detector (12) for detecting a disturbance noise (14) which has frequency components both within the lower frequency range (Fu) and outside of it, namely in an upper frequency range (Fo) above the lower frequency range (Fu), - which is designed such that the detector (12) detects the noise (14) based on its frequency component in the upper frequency range (Fo), wherein the lower frequency range (Fu) has an upper limit (26) of 12 kHz and / or wherein the upper frequency range (Fo) has a lower limit (28) of 12 kHz and an upper limit (30) of 16 kHz.

Description

[0001] The invention relates to a hearing aid and a method for operating such a hearing aid.

[0002] A hearing aid generally serves to deliver sound signals to its user. Specifically, a hearing aid designed to serve a user with a hearing loss is designed to receive sound signals from the environment, process them, and then output them in a modified form (i.e., regularly amplified) that at least partially compensates for the hearing loss.

[0003] In a given environment, both useful noise and background noise regularly occur. The former should be reproduced as clearly as possible for the user, while the latter should be suppressed as comprehensively as possible in order to improve the operation of the hearing aid and its benefit for the user. The effective suppression of background noise, however, requires the most effective detection of this background noise. Basically, there are different types of background noise, each of which is difficult to detect. Background noise differs, for example, in its bandwidth, amplitude and / or position in an overall frequency spectrum that is picked up by the hearing aid. Examples of different types of background noise are accordingly stationary background noise (i.e. narrowband and with little temporal variability), non-stationary and specifically transient and / or impulsive background noise (i.e.Broadband noise (i.e., broadband with high temporal variability), loud noise (i.e., with high amplitude), quiet noise (i.e., with low amplitude), high-frequency noise (with predominantly high frequency components), and low-frequency noise (with predominantly low frequency components). Examples of non-transient noise include stationary noise, e.g., a fan, or disturbing music or speech in the background, typically described by the term "cocktail party."

[0004] When using a hearing aid, the suppression of background noise, especially transient and / or impulsive noise, depends on its reliable detection. A hearing aid typically operates within a specific frequency range, the so-called operating range, in which the input signal is modified to adapt to the user. The operating range is typically only a sub-range of the acoustic frequency spectrum, which is specifically defined as the frequency range from 20 Hz to 20 kHz. This limitation to a sub-range of the acoustic frequency spectrum is typically due to the technical constraints of the hearing aid, as it cannot usually process arbitrarily high frequencies.

[0005] In the working area, noise is detected, for example, by identifying particularly loud frequency components, i.e., those with a specified minimum amplitude, as noise. For example, noise is detected by detecting that the minimum amplitude is exceeded in one or more frequency ranges. To suppress the noise, the hearing aid's amplification is then reduced in these frequency ranges, so that the noise is then amplified less than useful noise in other frequency ranges.

[0006] However, the detection of background noises with a comparatively low amplitude, i.e., an amplitude comparable to or lower than the possible or usual amplitude of useful noise, is problematic. Such background noises are also referred to as "quiet background noises," "low-volume background noises," or "soft background noises." These quiet background noises are not detected or are only poorly detected by a detector, which requires a predetermined minimum amplitude to be exceeded for detection. The minimum amplitude is expediently selected to be high enough to minimize interference with useful noises, especially speech. Speech, for example, regularly also has transient and / or impulsive components, but represents useful noise and not background noise, and should therefore be preserved. The detector can therefore ultimately only detect background noises above a certain volume, i.e.,The minimum amplitude cannot be set arbitrarily low. Thus, the detector has difficulty detecting background noise with a comparatively low amplitude, especially an amplitude in the range of typical speech amplitudes. Accordingly, noise suppression creates a conflict of objectives between minimizing the impact of false detection on useful sounds, especially speech, on the one hand, and suppressing even quiet background noise, on the other.

[0007] Various hearing aids are described in US 2013 / 0 156 208 A1, EP 3 793 209 A1 and DE 10 2015 204 253 A1.

[0008] Against this background, one object of the invention is to improve the detection of background noise during operation of a hearing aid. In particular, the detection of quiet background noise is to be improved. To this end, an improved hearing aid and an improved method for operating a hearing aid are to be provided.

[0009] The object is achieved according to the invention by a hearing aid having the features of claim 1 and by a method having the features of claim 12. Advantageous embodiments, refinements, and variants are the subject of the dependent claims. The statements made in connection with the hearing aid also apply mutatis mutandis to the method. If steps of the method are specified below, preferred embodiments for the hearing aid result from the fact that the hearing aid is designed to perform one or more of these steps, in particular by means of a control unit that is part of the hearing aid.

