METHOD FOR DIRECTION-DEPARATE NOISE REDUCTION FOR A HEARING SYSTEM COMPLETING A HEARING DEVICE

Description

[0001] The invention relates to a method for direction-dependent noise suppression for a hearing system, which comprises a hearing device, wherein, by means of at least one first input transducer of the hearing system and a second input transducer of the hearing system, an interference signal and a target signal are generated from ambient sound, wherein the interference signal and / or the target signal are referenced to a first useful signal source arranged in a first direction, wherein, for at least a plurality of frequency bands, a weighting factor for the respective frequency band is determined on the basis of an acoustic characteristic of the target signal and a corresponding acoustic characteristic of the interference signal, and wherein an input signal of the hearing system to be processed is weighted frequency-band by frequency on the basis of the respective weighting factor, and an output signal is generated on the basis of the input signal weighted in this way.

[0002] Hearing aids are portable devices used to compensate for a wearer's hearing loss. They typically begin by amplifying the level of specific frequencies, usually tailored to the individual wearer, to make sound audible in those frequency bands that would otherwise be inaudible or too quiet without the aid. To further support the wearer, hearing aids often amplify a target signal (usually speech) relative to ambient noise. This increase in the signal-to-noise ratio (SNR) is primarily achieved through two separate mechanisms.

[0003] The first approach uses two or more microphones, which, through directional microphone techniques, allow for direction-dependent amplification of a target signal while attenuating sound from other directions. While this often achieves satisfactory noise reduction, the spatial perception of the wearer's surroundings is frequently impaired by the suppression of sound from specific directions.

[0004] The second type of noise reduction in hearing aids attempts to filter the energy of interfering signals from the overall signal. This is often achieved through spectral subtraction, for example, using a Wiener filter. The spectrum of interfering signals is estimated (e.g., from pauses in speech) and then subtracted from the overall signal. While spectral subtraction delivers very good results for stationary or slowly changing noise, it is inadequate for rapid spectral changes in the interfering signal or in so-called "cocktail party" situations. Furthermore, spectral subtraction can frequently introduce artifacts that may degrade the speech signal.

[0005] The problem described also applies in a broader sense to other hearing devices in which an input signal is processed and delivered to the ear of a wearer, e.g. headphones, headsets for communication, etc.

[0006] DE 10 2016 225 204 A1 describes a method for operating a hearing aid, comprising at least a first input transducer and a second input transducer, wherein the first input transducer generates a first input signal from an ambient sound signal and the second input transducer generates a second input signal from the sound signal, wherein a first direction is assigned to a first signal source, wherein a first directional signal oriented in the first direction (26) is formed on the basis of the first input signal and the second input signal, and wherein at least signal components of the first directional signal are examined for the presence of a useful signal from a useful signal source of a specified type.

[0007] Publication EP 2 658 289 A1 discloses a method for controlling the directional characteristic of a binaural hearing system, in which a first characteristic value relating to speech in a first direction from a microphone device and a second characteristic value relating to speech in a second direction from the microphone device are determined. A control value is obtained from the difference between the two characteristic values. This control value is used to control the directional characteristic of the microphone device.

[0008] The invention is therefore based on the objective of providing a method for direction-dependent noise suppression for a hearing system with a hearing device, which should allow for the most efficient yet natural-sounding noise suppression possible.

[0009] The aforementioned problem is solved according to the invention by a method for direction-dependent noise suppression for a hearing system, which comprises a hearing device, in particular a hearing aid, wherein, by means of at least a first input transducer of the hearing system and a second input transducer of the hearing system, an interference signal and a target signal are generated from ambient sound, wherein the interference signal and / or the target signal are referenced to a useful signal source arranged in a target direction, wherein the target signal is generated with a target directional characteristic which is homogeneous over a half-space opposite the target direction, wherein, for at least a first plurality of frequency bands, an acoustic characteristic of the target signal is compared with a corresponding acoustic characteristic of the interference signal.wherein preferably a signal level and / or a signal amplitude and / or a signal power of the respective signal is used for the acoustic parameter, and a preliminary weighting factor is determined on the basis of said comparison, the range of values ​​of which has at least three values, wherein a weighting factor for the respective frequency band is formed on the basis of the preliminary weighting factor, and wherein an input signal to be processed of the hearing system is weighted frequency-band by frequency band on the basis of the respective weighting factor, and an output signal is generated on the basis of the input signal to be processed in this way, and wherein a signal with an essentially omnidirectional directional characteristic is generated as the target signal, and a directional signal with a relative attenuation in the target direction is used as the interference signal.

[0010] Alternatively, a directional signal oriented in the target direction is used, which has a lobe-shaped directional characteristic and exhibits an attenuation of at least -10dB in the half-space opposite the target direction, and a cardioid-shaped directional signal with attenuation in the target direction or an omnidirectional signal is used as the interference signal.

[0011] Advantageous and inventive embodiments are the subject of the dependent claims and the following description.

[0012] A hearing device includes, in particular, a hearing aid that is preferably designed and configured to compensate for hearing loss and / or hearing impairment of its wearer. It also includes any device by which a sound signal is converted into a corresponding input signal via an input transducer and processed for reproduction to the wearer's ear, such as headphones or a headset for communication. In the following, an input transducer generally includes any form of electro-acoustic transducer configured to convert ambient sound into a corresponding electrical signal, the voltage or current amplitudes of which preferably reflect the amplitude profile of the ambient sound.In this context, a hearing system is understood to mean, in particular, any system comprising the hearing device and, where applicable, one or more additional devices, and including the required number of input transducers and a control or computer unit for processing the corresponding signals. If the hearing system is not solely comprised of the hearing device, a data connection, in particular a wireless connection, must be established between the aforementioned additional device(s) for transmitting the signals used and / or, where applicable, further information to the hearing device. However, the hearing system can also consist entirely of the hearing device.

[0013] The generation of an interference signal and a target signal using at least one first input transducer and one second input transducer of the hearing system includes, in particular, that the interference signal and / or the target signal is each generated as a directional signal, which is generated using the two signals of the first and the second input transducers. However, this also includes the possibility that the interference signal is generated solely using the first input transducer and the target signal solely using the second input transducer, whereby a reverse assignment to the respective input transducers is also possible. The interference signal and / or the target signal are referenced to a useful signal source, which means, in particular, that the target signal contains a higher proportion of signals from the useful signal source than the interference signal.This can be achieved in particular by attenuating the interference signal in the target direction, but also by relatively emphasizing the target direction compared to other directions or angular ranges in the target signal, or by both of the aforementioned measures.

