Hearing device and method for signal processing in a hearing device

Abstract

A hearing device (2) has an input converter (4), a signal processing unit (6) and an output converter (8), the signal processing unit (6) having a filter bank (14) for dividing an input signal (E, E ') into a plurality of signal portions (Sf) in different frequency bands, a processing unit (12) for processing the signal portions (Sf), and a processing unit (14) for synthesizing the processed signal portions (Sf) into output signals (A, B). A ') of the unit (18). In order to limit one of the levels of the output signal (A), a level detector (20) is arranged before the synthesis unit (18), said level detector being designed to determine the signal level (P) on the basis of the signal portion (Sf) and to output a level signal (Sp). The level signal (Sp) is transmitted to a level limiter (24), which is arranged after the synthesis unit (18) and is designed to limit the level of the output signal (A) as a function of the level signal (Sp).

Description

Field of the Invention

[0001] The present invention relates to a hearing device having an input transducer, a signal processing unit, and an output transducer, wherein the signal processing unit has a filter bank for dividing an input signal into signal portions in a plurality of different frequency bands, a processing unit for processing the signal portions, and a synthesis unit for synthesizing the processed signal portions into an output signal. The present invention also relates to a method for signal processing. Background Art

[0002] Such a hearing device and method are known from patent document EP 2 389 773 B1. The problem addressed by this prior art and even by the present invention is that, at high input signal levels, i.e., when the sound source is louder, signal processing in the hearing device results in an overly high signal level at the end of signal processing, such that the signal output to the user is perceived as uncomfortable by the user. In addition, when the electrical signal is converted into an acoustic signal for the user, the high signal level also results in a high energy requirement and high current peaks. This in turn leads to a weakening of the energy supply and, for example, voltage drops, which can cause malfunctions of the hearing device.

[0003] According to patent document EP 2 389 773 B1, the signal level of the electrical input signal is determined before the input signal is fed to the filter bank and divided therein into different signal portions in different frequency bands (frequency channels). In particular, the instantaneous strong noise in the input signal, i.e., the so-called transients, is determined. Depending on whether a transient is recognized, the calculation of the amplification factor is performed and, if necessary, adjusted in a single frequency band (frequency channel). Then, the different signal portions of the different channels are combined in an adder and provided as an electrical output signal, which is then converted into an acoustic output signal in the output transducer. Summary of the Invention

[0004] Starting therefrom, the technical problem to be solved by the present invention is to provide better signal limitation when the input signal is strong, especially when the above-mentioned transients are present.

[0005] The above technical problem is solved according to the invention by means of a hearing device having an input transducer, a signal processing unit and an output transducer, wherein the signal processing unit has a filter bank for dividing an input signal into different frequency bands and thus into a plurality of signal portions in different channels, a processing unit for processing the signal portions and a synthesis unit for synthesizing the processed signal portions into an output signal. The output signal is then transmitted at least indirectly to the output transducer. The signal processing unit also has a level detector which is designed to determine a signal level based on the signal portions and to output a level signal. The level detector is arranged in front of the synthesis unit here. Furthermore, a level limiter is provided, to which the level signal is transmitted and which is designed to limit the level of the output signal as a function of the level signal.

[0006] The invention also solves the problem by means of a method for signal processing, in particular in such a hearing device, wherein

[0007] - the input signal is divided into a plurality of signal portions in different frequency bands,

[0008] - the signal portions are processed,

[0009] - the processed signal portions are combined into an output signal,

[0010] - a signal level is determined based on the signal portions and a level signal is generated on this basis,

[0011] - the level of the output signal is limited based on the level signal.

[0012] It should be emphasized that the signal level is determined based on the signal portions and thus only after the filter bank. By this measure, the signal level can be determined and it can thus be determined whether signal limitation is required only when at least some steps in the signal processing have been carried out, so that it is possible to determine more precisely and to estimate whether there is an excessive level in the output signal.

[0013] It should also be emphasized that the level limiter is arranged behind the synthesis unit and acts on the output signal composed of the processed signal portions. The signal limitation is thus carried out in a broadband manner, such that the signal limitation acts on the combined, composed output signal and not just on individual frequency bands. This avoids signal distortion due to different frequency-specific and thus channel-specific amplification factors.