[0010] A key idea of ​​the invention is, in particular, to detect an interference noise in a frequency range in which the conflicting objectives when designing a detector for the interference noise are resolved by the fact that useful noise is not present or is present only to a small extent there. This advantageously allows a lower minimum amplitude to be used for detection than in a frequency range in which useful noise is expected, without significantly increasing the risk of false detections. In this way, even quiet interference noises are then better detected, at least those quiet interference noises which have frequency components in the said frequency range. This is especially the case for broadband interference noises, in particular transient and / or pulse-like interference noises which regularly have frequency components in an upper frequency range outside the operating range of a hearing aid and / or outside a speech frequency range.

[0011] Therefore, a hearing aid according to the invention has at least one microphone which is designed to record sound signals within a total frequency range and convert them into an input signal. The hearing aid also has signal processing for processing the input signal within a lower frequency range which is part of the total frequency range. Thus, the hearing aid has an operating range which contains at least and preferably exclusively the lower frequency range. The hearing aid also has a detector for detecting an interference noise which has frequency components both within the lower frequency range and outside it, namely in an upper frequency range above the lower frequency range. The upper frequency range preferably follows directly on from the lower frequency range, but this is not mandatory.Furthermore, the hearing aid is designed so that the detector detects the background noise based on its frequency component in the upper frequency range. This, in particular, implements the core concept described above. Overall, the hearing aid is thus designed to detect background noise during operation.

[0012] For the sake of simplicity, the term "noise detection" is used here. However, more precisely, it means that an interference signal is detected in the input signal, resulting from an acoustic noise that is part of the ambient sound signals. As a result, an ambient noise is detected.

[0013] In particular, the upper frequency range and the lower frequency range do not overlap. The upper frequency range is preferably not part of the operating range, but this is not mandatory, so that a design is also possible and suitable in which the operating range also contains the upper frequency range in whole or in part. What is more important is that the upper frequency range is characterized by the fact that less useful noise is present and / or to be expected in it than in the lower frequency range. In other words: in the upper frequency range, the SNR (signal-to-noise ratio), especially for the aforementioned quiet noises, is higher than in the lower frequency range (when considering the SNR, the noise in question is the "signal" and all other noises and noises constitute the "noise").Outside the lower frequency range, the proportion of speech is also regularly particularly low, so that false detections are efficiently reduced.

[0014] The invention is based in particular on the consideration that sound signals in general, and background noise in particular, are not limited to the operating range of the hearing aid, but can also lie outside of it while still remaining within the acoustic frequency spectrum mentioned above (defined from 20 Hz to 20 kHz). Transient and / or impulsive background noise, in particular, is broadband and thus spans a broad frequency range, thus also having high-frequency components that regularly lie outside the operating range (the terms "component" and "frequency component" are generally considered equivalent and used interchangeably). Background noise is referred to as broadband in particular when the associated frequencies span a frequency range of at least one octave.The detection of such background noise is particularly unreliable when detected at low frequencies, especially in the operating range of the hearing aid, where other stationary and non-stationary background noises are often present, which are often louder, i.e., have a higher amplitude. In addition, non-stationary components of speech can also lead to false detections, i.e., speech that is actually useful sound is mistakenly detected as background noise.

[0015] However, it has been observed that the amplitude of high-frequency noise (i.e., noise with a high-frequency component) is often lower than the amplitude of low-frequency noise, i.e., noise that typically lies within the working area. For example, in a restaurant or canteen, cutlery and dishes that bang together produce a clinking noise (also known as a "cling-clang sound"). This is a quiet, transient, and / or impulsive noise and also has a high-frequency component that usually lies outside the working area. Such noise, in particular, is now better detected using the hearing aid according to the invention, since even quiet noises in the upper frequency range are detected.The risk of false detections is significantly reduced because no or only little useful noise is to be expected in the upper frequency range, as this is predominantly or exclusively in the lower frequency range.

[0016] A particular advantage of the invention is that quiet, transient, and / or impulsive noises are more easily detected. This results from their detection by monitoring specifically the upper frequency range. Transient and / or impulsive noises are thus detected based on their frequency component outside the lower frequency range, thus avoiding the problems described when detecting them within this lower frequency range. This takes advantage of the fact that the noise is broadband and has frequency components in both the lower and upper frequency ranges.