[0014] Generating the target signal with a target directional characteristic that is homogeneous or substantially homogeneous over a half-space opposite the target direction preferably includes the fact that the target directional characteristic results from signal processing of the input converter(s) used, and that this signal processing is specifically referenced to a free field. The described profile of the target directional characteristic over the aforementioned half-space particularly includes the fact that the sensitivity profile according to the target directional characteristic has no inflection points or local minima, and / or that the sensitivity in the aforementioned half-space exhibits only variations that are suppressed by at least 10 dB, preferably 15 dB, compared to the maximum sensitivity of the target signal (preferably in the target direction).The difference between maximum and minimum sensitivity in the aforementioned half-space is at most -10 dB, preferably at most -15 dB, relative to the maximum sensitivity of the target signal (in the target direction). Such variations can then be neglected compared to a signal contribution from the target direction.

[0015] A homogeneous profile here means, in particular, that within the specified half-space, there is no variation in sensitivity, within the limits of technical feasibility and accuracy. If the angle 0° is assigned to the target direction, the opposite half-space is defined by the angular range from 90° to 270°. Specifically, the profile of the target direction characteristic is homogeneous or substantially homogeneous for the largest possible angular range, with the exception of a range of, for example, + / - 45° around the target direction, and the transition to this range around the target direction is preferably continuous.

[0016] A homogeneous target directional characteristic is achieved in particular by using an omnidirectional target signal. In this case, the signal processing for generating the target signal from the signals of the first and second input converters includes appropriate directional microphones; for generation from only one signal of the two input converters, this can mean, in particular, that the signal processing does not impose any directional characteristics on the target signal.

[0017] For an input signal to be processed, which is generated either by the aforementioned first input converter and / or the aforementioned second input converter, or by a further input converter of the hearing system, frequency-band weighting factors for noise reduction are determined. These factors allow frequency bands with a high noise content in the input signal to be attenuated, and frequency bands with a high content of the desired signal from the source to be relatively boosted. The input signal to be processed is preferably provided by the signal of a single input converter, i.e., the first, the second, or, if applicable, the aforementioned further input converter. Preprocessing, such as A / D conversion, and possibly also pre-amplification, is preferably handled as part of the input converter.

[0018] To determine the weighting factors in individual frequency bands, an acoustic characteristic of the target signal is now calculated for a plurality of frequency bands and compared with the corresponding acoustic characteristic of the interference signal.

[0019] The acoustic parameter is preferably such that it provides information about the energy content of the respective signal in the relevant frequency band. Particularly preferably, the acoustic parameter used is a signal level and / or a signal amplitude and / or a signal power of the respective signal, wherein the aforementioned parameter can either be directly derived from one of the aforementioned signal quantities, or from a monotonic, in particular strictly monotonic, function, e.g., a quadratic or logarithmic function of the signal level and / or the signal power and / or the signal amplitude. For a frequency band, for example, a quotient is formed from the signal level of the target signal in the frequency band as the numerator and the signal level of the interfering signal in the frequency band as the denominator, or the aforementioned signal levels are compared with each other in some other way.

[0020] The comparison of the aforementioned acoustic parameters is then mapped to the preliminary weighting factor, the range of which comprises at least three values, whereby the range of values ​​can be discrete or continuous.

[0021] The comparison can be carried out, in particular, by dividing the aforementioned parameters. Preferably, for at least some frequency bands of the first plurality, a quotient is calculated using the acoustic parameter of the target signal as the numerator and the corresponding acoustic parameter of the interference signal as the denominator, and the preliminary weighting factor is calculated based on the respective quotient. The preliminary weighting factor can be continuous or discrete. In the latter case, the quotient for the relevant frequency bands is specifically mapped monotonically to a range of at least three discrete values ​​to form the preliminary weighting factor, for example, by assigning individual intervals of the quotient's range to individual discrete values ​​of the preliminary weighting factor.

[0022] However, the comparison can also be carried out in such a way that, for at least some frequency bands of the first plurality, the acoustic characteristic of the target signal and the corresponding acoustic characteristic of the interference signal are subjected to a plurality of size comparisons, wherein one of the two characteristics is scaled differently for each size comparison, and wherein, based on the size comparisons, the respective value from the discrete, at least three-valued range is assigned to the preliminary weighting factor.

[0023] For example, for each frequency band, the signal level of the desired signal is compared to the signal level of the interference signal in that band. If the signal level of the desired signal is higher, the highest value from the discrete range for the preliminary weighting factor (e.g., 1.3) is assigned to the frequency band. However, if the signal level of the interference signal is higher, the desired signal can be multiplied by a predefined factor greater than 1, and the next comparison with the interference signal level is performed. If the signal level is now higher, the next value from the discrete range (e.g., 0.75) can be assigned to the preliminary weighting factor for that frequency band. If the interference signal level is still higher, either the lowest value (e.g., 0.5) can be assigned to the preliminary weighting factor, or the process of scaling the desired signal can be repeated.

[0024] Based on the weighting factor determined as described for the respective frequency band, the input signal to be processed can now be weighted accordingly. This can be done either by directly applying the weighting factor to the signal components of the input signal to be processed in the relevant frequency band, or by averaging and / or normalizing the weighting factor over time before multiplying it by the signal components of the corresponding frequency band. Additionally, individual static correction factors can be applied for each frequency band. These factors take into account, for example, spectral differences of the input converters involved for different frequency bands, but also, if applicable, level and / or propagation delay differences, and correct for their corresponding impact on noise reduction.

[0025] An output signal is then generated from the weighted input signal to be processed. This can be achieved, on the one hand, by directly generating the output signal from the signal components of the aforementioned weighted input signal. If necessary, further signal processing of these signal components can take place, such as suppressing acoustic feedback or similar effects, or applying additional frequency-dependent attenuation or boosting depending on the individual audiological requirements of the hearing aid user. Alternatively, the output signal can also be generated using signal components from another source, for example, through directional microphones using a separate signal, or by mixing the weighted input signal with an omnidirectional or directional signal, particularly in a broadband manner.

[0026] The invention is based on the assumption that a useful signal from the useful signal source and a noise signal from one or more noise sources possess different spectral information at any given time, i.e., that the amplitude spectrum and the phase of the sound from the different sources are different at any given time. Since the sound pressure fields of multiple sources add up by superposition, the spectral information is also a sum of the individual components of the individual sources. This means, in particular, that the sound pressure at the location of an input transducer at any given time is a sum of individual sources and reflections, which may be further filtered by transfer functions that take into account the propagation of sound from a source to the respective input transducer.It follows that subtracting the individual spectral components, if known, can lead to selective attenuation or removal of these components from the total sum of the target signal (e.g., at the location of an input converter for the input signal to be processed), or that desired signal components can be selectively chosen and boosted.