[0014] The level limiter is generally arranged behind the level detector with respect to the signal processing path and is thus temporally offset with respect to the level detector in signal processing. Given that a certain processing time is required for level detection, level limiting is thus ensured in a timely manner. The inherent delay in the (further) signal processing between the level detector and the level limiter is thus utilized in a suitable manner in order to reliably perform level limiting in the presence of high levels. Overall, this decouples level determination and level limiting in time.

[0015] The signal processing unit is in particular a digital signal processing unit, which is specifically designed as a digital signal processor. Here, a filter bank is generally understood as a processing unit that divides an electrical input signal supplied to the signal processing unit into a plurality of frequency bands and into a plurality of frequency channels, where, before the different signal parts are combined again, one signal part is analyzed and processed in each channel.

[0016] The processing unit for processing the signal parts thus has a channel-specific processing unit for each frequency band and thus for each frequency channel. Each of these channel-specific processing units generally has a plurality of channel-specific signal processing components here, such as channel-specific filters or even channel-specific amplifier components.

[0017] The conversion of the input signal from the time domain to the frequency domain is generally carried out by means of a filter bank. The signal processing within the processing unit and thus the processing of the signal parts is therefore carried out in the frequency domain.

[0018] Generally, the (electrical) input signal is first provided to the signal processing unit in the time domain, whereupon the signal is then converted to the frequency domain by the filter bank. Finally, the conversion from the frequency domain to the time domain is carried out again by the synthesis unit. The output signal is thus provided in the time domain after the synthesis unit.

[0019] By arranging the level detector in front of the synthesis unit and the level limiter behind the synthesis unit, it is utilized that a certain processing time (delay) is required for the conversion from the frequency domain to the time domain, which is used for level determination and in particular for reliably performing level limiting at the desired time point.

[0020] In a preferred design, the level detector is arranged behind at least one signal processing component of the processing unit. This ensures that at least one and preferably a plurality of signal processing steps have been carried out within the processing unit and thus in particular within the processing in the frequency domain before level determination is carried out.

[0021] In a preferred design, one of these signal processing components is a (channel-specific) amplifier component, and level determination is carried out only after such a channel-specific amplifier component.

[0022] Overall, this ensures that the signal level is determined based on the already processed signal portion, so that the estimation and determination of whether an excessive level is expected in the output signal can be carried out as reliably as possible.

[0023] Preferably, the level detector is arranged directly before the synthesis unit. The level detector is arranged here after the complete signal processing of the signal portion. Thus, the level detector is arranged after the last signal processing component of the processing unit.

[0024] In a preferred design, the level limiter is arranged after the output processing unit, which is designed to process the output signal output by the synthesis unit. This output processing unit is typically a signal processing unit located after the synthesis unit, which thus particularly performs signal processing on the already synthesized electrical output signal. In the scope of this output signal processing unit, for example, signal filtering and / or scaling are carried out in the time domain.

[0025] In a preferred refinement, the level detector and the level limiter are directly connected to each other, such that in operation the level signal is transmitted directly from the level detector to the level limiter. Being directly connected to each other or directly transmitted here is understood to mean that no additional processing unit for signal processing is provided on the signal path for the level signal, and in particular there is no signal delay through the direct and straight connection. The level detector is thus directly connected to the level limiter by a direct, simple signal line, such as a conductor circuit. This enables the fastest possible signal transmission to the level limiter.

[0026] Furthermore, in a preferred refinement, the input signal processing unit is arranged before the filter bank, which is designed to process the input signal before the filter bank. Here, in particular, the first signal processing is still carried out in the time domain before the division into different frequency bands. In the scope of this input signal processing unit, for example, filtering and / or scaling are carried out in the time domain.

[0027] Therefore, preferably, supplementary signal processing steps for the corresponding total signal in the time domain are carried out on the input side and the output side of the processing unit and thus before and after the signal processing in the frequency domain.

[0028] Preferably, the level detector and the level limiter are designed such that the level signal is related to the signal level, and in particular, after exceeding the limit value for the signal level, as the signal level increases, the limitation of the level of the output signal increases. Thus, in this case, the level signal also contains information about the magnitude of the signal level determined by the level detector. In particular, continuous adjustment of the limitation is provided, or alternatively, adjustment of the limitation in discrete steps is also provided.

[0029] According to an alternative variant thereof, for example, from the moment the limit value for the signal level is exceeded, a fixed, predetermined limitation, in particular a fixed limitation factor, is set.

[0030] Determining signal levels based on channel-specific signal components in the frequency domain is generally known. Individual signal components in different channels are typically analyzed and evaluated for this purpose. In particular, for example, the channel-specific signal levels are determined individually and checked for violations of channel-specific limit values. The level detector may include, for example, a channel-specific level detector for each channel.