[0017] Suppression of the noise is preferably carried out by means of signal processing and then, if necessary, only within the lower frequency range and not necessarily in the upper frequency range. It is assumed that the noise detected in the upper frequency range is correspondingly broadband and extends into the lower frequency range. Which frequency components in the lower frequency range are expediently suppressed when noise is detected in the upper frequency range is determined in advance, for example, in experiments or estimated based on typical bandwidths of noise which also contain components in the upper frequency range. A design is also suitable in which suppression simply takes place over a predefined frequency range within the lower frequency range, without actual knowledge as to whether this actually includes the noise.This utilizes the knowledge that the noise has a broad frequency spectrum and only lasts for a short time, making it very likely that it lies within the predefined frequency range. The predefined frequency range is, for example, 1 kHz to 5 kHz, starting at an upper limit of the lower frequency range and extending into this range. A suitable embodiment involves suppressing the noise by averaging the input signal overall over a specific period of time, e.g., 1 s to 5 s, and thereby smoothing it. However, the suppression of the noise is not the focus here; rather, the objective is to detect the noise as reliably as possible.

[0018] Another advantageous embodiment is one in which, in addition to the detector already mentioned (first detector), a further, second detector, e.g. a pulse detector, monitors the lower frequency range and then the triggering of this second detector is required as an additional criterion for suppression in order to ensure that a corresponding interference noise is actually present. Suppression then only occurs, for example, if a transient and / or pulse-like interference noise is detected both by the first detector in the upper frequency range and by the second detector in the lower frequency range. For this detector, the lower frequency range is suitably divided more coarsely than for signal processing, e.g. into just two frequency bands, for example a first frequency band from 100 Hz to 1000 Hz and a second frequency band from 1000 Hz to 12 kHz.

[0019] The hearing aid is preferably used to provide hearing-impaired users, i.e., users with a hearing deficit. For this purpose, the hearing aid has the aforementioned microphone, which picks up sound signals from the environment and generates an electrical input signal. This is fed to the aforementioned signal processing unit for processing. The signal processing unit is preferably part of a control unit of the hearing aid. The processing is carried out in particular on the basis of an individual audiogram of the user, which is assigned to the hearing aid, so that an individual hearing deficit of the user is compensated. Accordingly, the processing is preferably amplification. The signal processing unit produces an electrical output signal, which is then output to the user via an earpiece of the hearing aid, e.g., again as a sound signal, which is generated by the earpiece from the output signal.

[0020] Alternatively, the hearing aid is simply a headphone and then preferably has noise cancellation for the targeted suppression of background noise, which accordingly benefits from the improved detection of background noise.

[0021] The exact design of the detector is not initially relevant; what is more important is that it operates in the upper frequency range and searches for interference there. In principle, a conventional detector that would otherwise be used in the lower frequency range but now monitors the upper frequency range instead is suitable. Limiting the detector to the upper frequency range can be achieved, for example, by monitoring the upper frequency range exclusively or by only feeding the upper frequency range to the detector.

[0022] In a suitable embodiment, the hearing aid has a filter bank which divides the input signal into several channels, each of which is assigned to a frequency band. The filter bank is either integrated into the signal processing or formed separately from it. The filter bank has a large number of channels, in particular at least three, but typically a double-digit number. A first subset of the channels then forms the lower frequency range, and a second, different subset of the channels forms the upper frequency range, which is then fed to the detector. Independently of this, a filter bank is also advantageous for suppressing background noise, because the amplification can then be specifically adjusted in each individual channel, so that precisely those components which belong to a background noise are specifically reduced.A design is also possible in which the filter bank is limited to the lower frequency range and the upper frequency range is passed past the filter bank to the detector.

[0023] The detector is expediently a pulse detector, preferably a gradient-based pulse detector. A gradient-based pulse detector is particularly characterized by the fact that it detects transient and / or pulse-like noise based on a specific temporal increase in amplitude. In a suitable embodiment, the detector is designed as a level detector and thus detects the noise as such if its amplitude in the upper frequency range exceeds a minimum amplitude. The minimum amplitude depends on the individual preference and hearing impairment of the user and can be conveniently adjusted by the user. The detector thus triggers when the minimum amplitude in the upper frequency range is exceeded, thereby detecting a noise. The minimum amplitude is selected to be lower (e.g., half as large) than the minimum amplitude that would be selected for a detector monitoring the lower frequency range.

[0024] Alternatively or additionally, the detector is suitably designed as a gradient detector and thus detects the noise as such if its amplitude in the upper frequency range undergoes a minimum change during a predefined time interval. The gradient detector therefore monitors how much the amplitude changes (e.g. increases) over a predefined time interval, so that the detector only triggers if the amplitude undergoes at least a minimum change (i.e. a minimum amplitude change) during this predefined time interval. The predefined time interval depends in particular on a sampling rate for the input signal in the hearing aid and is, for example, in the range of 1 ms to 20 ms. The minimum change is just as individual as the minimum amplitude; the above statements apply analogously.