[0027] To implement this, the frequency-bandwise energy components of the useful signal and the noise signal are used, ideally at every point in time or at a sufficiently dense sequence of discrete points in time, the latter given, for example, by the sampling rate or by the individual "frames" of a spectral analysis using FFTetc. To determine which energy components originate from the useful signal source or the noise sources at any given time, a direction-dependent filtering of the sound field is performed using the target signal and the interference signal in such a way that the proportion of the useful signal from the useful signal source in the generated target signal is significantly higher than in the generated interference signal, which accordingly contains a significantly higher proportion of noise in its total energy.

[0028] The assumption is now used that in those frequency bands where the acoustic characteristic, which provides information about the respective energy content in the frequency band, is greater for the target signal than for the interference signal, a higher spectral component of the useful signal is present. According to the comparison made as described, the input signal to be processed can be relatively boosted in such a frequency band compared to other frequency bands where the acoustic characteristic of the interference signal is greater than the acoustic characteristic of the target signal, since a higher noise component and a lower useful signal component are assumed in those frequency bands.

[0029] This approach primarily utilizes the spatial isolation that separates the target signal from the interfering signal with respect to sound from the desired signal source. Furthermore, the essentially homogeneous propagation of the target signal in the half-space opposite to the target direction allows for a particularly natural sound image to be achieved.

[0030] To comprehensively account for the spectral components of noise from sources outside the target direction, a noise signal is preferably used that, within the aforementioned half-space, also exhibits a homogeneous sensitivity to the noise sources to be attenuated, as described above. By comparing the two parameters of the desired signal and the noise signal, it can thus be achieved that the result of the comparison, and therefore the corresponding weighting factor for the relevant frequency band, depends only negligibly on the direction of a noise source within the aforementioned half-space. Only the noise level from this half-space significantly influences the outcome of the comparison in the frequency band.

[0031] Spectral components of noise originating from a significantly different direction than the target direction can thus be attenuated from the input signal being processed, preserving a natural sound image. The advantages are not limited to the aforementioned half-space, but, due to continuity and regularity requirements of the signals used, are also effective to a limited extent beyond the exact boundaries of the half-space.

[0032] Preferably, for a second plurality of frequency bands, the weighting factor is calculated based on the preliminary weighting factor and a normalization factor, which is determined as a function of at least one preliminary weighting factor of the second plurality of frequency bands. Preferably, the normalization factor is determined directly, i.e., in particular linearly and preferably identically, from a preliminary weighting factor of one of the frequency bands, optionally after time averaging. Such normalization allows the weighting of the individual frequency bands to be related to each other by normalization, for example, by subjecting all relevant frequency bands to the same normalization. During normalization, individual level peaks can be taken into account, for example, by averaging, so that the weighting factors are not subject to sudden changes due to fluctuations in the normalization, without potentially...Within a given frequency band, a significant instantaneous change in the sound levels of the target signal or the interference signal must be present. Determining the weighting factor as a function of at least one preliminary weighting factor includes, in particular, a time-averaged calculation of the acoustic parameters of the respective target and interference signals underlying the at least one preliminary weighting factor. The normalization factor can also be limited in its value.

[0033] Advantageously, the normalization factor for a frequency band is determined based on a time average of the values ​​of the acoustic parameters used and / or the values ​​of the preliminary weighting factor in the same frequency band, and / or based on a maximum and / or a sum of the values ​​of the preliminary weighting factors and / or a signal level across all relevant frequency bands. This includes, in particular, a time average of the instantaneous maximum of the frequency-band-specific values ​​of the individual preliminary weighting factors and a maximum of the time averages of all relevant frequency bands.

[0034] Normalizing the preliminary weighting factor in a frequency band based on the maximum of the preliminary weighting factor values ​​across all relevant frequency bands offers the advantage, particularly for comparisons using a quotient, that for the frequency band in which the preliminary weighting factor is maximum—i.e., where the target signal contains the most spectral energy compared to the interference signal (and thus its contribution to the desired signal is likely greatest)—the weighting factor assumes the maximum value of 1. A corresponding weighting of the input signal to be processed then results in a signal that remains unchanged by the weighting.Other frequency bands, for which the preliminary weighting factor is not at its maximum, are reduced as a result of normalization, with the reduction being greater the lower the useful signal component in the interference signal is compared to the target signal in the frequency band, and therefore the lower the preliminary weighting factor of the frequency band.

[0035] This approach avoids a hard limitation of the weighting factor to a fixed value, so that direction-dependent differences in the spectrum and level are still maintained for noise and interference signal components, further promoting a natural sound image.

[0036] A particularly advantageous normalization method is to use a time average of the instantaneous maximum of the frequency-band-specific values ​​of the individual preliminary weighting factors, or a maximum of the time averages of all relevant frequency bands. Preferably, a time average is performed over a period of 0.1 s to 1 s. This time averaging prevents background "pumping" in the output signal caused by short-term fluctuations in the desired signal. Alternatively or additionally, normalization can be achieved using a fixed value for the normalization factor, which can depend, in particular, on the attenuation of the noise signal and the absence of a desired signal (detectable by the noise signal and the target signal).This approach has the advantage that in an acoustic environment where there is no useful signal present at any given moment, everything is reduced by the aforementioned fixed value, which is generally perceived as more pleasant due to the noise or interference being the only component of the sound.

[0037] InIn one of two possible embodiments of the invention, a signal with a substantially omnidirectional directional characteristic is generated as the target signal, and a directional signal with a relative attenuation in the target direction is used as the interference signal. The generation of a signal with a substantially omnidirectional directional characteristic here means, in particular, that said directional characteristic results from the signal generation process. This can be achieved, on the one hand, by a signal from an omnidirectional microphone as an input converter, or, on the other hand, by an omnidirectional sum-and-delay or delay-and-subtract signal from an array of input converters.

[0038] Using a directional signal with relative attenuation in the target direction as an interference signal includes, on the one hand, situations where said attenuation results from the signal generation process, e.g., through differential directional microphones using the first and second input transducers. On the other hand, an omnidirectional signal can also be generated (as described above), and the desired attenuation can be achieved, for example, through shadowing effects. In In the sense of the invention and its embodiments, the generation of a signal with a specific directional characteristic thus means in particular the said directional characteristic in the free field as a result of the electroacoustic signal generation, while the use of a signal with a specific directional characteristic can additionally also include a directional characteristic that arises as a result of the spatial circumstances of the use.