[0031] For example, if a channel-specific limit value is exceeded in a channel, a level signal is output for limiting the level of the output signal.

[0032] In a preferred embodiment, the level detector is designed to estimate the broadband signal level based on the signal components. This is understood to mean that a common, expected signal level is determined based on a plurality of, and in particular all, signal components, which is present in the combined output signal after the combining unit and before the level limiter, in particular before the output signal processing unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The embodiments of the present invention are further described below with reference to the single figure.

[0034] Figure 1 Signal processing in a hearing instrument is illustrated by way of example using a simplified block diagram. DETAILED DESCRIPTION

[0035] Figure 1 The hearing device 2 shown in FIG. 1 is designed, in particular, as a hearing aid device that is designed and configured to compensate for a user-specific hearing impairment. This hearing device 2 is adapted to the user-specific hearing impairment of a determined user through a fitting process, for example, at the hands of an audiology acoustician. To this end, the values of various setting parameters are appropriately adjusted.

[0036] The hearing instrument 2 typically comprises an input converter 4, a digital signal processing unit 6, and an output converter 8. Typically, an electrical digital input signal E is provided via the input converter 4 at the input of the signal processing unit 6. This digital input signal E is processed by the signal processing unit 6 and provided as a digital output signal A at the output of the signal processing unit 6 and transmitted to the output converter 8.

[0037] The input converter 4 and / or the output converter 8 are usually, but not necessarily, electroacoustic converters, which convert acoustic signals into electrical signals and vice versa. In particular, the input converter 4 is a microphone and the output converter 8 is an earpiece / loudspeaker.

[0038] In the embodiment shown, the input signal E is first subjected to a first signal processing in the input processing unit 10. This first signal processing is performed in the time domain.

[0039] Subsequently, a processing unit 12 is arranged, where signal processing in the frequency domain is performed. For this purpose, the processing unit 12 has a filter bank 14 on the input side, which divides the input signal E, in particular the processed input signal E' provided by the input processing unit 10, into a plurality of signal parts Sf in different frequency bands or frequency channels. The corresponding frequency channels are represented by corresponding lines within the processing unit 12. Thus, within the processing unit 12, frequency-specific or channel-specific processing of the input signals E, E' is performed in the frequency domain. Figure 1 are represented by corresponding lines within the processing unit 12. Thus, within the processing unit 12, frequency-specific or channel-specific processing of the input signals E, E' is performed in the frequency domain.

[0040] The processing unit 12 itself also has a plurality of signal processing components 16, which apply various signal processing functions to the signals. In particular, one of these signal processing components 16 is designed as an amplifier component. The corresponding signal processing components 16 are typically divided into channel-specific signal processing components that are preferably identical to each other.

[0041] A synthesis unit 18 is arranged after the processing unit 12, where the different signal parts Sf are combined again into a common output signal A, A'. The output signal output by the synthesis unit is provided with the reference sign A' here.

[0042] The processing unit 12 also has a level detector 20, which is designed to determine the signal level P, in particular of a broadband signal. Based on the signal level P determined by the level detector 20, it outputs a level signal Sp.

[0043] In the embodiment, the output signal A' output by the synthesis unit 18 is transmitted to an output processing unit 22, where further signal processing is now performed again in the time domain.

[0044] Figure 1 show three dashed regions I, II, III within the signal processing unit, where the input-side region I and the output-side region III mark signal processing in the time domain, and the region II arranged therebetween marks signal processing in the frequency domain.

[0045] A level limiter 24 is arranged after the output processing unit 22. It is in particular part of a final amplifier not shown in detail here. The level signal Sp is directly transmitted from the level detector 20 to the level limiter 24. The level of the output signal A provided at the output of the signal processing unit 6 and transmitted to the output converter 8 is limited by the level limiter 24 if necessary.

[0046] The output signal A is then preferably converted by the output converter 8, in particular a loudspeaker, into an acoustic output signal and presented to the user.

[0047] The level detector 20 determines the broadband signal level P based on a plurality of signal portions Sf, in particular based on all signal portions Sf. This is generally a measure of the expected signal level in the output signal A' output by the processing unit 12 at its output.

[0048] To determine the signal level P, in particular the channel-specific signal levels of the individual signal portions SF are determined and combined into the signal level P.