[0025] A suitable embodiment is one in which the detector is alternatively or additionally designed as its wavelet detector and thus recognizes the noise as such based on its spectral shape. The spectral shape is in particular the frequency-dependent amplitude curve of the noise. To detect the noise, a wavelet is specified which is an ideal form of the spectral shape and which is then compared with the actual noise, in particular by correlating the wavelet with the noise. The more the wavelet correlates with the noise, the more the noise corresponds to the wavelet. This is basically similar to an image comparison. In this way, specific noises whose spectral shape is generally known can be specifically searched for and detected. A simple pulse, for example, is used as a wavelet.

[0026] A second detector for the lower frequency range is not necessarily used in addition in this case, but is advantageous in addition to the first detector for the upper frequency range described here, e.g. to detect narrowband noise in the lower frequency range, which is not possible with the detector described here. Accordingly, the second detector for the lower frequency range, when configured as a level detector, then has a higher minimum amplitude than the detector for the upper frequency range. Due to the problem described at the beginning, to detect noise in the lower frequency range, a minimum amplitude is required which is greater than the usual or maximum achievable amplitude of useful noise in the lower frequency range.Since there is little or no useful noise in the upper frequency range, a correspondingly lower minimum amplitude is possible and advantageous, as even quiet background noises can be better detected. Furthermore, the statements regarding the first detector also apply analogously to the optional second detector.

[0027] As already indicated, the noise detectable by the detector is preferably transient and / or impulsive. Such noise is broadband and thus regularly has components in the upper frequency range (and typically also in the lower frequency range), thus being detectable by the detector in those frequencies. At the same time, such noise is often quiet, meaning it is so quiet that it is not necessarily reliably detectable in the lower frequency range.

[0028] In an advantageous embodiment, the noise is or will be generated by clinking crockery and / or cutlery. This generation mechanism results in a specific frequency spectrum for the noise, i.e., the noise exhibits a characteristic profile in the frequency domain, namely a broad spectrum and a low amplitude, because the noise is a quiet, transient, and / or pulse-like noise. The characteristic profile in the frequency domain was already mentioned above in connection with a wavelet detector and referred to there as the spectral shape; both terms are equivalent.

[0029] In detail, however, the profile (i.e., the spectral shape) of the noise is of secondary importance; more important is the impulsive nature of the noise. Such noise is often very loud and yet difficult to detect, since other transient and / or impulsive noises occur in the frequency range of a hearing aid (e.g., 100 Hz to 10 kHz). These are not noise but rather useful noises (e.g., plosives in speech) and should not be suppressed. Therefore, it is primarily important to distinguish between intentional and unwanted transient and / or impulsive noises, i.e., between transient and / or impulsive useful noises on the one hand, and transient and / or impulsive noises on the other.

[0030] As already mentioned above, the upper frequency range is preferably not part of the operating range of the hearing aid. For this purpose, in a suitable embodiment, the lower frequency range is an operating range of the signal processing, so that the processing of the input signal by the signal processing is limited to the lower frequency range. In particular, the operating range and the lower frequency range are identical. The processing is preferably amplification. The signal processing therefore does not process, preferably amplifies, the upper frequency range; this is only used for the detector and possibly other functions of the hearing aid that are not further relevant here. Amplification with the aim of compensating for a hearing deficit of the user does not occur in the upper frequency range, but exclusively in the operating range.

[0031] Alternatively or additionally, a speech frequency range is completely or at least predominantly (i.e. in particular at least 90%) covered by the lower frequency range. The speech frequency range specifies in particular precisely the frequency range within which speech lies. The speech frequency range extends, for example, from 100 Hz to 4 kHz, to 6 kHz, to 8 kHz or to 12 kHz; the higher upper limits apply in particular when harmonics are taken into account. The precise definition of the speech frequency range is initially not important, however; what is more important is that speech is predominantly or completely covered by the lower frequency range and accordingly is not present or is only negligibly present in the upper frequency range.

[0032] Conveniently, the speech frequency range is completely encompassed by the operating range. A configuration in which the operating range and the speech frequency range have the same upper and / or lower limit is also possible and suitable. However, configurations in which the operating range is larger or smaller than the speech frequency range are also conceivable. Especially in a configuration in which the operating range also encompasses the upper frequency range, the operating range is then larger than the speech frequency range, which is preferably limited to the lower frequency range or less.

[0033] Suitably, the upper frequency range has an upper limit that corresponds at least to the upper limit of the aforementioned speech frequency range. This ensures that in the upper frequency range, speech is not misdetected as transient and / or impulsive noise.