[0039] Preferably, the interference signal exhibits maximum, ideally total, attenuation in the target direction; in particular, the interference signal can be generated as an anticardioid-shaped directional signal based on the signals of the first and second input converters by appropriate time-delayed superposition.

[0040] Preferably, the preliminary weighting factor is determined by a quotient of these values ​​and is limited to an upper limit of 6 dB, preferably 12 dB, and particularly preferably 15 dB. This is advantageous when no significant noise components are present in the interim compared to a strong useful signal. In the case of an anticardioid interference signal, such a limitation can also be replaced or supplemented by a notch of finite depth in the anticardioid directional characteristic, which can be achieved, for example, by a complex-valued superposition parameter of the two signals from the input converters.

[0041] In the second embodiment of the invention, a directional signal aligned in the target direction is used as the target signal. This signal has a lobe-shaped directional characteristic and exhibits an attenuation of at least -10 dB in the half-space opposite the target direction. Near-complete attenuation is defined in particular as an attenuation of -10 dB, preferably -15 dB, as is the case, for example, with a signal having a lobe-shaped directional characteristic. In this case, the interfering signal exhibits the most homogeneous sensitivity possible in the aforementioned half-space, e.g., as a cardioid-shaped directional signal (with attenuation in the target direction) or as an omnidirectional signal.

[0042] Advantageously, the interference signal is generated at least by means of a first input converter, which is arranged in a housing that, during normal operation of the hearing device, is at least partially carried behind a pin. Preferably, the second or a further input converter is also arranged in said housing. The interference signal is then preferably formed as a directional signal from the two corresponding input signals of the two input converters (i.e., the first and the second or further input converter). The target signal can, in particular, be formed as an omnidirectional signal from the two input signals generated by the first and second input converters arranged in the housing.

[0043] For comparing the desired signal with the interference signal, a so-called roll-on compensation of the interference signal is preferably performed, e.g., by means of a low-pass filter, if the interference signal is generated as a delay-and-subtract directional signal from the input converter signals, but the target signal is, e.g., a delay-and-sum signal or a signal from only one input converter. The aforementioned low-pass filter can be omitted if the target signal is also generated as a delay-and-subtract signal. Alternatively, the interference signal can be generated from only one input converter by utilizing the natural attenuation effect of the pinna; the target signal is then preferably generated solely by the other input converter, which can, for example, be located at the entrance of the ear canal.

[0044] In particular, the first and second input transducers are both located within the housing, which is, for example, the housing of a BTE or RIC hearing aid. The interfering signal can then be generated using differential directional microphones, and the target signal as a "2-mic omnidirectional" signal.

[0045] Advantageously, the input signal to be processed is generated by an earpiece input converter located in an earpiece which, during normal operation, is worn by the user of the hearing device and at least partially inserted into a concha and / or ear canal. In particular, the earpiece input converter can also be the first or second input converter in such a way that the input signal to be processed is also used to determine the interference and / or the target signal. However, the interference and target signals can also be generated separately from the input signal to be processed, e.g., as described above in a BTE / RIC package.

[0046] In a further advantageous embodiment, the target signal is generated in a device external to the hearing aid. This external device is understood to be part of the hearing system and, as such, is preferably designed to communicate with the hearing aid via a suitable connection. A mobile phone can be used as the external device, which is configured for the method, in particular by a suitable application that controls the mobile phone's microphone as the first input converter and the signal transmission to the hearing aid. The comparison of the desired signal with the interference signal can preferably be performed on the hearing aid after appropriate transmission of the target signal or the acoustic parameter by the mobile phone.Similarly, the interference signal can also be preferably generated by a second input transducer of the hearing aid and then transmitted to the external device for comparison of the acoustic parameters. Furthermore, a dedicated external unit can be used as the external device, e.g., a so-called partner unit for a hearing aid.

[0047] The partner unit is worn on the body by a conversation partner of the hearing aid wearer, e.g., around the neck, or positioned nearby, for example, on a table in front of them, to make contributions to the conversation more audible for the hearing aid wearer. In connection with the present invention, only one input transducer of the partner unit can be used to generate the target signal, since the desired signal—the contributions of the conversation partner located in the immediate vicinity of the partner unit—is amplified in comparison to any background noise and is incorporated into a signal generated by the partner unit.

[0048] Advantageously, the weighting factor is further formed based on a factor that takes into account volume differences and / or time differences and / or spectral differences in the respective frequency band between the first input converter and / or the second input converter and / or the further input converter for generating the input signal to be processed.

[0049] For example, if the interference signal is generated by the first input transducer, which is located in a housing that the wearer carries partially behind the pinna, and the target signal is generated by an input transducer located at the wearer's ear canal, the additional factor can, for example, account for the potentially varying attenuation effect of the pinna across different frequency bands. Furthermore, the factor can incorporate a relative transfer function from the point of interference signal generation (e.g., the housing at or behind the pinna) to the point of target signal generation (e.g., at the ear canal or in an external unit), preferably with respect to the assumed signal source. This allows the weighting factor to compensate for components resulting from differing sound propagation to the point of interference signal generation or the point of target signal generation.

[0050] InIn an advantageous embodiment, the output signal is generated from the input signal to be processed, weighted frequency-bandwise with the respective weighting factors, as well as from another omnidirectional signal and / or another directional signal. Particularly if the frequency-bandwise application of the respective weighting factors to the input signal to be processed leads to artifacts, e.g., due to its spectral distribution, the audibility of artifacts can be reduced by "mixing in" a directional signal (e.g., a cardioid directional signal) with a proportion of, for example, 25%, 30%, or 40% (and a corresponding proportion of the weighted input signal to be processed of 75%, 70%, or 60%), while the natural sound impression is maintained.Likewise, an omnidirectionally generated signal (especially in the aforementioned proportions) can be mixed with the weighted input signal to be processed for the formation of the output signal, which is particularly preferably generated by a different input converter than the input signal to be processed.

[0051] It is further advantageous if, with respect to a first useful signal source arranged in a first target direction, first weighting factors are determined frequency-bandwise, and second weighting factors are determined frequency-bandwise with respect to a second useful signal source arranged in a second target direction, and wherein the input signal to be processed is weighted in the respective frequency band on the basis of a weighting factor which is formed on the basis of the respective first weighting factor and on the basis of the respective second weighting factor, preferably as an average or as a product.