[0049] The broadband signal level in the frequency domain is in particular generated by adding up the linear signal powers (partial powers) of all frequency bands (the square of the absolute value of the signal portion Sf). Here, preferably, a correction factor is applied to each partial power in the case where the band overlap between sub-bands at the output of the filter bank is preferably constant. After the addition, the broadband level is determined, for example, by taking the logarithm of the linear total signal line. This method is also known in the specialist literature as the "modified periodogram".

[0050] If the signal level P determined in this way is higher than a predetermined, possibly user-specific limit value, the level signal Sp is output to the level limiter 24 as an indication of exceeding the limit value.

[0051] In particular, the level signal Sp is related to the determined signal level P and thus contains information about the actual magnitude of the determined signal P. The limitation carried out by the level limiter 24 when the limit value is exceeded is related to the signal level P, that is, as the signal level P increases, the limitation increases in particular continuously.

[0052] Overall, this enables appropriate, reliable and rapid limitation of the level of the output signal A in the case of transient or generally higher input levels.

[0053] List of reference signs

[0054] 2 Hearing device

[0055] 4 Input transducer

[0056] 6 Signal processing unit

[0057] 8 Output transducer

[0058] 10 Input processing unit

[0059] 12 Processing unit

[0060] 14 Filter bank

[0061] 16 Signal processing component

[0062] 18 Synthesis unit

[0063] 20 Level detector

[0064] 22 Output processing unit

[0065] 24 Level limiter

[0066] E Input signal

[0067] E' Input signal at the input terminal of processing unit 12

[0068] A Output signal

[0069] A' Output signal at the output terminal of processing unit 12

[0070] Sf Signal part

[0071] Sp Level signal

[0072] Signal processing in time domains I, III

[0073] Signal processing in frequency domain II

Claims

1. A hearing device (2) having an input transducer (4), a signal processing unit (6) and an output transducer (8), wherein, The signal processing unit (6) has a filter bank (14) for dividing the input signals (E, E') into a plurality of signal parts (Sf) in different frequency bands, a processing unit (12) for processing the signal parts (Sf), and a synthesis unit (18) for synthesizing the processed signal parts (Sf) into output signals (A, A'). It is characterized in that a level detector (20) is arranged in front of the synthesis unit (18), the level detector is designed to determine a signal level (P) based on the signal parts (Sf) and to output a level signal (Sp), and a level limiter (24) is also arranged after the synthesis unit (18), the level signal (Sp) is sent to the level limiter, and the level limiter is designed to limit the level of the output signal (A) according to the level signal (Sp).

2. The hearing device (2) according to the above-mentioned claim, characterized in that, The level detector (20) is arranged after at least one signal processing component (16) of the processing unit (12).

3. The hearing device (2) according to the above-mentioned claims, characterized in that, The level detector (20) is arranged directly in front of the synthesis unit (18).

4. The hearing device (2) according to one of the preceding claims, characterized in that, The level limiter (24) is arranged after an output processing unit (22), and the output processing unit is designed to process the output signal (A') provided by the synthesis unit (18).

5. The hearing device (2) according to one of the preceding claims, characterized in that, The level detector (20) and the level limiter (24) are directly connected to each other to directly transmit the level signal (Sp).

6. The hearing device (2) according to one of the preceding claims, characterized in that, An input processing unit (10) is arranged in front of the filter bank (14), and the input processing unit is designed to process the input signal (E) in front of the filter bank (14).

7. The hearing device (2) according to one of the preceding claims, characterized in that, The level detector (20) and the level limiter (24) are designed such that the level signal (Sp) is associated with the signal level (P), and as the signal level (P) increases, the limitation of the level of the output signal (A) increases.

8. The hearing device (2) according to one of the preceding claims, characterized in that, The level detector (20) is designed to estimate a broadband signal level (P) based on the signal parts (Sf).

9. A method for signal processing in a hearing device (2) according to in particular one of the preceding claims, wherein - the input signals (E, E') are divided into a plurality of signal parts (Sf) in different frequency bands, - the signal parts (Sf) are processed, - the processed signal parts (Sf) are combined into output signals (A, A'), characterized in that - a signal level (P) is determined based on the signal parts (Sf) and a level signal (Sp) is generated based thereon, - the level of the output signal (A) is limited based on the level signal (Sp).

10. The method according to the above-mentioned claims, wherein, The determination of the signal level (P) is carried out directly before the combination of the signal parts (Sf).

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