[0034] In a first variant, the lower frequency range has an upper limit of 12 kHz. This upper limit is also preferably, but not necessarily, a lower limit of the upper frequency range. The upper limit of 12 kHz is based on the consideration that speech then lies entirely in the lower frequency range, thus avoiding false detection of background noise with the detector in the upper frequency range. Furthermore, for the same reason, typical hearing aids usually have an operating range with an upper limit of 12 kHz. The lower frequency range also has a lower limit, the exact value of which is not relevant here. A lower limit of 20 Hz, for example, is suitable.

[0035] The upper frequency range has an upper limit, which is suitably defined by a technical boundary condition of the hearing aid, in particular a limited frequency range of the filter bank and / or a limited sampling rate of an A / D converter (i.e. analog-to-digital converter) which digitizes the input signal from the microphone. Alternatively or additionally, in a second variant the upper frequency range has a lower limit of 12 kHz and an upper limit of 16 kHz. The lower limit results in particular from the same considerations as the upper limit of the lower frequency range. The upper limit of 16 kHz results in particular from usual technical boundary conditions of the hearing aid, in particular a sampling rate of 32 kHz of an A / D converter of the hearing aid.

[0036] In a suitable embodiment, the hearing aid has an A / D converter for digitizing the input signal, and the upper frequency range has an upper limit that corresponds to at most half of the sampling rate of the A / D converter. The upper frequency range is thus determined by a technical boundary condition that is predetermined by the A / D converter. Depending on the design of the hearing aid, a corresponding upper limit then results for the upper frequency range. In a suitable embodiment, the A / D converter has a sampling rate of 32 kHz, so that the upper limit corresponds to a maximum of 16 kHz. The sampling rate is in particular an actually set sampling rate of the A / D converter, i.e. the sampling rate that is actually set. For example, the A / D converter itself has a significantly higher possible sampling rate, e.g., several MHz, but is operated as an oversampling A / D converter (i.e.as an “oversampled A / D converter”) with a significantly lower, actually set sampling rate of 32 kHz. The sampling rate, especially the actually set sampling rate with an oversampling A / D converter, is also regularly subject to a tolerance, which arises in particular from a deviation of the oscillation frequency of a quartz crystal used to clock the A / D converter from an ideal frequency and, on the other hand, from multiple division of the oscillation frequency, in particular by 2, up to the actually set sampling rate. In other words: an actually set sampling rate of 32 kHz actually corresponds to a sampling rate of 32 kHz plus or minus a tolerance of, for example, 5%.

[0037] The method according to the invention serves to operate a hearing aid, in particular a hearing aid as described above. The hearing aid has a microphone, a signal processor and a detector. In the method, i.e. during operation of the hearing aid, sound signals are recorded by means of the microphone within a total frequency range and converted into an input signal. Furthermore, the input signal is processed exclusively or at least within a lower frequency range which is part of the total frequency range by means of signal processing. The detector then detects an interference noise which has frequency components both within the lower frequency range and outside it, namely in an upper frequency range above the lower frequency range, the detector detecting the interference noise on the basis of its frequency component in the upper frequency range.Advantages and preferred refinements are evident from what has already been said. It is advisable to suppress the noise in the input signal and output the input signal via an earpiece.

[0038] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In each case, the following schematically show: Fig. 1 a hearing aid, Fig. 2 a frequency spectrum, Fig. 3 a different frequency spectrum, Fig. 4 a section of the frequency spectrum from Fig. 3.

[0039] In Fig. 1 shows an embodiment of a hearing aid 2 according to the invention. This has at least one microphone 4, which is designed to record sound signals 6 within a total frequency range Fg and to convert them into an input signal 8. The hearing aid 2 also has a signal processing unit 10 for processing the input signal 8 within a lower frequency range Fu, which is a part of the total frequency range Fg. Thus, the hearing aid 2 has an operating range Fa, which at least, and in the embodiment shown here, even exclusively, contains the lower frequency range Fu. The hearing aid 2 also has a detector 12 for detecting an interference noise 14, which has frequency components both within the lower frequency range Fu and outside of it, namely in an upper frequency range Fo above the lower frequency range Fu. This is shown in Fig. 2, which shows, by way of example, a spectrum of the input signal 8, i.e., its amplitude A as a function of the frequency F. For the sake of clarity, the background noise 14 and the wanted noise 16 are shown separately, although it is clear that they are mixed to form the input signal 8, possibly with other wanted noises and / or background noises, which are not explicitly shown for the sake of clarity. Furthermore, the hearing aid 2 is designed such that the detector 12 detects the background noise 14 based on its frequency component in the upper frequency range Fo.