[0052] This means, in particular, that initial weighting factors are determined with respect to a first useful signal source. This is done by comparing acoustic characteristics obtained in the respective frequency bands from a first interference signal and a first target signal, both referenced to the first useful signal source. For example, the first interference signal exhibits a relative, and especially the greatest possible, attenuation in a first target direction, which is preferably defined by the direction of the first useful signal source. Furthermore, second weighting factors are determined for the input signal to be processed with respect to a second useful signal source, which differs from the first useful signal source and, in particular, occupies a second target direction that differs from the first target direction.

[0053] This is also done by comparing acoustic parameters, which are obtained in the respective frequency bands from a second interfering signal and a second target signal, which in turn are referenced to the second useful signal source. For example, the second interfering signal exhibits a relative and, in particular, the greatest possible attenuation in the second target direction. The weighting factors to be applied to the input signal to be processed are then determined frequency band by frequency based on the first weighting factors (i.e., with respect to the first useful signal source) and on the second weighting factors (i.e., with respect to the second useful signal source), preferably based on a product or an arithmetic mean value, possibly weighted by the sound power of the respective useful signal sources, and in particular by a suitable global normalization.

[0054] Preferably, the hearing system includes a further hearing device, wherein at least for one frequency band in the hearing device the preliminary weighting factor is determined, a contralateral preliminary weighting factor is transmitted to the hearing device from the further hearing device, and the weighting factor or a weighting factor for a contralateral input signal transmitted by the further hearing device is determined by comparing the preliminary weighting factor with the contralateral preliminary weighting factor.

[0055] In this case, the hearing system is specifically a binaural hearing aid system, with the hearing device and the other hearing device each being a single hearing aid worn on one ear. The contralateral input signal is then an input signal for one hearing aid, which is generated in the other hearing device and transmitted for binaural signal processing. The contralateral preliminary weighting factor is preferably generated in the other hearing device in the same way as the preliminary weighting factor in the hearing device. The weighting factor to be applied by the hearing device is then determined by comparing the "local" preliminary weighting factor generated in the hearing device with the contralateral preliminary weighting factor from the other hearing device.This approach allows, particularly for a binaural hearing aid system, the preliminary weighting factors of both sides to be "synchronized" in individual frequency bands, so that a distortion of, for example, the "Interaural Level Difference" can be prevented by using, for example, an average of the preliminary weighting factors of both sides for the weighting factor (or, if necessary, a slightly stronger weighting of the local preliminary weighting factor compared to the contralateral preliminary weighting factor, e.g., 0.6 to 0.4 or 0.7 to 0.3).

[0056] Preferably, the contralateral preliminary weighting factor is transmitted to the hearing device as a discrete value with a range of three values, and the value of the preliminary weighting factor is assigned to the contralateral weighting factor if the deviation of the contralateral preliminary weighting factor from the preliminary weighting factor does not exceed a predetermined limit. In particular, this means that the contralateral preliminary weighting factor is preferably discretized to three values ​​or a few more and is compared with the "locally" available preliminary weighting factor, whose range may initially include even more values.This range of values ​​for the local preliminary weighting factor can now be mapped to coarser intervals for comparison with the contralateral preliminary weighting factor (preferably the same number as the range of values ​​of the contralateral preliminary weighting factor), so that the local preliminary weighting factor is assigned as the weighting factor – and possibly normalized – if the contralateral preliminary weighting factor lies in the same "coarser interval" as the "local" preliminary weighting factor. If this is not the case, the weighting factor can be calculated by averaging the preliminary weighting factors.

[0057] The invention further describes a hearing system with a hearing device, wherein the hearing system comprises at least two input converters for generating an interference signal, a target signal, and an input signal to be processed, wherein the hearing device comprises at least one output converter, and wherein the hearing system comprises a control unit configured to carry out the aforementioned method. The hearing system according to the invention shares the advantages of the method according to the invention. The advantages specified for the method and its further developments can be transferred analogously to the hearing system.

[0058] The above description applies analogously to the generation of the interference signal and the target signal using the at least two input converters with regard to the method according to the invention. The input signal to be processed can be generated either using one or both input converters, which are also used for generating the interference signal and the target signal, or using a further input converter of the hearing system.

[0059] The control unit is preferably implemented in the hearing device. If the hearing device is a binaural hearing aid system, the control unit can also be comprised of all signal processing units in both local units of the binaural system. To carry out the aforementioned procedure, the hearing system can, in particular, include an external unit that is not considered part of the hearing device, such as a mobile phone or similar device with an input converter, which is specifically configured to generate the target signal and / or the interference signal, and optionally with a signal processing unit, which in this case can also form part of the aforementioned control unit.

[0060] Preferably, the hearing device is designed as a hearing aid. The application of the method described above is particularly advantageous for a hearing aid that is specifically designed and configured to compensate for a hearing impairment or hearing loss of its wearer.

[0061] Preferably, the hearing aid comprises a housing in which a first input transducer and a second input transducer are arranged, wherein the hearing aid includes an earpiece in which a further input transducer for generating the input signal to be processed is arranged, and wherein the control unit is configured to generate the interference signal and the target signal based on the signals from the first and second input transducers. This allows the interference signal and / or the target signal to be generated efficiently and with pinpoint accuracy using directional microphones for obtaining the frequency-band-dependent weighting factors for the input signal to be processed, thus enabling particularly good noise reduction.In this process, the input signal to be processed is generated at the wearer's ear canal, and thus contains particularly natural spatial information of the wearer's acoustic environment, while maintaining the natural shadowing effect of the pinna for the input signal to be processed, which further enhances the natural spatial hearing impression.

[0062] An embodiment of the invention is explained in more detail below with reference to the drawings. The drawings schematically depict: Fig. 1A A side view of a hearing aid with a housing and an earpiece, wherein two input transducers are arranged in the housing and one in the earpiece, Fig. 1B the hearing aid according to Fig. 1A , wherein only one input converter is arranged in the housing, Fig. 2 shows a block diagram of noise reduction in the hearing aid according to Fig. 1Aby means of weighting factors which are determined by directional microphones, Fig. 3 shows a directional dependence of preliminary weighting factors in the hearing aid according to Fig. 2 Fig. 4 shows a hearing system with a hearing aid and a mobile phone, and Fig. 5 shows a block diagram of a system for Fig. 2 alternative noise reduction in hearing aids Fig. 1A .

[0063] Corresponding parts and sizes are marked with the same reference symbols in all figures.

[0064] In Figure 1AA schematic side view of a hearing system 2 formed by a hearing device 1 is shown. The hearing device 1 is, in this case, a hearing aid 4. The hearing aid 4 has a housing 6 and an earpiece 8 connected to the housing 6. The hearing aid 4 is designed as a RIC (Receiver-in-Canal) device, which has an output transducer 10, designed as a loudspeaker, at the end of the earpiece 8. The earpiece 8 is mechanically connected to the housing 6 via a connection 12. A signal connection 14 also runs along this connection 12, which electronically connects the output transducer 10 to a signal processing unit 16 in the housing 6 (dashed line), as will be described later. The signal processing unit 16 forms a control unit 18 for the hearing system 2 and is, in particular, defined by one or more signal processors, each with its own dedicated working memory.In housing 6, a first input converter 21 and a second input converter 22 are arranged slightly apart from each other, and each is electronically connected to the control unit 18 (dashed line).

[0065] In operation of the hearing aid 4, input signals (not shown) are generated by the first and second input transducers 21 and 22, respectively, and output to the signal processing unit 16. There, they are processed according to the individual audiological specifications and requirements of the hearing aid 4 user, and in particular, amplified and, if necessary, compressed depending on the frequency. The signal processing unit 16 outputs a corresponding output signal (not shown) via the signal connection 14 to the output transducer 10, which converts this output signal into an output sound (not shown) that is delivered to the user's ear. Due to the spatial distance between the first and second input transducers 21 and 22, spatial processing of the output signal is also possible in the signal processing unit 16 using directional microphones.This makes it possible to selectively emphasize a useful signal in the vicinity of the carrier, usually provided by speech contributions from a conversation partner of the carrier, using said directional microphones, or to selectively reduce ambient noise and / or other sound sources away from the useful signal source using directional microphones.

[0066] However, with this direction-sensitive signal processing, information important for spatial hearing perception can be lost for the wearer. The present hearing aid 4 is therefore designed to determine frequency-dependent weighting factors from the signals of the first and second input transducers 21, 22, in a manner to be described later. These weighting factors are used to weight an a priori preferably omnidirectional input signal to be processed in the signal processing unit 16, whereby the weighting factors are intended to provide advantageous noise reduction across individual frequency bands. The signal 24 generated by the first input transducer 21 can be used as an input signal to be processed.

[0067] Alternatively, the hearing aid 4 can also have a further input transducer 26 in the earpiece 8, and the input signal to be processed can then be provided by the signal of said further input transducer 26. This has the advantage that, when the hearing aid 4 is worn as intended, with the housing 6 being worn at least partially behind the pinna of one of the wearer's ears, and the earpiece 8 being inserted with the end of the output transducer 10 into the entrance of the corresponding ear canal, the further input transducer 26 is located in the area of ​​the entrance of the ear canal, and thus the signal generated by the further input transducer 26 exhibits essentially the same behavior with regard to a shadowing effect of the head and, in particular, the pinna of the wearer as sound which reaches the wearer's ear without the presence of the hearing aid 4.

[0068] In Figure 1Bschematically shown in a side view is an alternative design of the hearing device 1 according to Figure 1A depicted. Also in Figure 1B The hearing device 1 consists of a hearing aid 4 designed as a RIC (Receiver-in-Canal) device, comprising a housing 6 that is worn partially behind the pinna during operation and an earpiece 8. A first input transducer 21 is arranged in the housing 6 and is in signal communication with a control unit 18, also located in the housing 6. An output transducer 10 is arranged in the earpiece 8 and is connected to the control unit 18 via a signal connection 14, the signal connection 14 running along the mechanical connection 12 between the housing 6 and the earpiece 8. The free end of the earpiece 8 is inserted into the opening of the wearer's ear canal for operation of the hearing aid 4.

[0069] A second input transducer 22 is arranged in the earpiece 8. Based on the signal from the first and the second input transducers 21, 22, analogous to the hearing aid 4, Figure 1A Frequency-dependent weighting factors are determined in a manner yet to be described, by means of which the input signal to be processed, generated in the present example by the second input converter 22, is weighted in the control unit 18 for noise suppression. A significant difference to the in Figure 1A The hearing aid 4 shown here therefore consists in the fact that the second input transducer 22, whose signal is used to determine the frequency-dependent weighting factors, is located in the earpiece 8 (and not, like the first input transducer 21, in the housing 6).

[0070] The hearing aid 4 after Figure 1A or after Figure 1BThe device can also be configured as a BTE device, in which case the connection 12 is formed by the sound tube of the BTE device. In particular, the second input transducer 22 can be arranged in the housing 6 of the BTE device. If the second input transducer (or the further input transducer 26) is located... Figure 1A If the signal processing unit 16 is arranged in or on the earpiece 8 (whose free end in a BTE device is formed, for example, by a dome or an earmold), the signal connection 14 to the control unit 18 in the housing 6 runs along the sound tube, preferably in a dedicated cable. In particular, a signal processing unit 16, as part of the control unit 18, can also be arranged in the earpiece 8. If the earpiece 8 has an input transducer, the hearing aid 4 can, in particular, be a combination of a BTE or RIC device with an ITE or CIC device.

[0071] In Figure 2The hearing system 1 formed by the hearing aid 4 is shown schematically in a block diagram. Figure 1A The hearing aid 4 is illustrated with the signal processing for noise reduction already described. It comprises the first input transducer 21 and the second input transducer 22, which is located at a distance D from the first input transducer. The first input transducer 21 generates a first signal 31, and the second input transducer 22 generates a second signal 32 from ambient sound (not shown in detail). Possible pre-amplification and pre-processing, such as broadband compression and A / D conversion, are already integrated into the function of the first and second input transducers 21 and 22, respectively.

[0072] The first and second signals 31, 32 are each transformed into the time-frequency domain in filter banks 33, 34. The first signal 31, thus filtered, is then delayed by a time constant T in each frequency band, optionally further filtered with a complex transfer function (not shown) which can take into account possible level and / or phase differences between the two input converters 21, 22, and subtracted from the filtered signal 32, and subsequently filtered with a low-pass filter 35. The low-pass filtering is performed because the subtraction attenuates low-frequency signal components, since the time constant T, as the acoustic propagation delay between the two input converters 21, 22 due to the distance D, causes low-frequency signal components to still have similar amplitudes at both input converters 21, 22 despite propagation.

[0073] The aforementioned low-pass filtering now results in a noise signal 36, which, due to the time delay T before the subtraction of the two input signals 31, 32, which corresponds exactly to the acoustic travel time for the distance D, essentially has an anticardioid-shaped directional characteristic 64 in each frequency band, the maximum attenuation of which points in a target direction 38, which is given by a connecting line from the second input transducer 22 to the first input transducer 21, and coincides with the frontal direction when the hearing aid 4 is worn as intended.