[0040] In the present case, the upper frequency range Fo directly adjoins the lower frequency range Fu, but this is not mandatory. The upper frequency range Fo and the lower frequency range Fu do not overlap in the illustrated embodiment. The upper frequency range Fo is also not part of the operating range Fa, but this is not mandatory in itself, so that a design is also possible in which the operating range Fa also contains the upper frequency range Fo in whole or in part. The upper frequency range Fo is primarily characterized by the fact that fewer useful noises 16 are present and / or to be expected in it than in the lower frequency range Fu, as also shown by way of example in Fig. 2 is recognizable. Outside the lower frequency range Fu, the proportion of speech (which is a useful noise 16) is also regularly particularly low.

[0041] Sound signals 6 in general and background noise 14 in particular are not limited to the operating range Fa of the hearing aid 2, but can also lie outside of it. Transient and / or impulsive background noise 14 in particular are broadband and thus span a wide frequency range, thus also having high-frequency components that regularly lie outside the operating range Fa, as in Fig. 2 for the background noise 14 shown there (the terms “component” and “frequency component” are generally considered equivalent and used interchangeably). The detection of such background noise 14 is particularly unreliable when detection occurs at low frequencies, e.g. in the working range Fa of the hearing aid 2, where other stationary and non-stationary background noises (in Fig. 2 not explicitly shown) are present, which are often also louder, ie have a higher amplitude A. In addition, non-stationary components of speech can also lead to false detections, ie speech which is actually a useful noise 16 is falsely detected as noise 14.

[0042] However, it has been observed that the amplitude A of high-frequency noise 14 is often lower than the amplitude A of low-frequency noise 14, which typically lies within the working range Fa. For example, in a restaurant or canteen, cutlery and dishes, when knocked together, produce a clinking noise 14, which is a quiet, transient and / or impulsive noise 14 and also has a high-frequency component, which regularly lies outside the working range Fa, as exemplified in Fig. 2. Especially such background noises 14 are now better detected by the hearing aid 2, since even quiet background noises 14 are detected in the upper frequency range Fo. The risk of false detections is reduced, since no or only a few useful noises 16 are to be expected in the upper frequency range Fo, since these are predominantly or exclusively in the lower frequency range Fu, as also exemplified in Fig. 2. Thus, quiet, transient, and / or impulsive noises 14 are detected in this case, specifically by monitoring the upper frequency range Fo. A transient and / or impulsive noise 14 is thus detected based on its frequency component outside the lower frequency range Fu. This takes advantage of the fact that the noise 14 is broadband and has frequency components in both the lower and upper frequency ranges Fu, Fo.

[0043] Suppression of the noise 14 is carried out, for example, by means of the signal processing 10 and then, if necessary, only within the lower frequency range Fu and not necessarily in the upper frequency range Fo.

[0044] The hearing aid 2 shown here is used to provide sound to a hearing-impaired user, i.e., a user with a hearing deficit. For this purpose, the hearing aid 2 has the aforementioned microphone 4, which picks up sound signals 6 from the environment and generates the electrical input signal 8. This is fed to the aforementioned signal processing unit 10 for processing (here specifically amplification), which is also part of a control unit 18 of the hearing aid 2. The processing is carried out based on an individual audiogram of the user, which is assigned to the hearing aid 2, so that an individual hearing deficit of the user is compensated. The signal processing unit 10 outputs an electrical output signal 20 as a result, which is then output to the user via a receiver 22 of the hearing aid 2.In an alternative not shown, the hearing aid 2 is merely a headphone and then has, for example, a noise suppression for the targeted suppression of background noise 14, which accordingly benefits from the detection of background noise 14 described here.

[0045] The precise design of detector 12 is not relevant here; what is more important is that it operates in the upper frequency range Fo and searches for an interfering noise 14 there. In principle, a conventional detector 12 is suitable, which would otherwise be used in the lower frequency range Fu, but now monitors the upper frequency range Fo instead. Limiting detector 12 to the upper frequency range Fo results, for example, in detector 12 exclusively monitoring the upper frequency range Fo or in only supplying the upper frequency range Fo to detector 12.

[0046] In the embodiment shown here as an example, the hearing aid 2 has a filter bank 24 which divides the input signal 8 into a plurality of channels, each of which is assigned to a frequency band. The filter bank 24 is designed separately from the signal processing unit 10, but alternatively is integrated into it. The filter bank 24 has a plurality of channels, in particular at least three, but typically a double-digit number. A first subset of the channels then forms the lower frequency range Fu, and a second, different subset of the channels analogously forms the upper frequency range Fo, which is then fed to the detector 12. Independently of this, a filter bank 24 is also advantageous for suppressing the background noise 14, because then the amplification can be specifically adjusted in each individual channel, so that precisely those components which belong to a background noise 14 are specifically reduced.A configuration is also possible in which the filter bank 24 is limited to the lower frequency range Fu and the upper frequency range Fo is guided past the filter bank 24 to the detector 12. This is shown in . Fig. 1, according to which the input signal 8 is fed in its entirety to the detector 12, which then controls the signal processing unit 10 to suppress any noise. Alternatively or additionally, the detector 12—as already indicated—controls the filter bank 24 for suppression. Furthermore, in a variant not shown—as also already indicated—the detector 12 is not fed with the input signal 8 in its entirety, but only with the upper frequency range Fo from the filter bank 24.