[0074] The second signal 32, decomposed into individual frequency bands by the filter bank 34, exhibits essentially an omnidirectional directional characteristic 63 as a microphone signal for each frequency band. This second signal 32 is now used as the target signal 40. An acoustic parameter 42 is determined for each of the target signal 40 and the interference signal 36 in each frequency band, which is intended to provide information about the energy content of the respective signal in the respective frequency band. This is ensured here by selecting the absolute magnitude of the respective signal as the acoustic parameter 42. In particular, however, a signal power or a signal level, or a monotonic function, e.g., quadratic or logarithmic, of the signal power, the absolute magnitude, or the signal level can also be used as the parameter 42. Time averages 48 and 49 are then calculated for smoothing from the absolute magnitude 44 of the interference signal 36 and the absolute magnitude 46 of the target signal 40, respectively.A quotient 50 is then calculated from the time average 49 of the absolute magnitude 46 of the target signal 40 as the numerator and the time average 48 of the absolute magnitude 44 of the interference signal 36 as the denominator. This quotient, which may optionally be further limited to an upper limit of, for example, 6 dB or higher (e.g., 12 dB or 15 dB), forms a preliminary weighting factor 51 for the respective frequency band.

[0075] A maximum of 52 of the preliminary weighting factors 51 is now determined across all frequency bands and set as the normalization factor 52. The preliminary weighting factors 51 are normalized over the normalization factor 52 thus determined, resulting in a weighting factor 54 for each frequency band.

[0076] An input signal 56 to be processed is generated by the input converter 26. The input signal 56 to be processed is transformed into the time-frequency domain by a filter bank 57. The filter banks 33, 34, and 57 preferably have identical frequency resolution and identical slope.

[0077] The weighting factor 54 is then applied multiplicatively to the transformed input signal 56 to be processed. From the frequency-band-wise signal components of the input signal 56 to be processed, weighted as described, a broadband output signal 58 is generated, for example, by means of an inverse fast Fourier transform. This output signal is then converted into an output sound 60 by the output converter 10. Before the generation of the output signal 58, additional signal processing (not shown in detail) can take place. This processing may include, for example, a frequency-band-wise reduction or increase of the signal contributions depending on the individual audiological requirements of the user and / or additional measures for suppressing background noise and / or acoustic feedback.In particular, for the application of the weighting factor 54 to the input signal 56 to be processed in the respective frequency band, an absolute magnitude and a phase can first be determined from the input signal 56 to be processed, whereby the application of the weighting factor 54 is only made to the absolute magnitude, and the phase is used for a reverse transformation to generate the output signal 58.

[0078] For an application of the based on Figure 2 The noise reduction shown applies to hearing aid 4. Figure 1BThe input signal 56 to be processed is generated by the first or the second input transducer 21 or 22, respectively. The directional signal 56 to be processed thus corresponds to the first or second signal 31 or 32, respectively. In general, other alternative configurations of the hearing aid 4 are also conceivable for noise reduction, for example, a so-called ITE hearing aid with two input transducers arranged in the area of ​​the ear canal as the first and second input transducers 21, 22 for generating the two signals 31, 32 as well as the input signal 56 to be processed.

[0079] In Figure 3 The schematic and simplified top view illustrates the effect of the preliminary weighting factor 51 according to Figure 2The diagram illustrates the effects of sound signals from different spatial directions. The left image shows a carrier 62 of the hearing aid 4 and the omnidirectional directional characteristic 63 of the target signal 40 surrounding it. The middle image shows the same carrier 62 again, this time with the anticardioid directional characteristic 64 of the interference signal 36, which exhibits its maximum attenuation in the target direction 38. It can be immediately seen that for a sound signal from the half-space 66 opposite the target direction 65, there is no significant attenuation by the interference signal 36, since the anticardioid directional characteristic 64 there is essentially homogeneous and similar to the omnidirectional directional characteristic 63.

[0080] The right-hand image illustrates the directional dependence 68 of the preliminary weighting factor 51, as schematically inferred from the two directional characteristics 63 and 64. While in the rear half-space 66 the target signal 40 and the interfering signal 36 exhibit largely similar sensitivities to sound signals, the preliminary weighting factor 51 is essentially homogeneous and thus direction-independent in this area. Only with increasing approach to the target direction 38 do the differences in the two directional characteristics 63 and 64 become increasingly noticeable, resulting in a pronounced bulge in the preliminary weighting factor 51 in the target direction 38. This bulge can be limited to a finite value, particularly by compression or limiting.

[0081] As a result of the significant increase in the target direction 38, it is now possible to determine, based on Figure 2The described procedure, using normalization over the maximum 52 of all preliminary weighting factors 51, ensures that the weighting factor 54 is exactly 1 only in the frequency band where the maximum spectral component of the useful signal from the target direction 38 is present. As a result of dividing the preliminary weighting factors 51 by the normalization factor 52, a reduction occurs for other frequency bands due to the weighting factor 54. This reduction is greater the lower the spectral component of the useful signal from the target direction 38 is in the respective frequency band.

[0082] In Figure 4 is schematically shown in a top view, with regard to the in Fig. 1A and 1BThe variants shown represent alternative configurations of the hearing system 2, which comprises a hearing device 1 and an external device 70. The external device 70 is a mobile phone 71. The hearing device 1 is a hearing aid 4, which is worn by the user 62 on one ear (not shown in detail). The hearing aid 4 has at least one first input transducer 21 and can, for example, be designed as an ITE device. The mobile phone 71 is positioned directly in front of the user 62's conversation partner 74 in such a way that a microphone of the mobile phone, acting as the second input transducer 22 of the hearing system 1, can record the speech contributions 75 of the conversation partner 74 unimpeded and with exceptional clarity.

[0083] In order to better suppress noise, e.g., in the form of interference from the unspecified directional sources 76, 78, or diffuse background noise (not shown in detail) by the hearing aid 4, frequency-dependent weighting factors are generated from the signals of the first input transducer 21 in the hearing aid 4 and the second input transducer 22 in the mobile phone 71, in a manner to be described later. These weighting factors are then applied to the signal of the first input transducer 21 in the hearing aid 4. The weighting factors are generated in such a way that the spectral components of the interference sources 76, 78 (or diffuse background noise) in the signal of the first input transducer 21, which ultimately represents the total sound arriving there, are reduced as much as possible by the weighting process.Furthermore, the spectral components of the speech contributions 35 should be preserved as far as possible by weighting and, in particular, increased relative to the background noise of the sources of interference 76, 78.