[0047] In the present case, the detector 12 is designed, for example, as a level detector and thus detects the interference 14 as such if its amplitude A in the upper frequency range Fo exceeds a minimum amplitude M. If the minimum amplitude M in the upper frequency range Fo is exceeded, the detector 12 triggers and thereby detects an interference 14. The minimum amplitude M is selected to be lower (e.g., half as large) than a minimum amplitude M that would be selected for a detector that monitors the lower frequency range Fu. Such a detector for the lower frequency range Fu is not used here, but is present in an alternative (not shown) in addition to the detector 12 described here for the upper frequency range Fo, e.g., to detect narrowband interference in the lower frequency range Fu, which is not possible with the detector 12 described here.Accordingly, the detector for the lower frequency range Fu then has a higher minimum amplitude M than the detector 12 for the upper frequency range Fo. However, to detect interference noise 14 in the lower frequency range Fu, a minimum amplitude M is required which is greater than the usual or maximum achievable amplitude A of useful noise 16 in the lower frequency range Fu, as can be seen from . Fig. 2 is recognizable. Since there are no or only few useful noises 16 in the upper frequency range Fo, a correspondingly lower minimum amplitude M is possible here and even quiet background noises 14 are recognized.

[0048] Detector 12 is, for example, a gradient-based pulse detector. A design as a gradient detector or wavelet detector is also possible, as is a combination of the designs mentioned here and above.

[0049] As already mentioned, the upper frequency range Fo is not part of the operating range Fa of the hearing aid 2 in the embodiment shown. For this purpose, the lower frequency range Fu is an operating range Fa of the signal processing unit 10, so that the processing of the input signal 8 by the signal processing unit 10 is limited to the lower frequency range Fu. The signal processing unit 10 therefore does not process the upper frequency range Fo; this is only used for the detector 12 and possibly other functions of the hearing aid 2 that are not further relevant here. It is irrelevant whether the filter bank 24 merely passes the lower frequency range Fu to the signal processing unit 10, or whether the signal processing unit 10 rejects the upper frequency range Fu from the signal of the filter bank 24 or simply leaves it unprocessed. Amplification with the aim of compensating for a hearing deficit of the user does not occur in the upper frequency range Fo.

[0050] In Fig. 2 also shows a speech frequency range Fs which, in the present example, is completely encompassed by the lower frequency range Fu. The speech frequency range Fs indicates the frequency range within which speech lies. In the present case, the speech frequency range Fs extends from 100 Hz to 4 kHz or to 12 kHz if overtones are taken into account. In the present case, the speech frequency range Fs is completely encompassed by the working range Fa. However, an alternative embodiment (not shown) is also possible in which the working range Fa and the speech frequency range Fs have the same upper limit and / or lower limit. Embodiments are also conceivable in which the working range Fa is larger or smaller than the speech frequency range Fs. In particular, in an embodiment in which the working range Fa also includes the upper frequency range Fo, the working range Fa is then larger than the speech frequency range Fs.

[0051] For example, the lower frequency range Fu has an upper limit 26 of 12 kHz. This upper limit 26 is also, but not necessarily, a lower limit 28 of the upper frequency range Fo.

[0052] The upper frequency range Fo has an upper limit 30, which in this case is defined by a technical boundary condition of the hearing aid 2, e.g., a limited frequency range of the filter bank 24 and / or a limited sampling rate of an A / D converter 32 (i.e., analog-to-digital converter) which digitizes the input signal 8 from the microphone 4. In the embodiment shown here, the upper frequency range Fo has a lower limit 28 of 12 kHz and an upper limit 30 of 16 kHz. The lower limit 28 results from the same considerations as the upper limit 26 of the lower frequency range Fu. The upper limit 30 of 16 kHz results here from the technical boundary condition of a sampling rate of 32 kHz of the A / D converter 32.

[0053] For further illustration, Fig. 3 shows a frequency spectrum in an exemplary environment, here a cafeteria. The frequency F is plotted vertically and the time T horizontally. The amplitude A for a given frequency F at a given time T is shown in grayscale, where: the brighter / whiter, the greater the amplitude A, and vice versa, the darker / blacker, the lower the amplitude A. Fig. 3, the upper frequency range Fo is framed for identification, and the lower frequency range Fu is located immediately below the upper frequency range Fo. The frame contains the frequency range from 11 kHz to 16 kHz. Fig. 4, this frequency range is within the frame of Fig.3 is shown enlarged, making the structure of the upper frequency range Fo more clearly visible. Numerous bright, vertical stripes are clearly visible, i.e., high amplitudes A for only short periods T, which result from impulsive and / or disturbing noises 14. List of reference symbols 2 hearing aids 4 Microphone 6 Sound signal 8 Input signal 10 Signal processing 12 detector 14 Noise 16 Useful noise 18 Control unit 20 Output signal 22 listeners 24 filter bank 26 Upper limit (of the lower frequency range) 28 Lower limit (of the upper frequency range) 30 Upper limit (of the upper frequency range) 32 A / D converters A Amplitude F Frequency Fa work area Fg total frequency range Fo upper frequency range Fs speech frequency range Fu lower frequency range M Minimum amplitude T Time

Claims

[1] Hearing aid (2), - which has at least one microphone (4) which is designed to record sound signals (6) within a total frequency range (Fg) and to convert them into an input signal (8), - which has a signal processing unit (10) for processing the input signal (8) within a lower frequency range (Fu), which is part of the total frequency range (Fg), - which has a detector (12) for detecting an interference noise (14) which has frequency components both within the lower frequency range (Fu) and outside it, namely in an upper frequency range (Fo) above the lower frequency range (Fu), - which is designed such that the detector (12) detects the interference noise (14) on the basis of its frequency component in the upper frequency range (Fo), wherein the lower frequency range (Fu) has an upper limit (26) of 12 kHz and / or wherein the upper frequency range (Fo) has a lower limit (28) of 12 kHz and an upper limit (30) of 16 kHz. [2] Hearing aid (2) according to claim 1, wherein the detector (12) is a pulse detector. [3] Hearing aid (2) according to claim 1 or 2, wherein the detector (12) is designed as a level detector and thereby detects the noise (14) as such if its amplitude (A) in the upper frequency range (Fo) exceeds a minimum amplitude (M). [4] Hearing aid (2) according to one of claims 1 to 3, wherein the detector (12) is designed as a gradient detector and thereby detects the disturbing noise (14) as such if its amplitude (A) in the upper frequency range (Fo) undergoes a minimum change during a predefined time interval. [5] Hearing aid (2) according to one of claims 1 to 4, wherein the detector (12) is designed as a wavelet detector and thereby detects the noise (14) as such on the basis of its spectral shape. [6] Hearing aid (2) according to one of claims 1 to 5, wherein the noise (14) is a transient and / or impulsive noise (14). [7] Hearing aid (2) according to one of claims 1 to 6, wherein the disturbing noise (14) is generated by clinking dishes and / or cutlery. [8] Hearing aid (2) according to one of claims 1 to 7, wherein the lower frequency range (Fu) is a working range (Fa) of the signal processing (10), so that the processing of the input signal (8) by the signal processing (10) is limited to the lower frequency range (Fu). [9] Hearing aid (2) according to one of claims 1 to 8, wherein a speech frequency range (Fs) is completely or at least predominantly covered by the lower frequency range (Fu). [10] Hearing aid (2) according to one of claims 1 to 9, wherein the upper frequency range (Fo) has an upper limit (30) which corresponds at least to an upper limit of a speech frequency range (Fs). [11] Hearing aid (2) according to one of claims 1 to 10, wherein it comprises an A / D converter (32) for digitizing the input signal (8), wherein the upper frequency range (Fo) has an upper limit (30) which corresponds at most to half a sampling rate of the A / D converter (32). [12] Method for operating a hearing aid (2) which has at least one microphone (4), a signal processing unit (10) and a detector (12), - wherein sound signals (6) are recorded by means of the microphone (4) within a total frequency range (Fg) and converted into an input signal (8), - wherein the input signal (8) is processed by means of the signal processing (10) within a lower frequency range (Fu), which is part of the total frequency range (Fg), - wherein an interference noise (14) is detected by means of the detector (12) which has frequency components both within the lower frequency range (Fu) and outside it, namely in an upper frequency range (Fo) above the lower frequency range (Fu), - wherein the detector (12) detects the noise (14) based on its frequency component in the upper frequency range (Fo), - wherein the lower frequency range (Fu) has an upper limit (26) of 12 kHz and / or wherein the upper frequency range (Fo) has a lower limit (28) of 12 kHz and an upper limit (30) of 16 kHz.

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