[0084] This is achieved by deriving the weighting factors frequency-band by frequency based on a target signal and an interference signal, whereby the target signal should contain the highest possible relative proportion of the desired signal (referring, for example, to the total energy in a frequency band), i.e., in this case, the speech contributions 75, and the interference signal the lowest possible relative proportion of the desired signal. Likewise, the degree of suppression of the interference sources 76, 78 should preferably depend only on their loudness, and not on their direction. This requirement is now achieved by using the signal from the first input converter 21 as the interference signal and the signal from the second input converter 22 as the target signal.As a result of the positioning of the mobile phone 71, the signal of the second input transducer 22 has a particularly high proportion of speech contributions 75 from the conversation partner 74, while solely due to the spatial distance of the carrier 62 from the conversation partner 74, the first input transducer 21 in the hearing aid 4 will receive a lower proportion of speech contributions 75, and therefore higher spectral components of the interference sources 76, 78 are recorded in its signal.

[0085] In particular, the hearing system 2 can also be designed as a binaural hearing aid system, which, in addition to the hearing aid 4, has another hearing aid (not shown) with the second input transducer, which is to be worn by the wearer 62 on the other ear. In For this additional hearing aid, preliminary weighting factors 51 can be determined in a manner already described, similar to hearing aid 4 (see above). Figure 2These preliminary weighting factors, which are then contralateral to the hearing aid 4, are transferred to the hearing aid 4, where, on the one hand, the weighting factors of the individual frequency bands to be applied locally in the hearing aid 4 can be generated by comparing the local preliminary weighting factors with the contralateral preliminary weighting factors.

[0086] On the other hand, the contralateral preliminary weighting factors can also be used within the framework of binaural signal processing, for example, if a signal to be processed is also transmitted from the (contralateral) additional hearing aid to hearing aid 4. Weighting factors to be applied to the contralateral signal from the additional hearing aid in hearing aid 4 within the framework of binaural signal processing are then calculated based on the contralateral preliminary weighting factors.

[0087] In Fig. 5schematically shown in a block diagram is an alternative to noise reduction according to Fig. 2 for the hearing aid 4 shown there. Up to the formation of the quotient 50 from the absolute value 46 of the useful signal 40 as the numerator and the absolute value 44 of the interference signal 36 as the denominator, the signal processing can proceed essentially identically (the low-pass filter 35 for the interference signal 36 has not been shown for the sake of simplicity), whereby in this case the input signal 56 to be processed is additionally given by the second signal 32 in the time-frequency domain (and thus the useful signal 40). However, the first signal 31 (in the time-frequency domain) or the signal of another input converter 26 (which in the exemplary embodiment according to Fig. 5 (is not intended) to be used.

[0088] Unlike the one based on Fig. 2In the illustrated embodiment, the weighting factor 54 can also be generated in the individual frequency bands by mapping the quotient 50 to a discrete range of values ​​80, for example, consisting of three values ​​80a, 80b, 80c, for the preliminary weighting factor 51. For example, an upper, a middle, and a lower interval 82a, 82b, 82c are defined for the quotient 50, each of which is mapped to the largest value 80a (e.g., 1 or 1.3 or a value in between), the middle value 80b (e.g., 0.75 or similar), and the smallest value 80c (e.g., 0.5 or less), respectively, for the preliminary weighting factor 51. The preliminary weighting factor 51 generated in this way can also be smoothed over time. Normalization (not shown) is also possible (especially if a value ≠ 1 is defined as the largest value of the discrete range of values).

[0089] Similarly (not shown), the acoustic parameter 42 of the target signal 40, i.e., its absolute value 46 in this example, and the corresponding acoustic parameter 42 of the interference signal 36, i.e., its absolute value 44 in this example, can also be subjected to a greater-than / less-than comparison. If the absolute value 46 of the target signal 40 is greater than the absolute value 44 of the interference signal 36, the largest value 80a of the specified discrete value range 80 is assigned as the preliminary weighting factor 51. However, if the absolute value 44 of the interference signal 36 is greater, the absolute value 46 of the target signal 40 is scaled by a factor > 1 (e.g., 1.1 or 1.2) and compared again with the absolute value 44 of the interference signal 36. If the absolute value 46 of the target signal 40 is now greater, the middle value 80b of the discrete range of values ​​80 is assigned as the preliminary weighting factor 51; otherwise, the smallest value 80c is assigned.The aforementioned cascaded greater-than-less-than comparisons with intermediate scaling can mathematically also be formulated as the mapping of the quotient 50 to the discrete range of values ​​80 for the preliminary weighting factor 51 described above, but in practice they are sometimes easier to implement, e.g., on hard-wired circuits.

[0090] Although the invention has been illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples and other variations can be derived by the person skilled in the art without departing from the scope of protection of the invention as defined in the claims. Reference symbol list

[0091] 1 Hearing device 2 Hearing system 4 Hearing aid 6 Housing 8 Earpiece 10 Output converter 12 Connection 14 Signal connection 16 Signal processing unit 18 Control unit 21 First input converter 22 Second input converter 24 Input signal 26 Second input converter 31 First signal 32 Second signal 33 Filter bank 34 Filter bank 35 Low-pass filter 36 Interference signal 38 Target direction 40 Target signal 42 Acoustic parameter 44 Absolute magnitude of the interference signal 46 Absolute magnitude of the target signal 48 Time average 49 Time average 50 Quotient 51 Preliminary weighting factor 52 Maximum / Normalization factor 54 Weighting factor 56 Input signal to be processed 57 Filter bank 58 Output signal 60 Output sound 62 Carrier 63 Omnidirectional directional characteristic 64 Anticardioid-shaped directional characteristic 66 Half-space 68 Directional dependence 70 External device 71 Mobile phone 74 Conversation partner 75 Speech contributions 76 Source of interference 78 Source of interference 80 Discrete value range 80a Largest value 80b Medium value 80 Smallest value 82a Upper interval 82b Medium interval82cunteres Intervall

Claims

1. Method for direction-dependent noise rejection for a hearing system (2) comprising a hearing apparatus (1), - wherein at least one first input transducer (21) of the hearing system (2) and a second input transducer (22) of the hearing system (2) are used to generate an interference signal (36) and a target signal (40) from a sound from the surroundings, the interference signal (36) and / or the target signal (40) being referenced to a useful signal source arranged in a target direction (38), - wherein the target signal (40) is generated with a target directivity pattern that has a homogeneous characteristic over a half-space (66) opposite the target direction (38), - wherein, for each of at least one first plurality of frequency bands, an acoustic characteristic (42, 46) of the target signal (40) is compared with a corresponding acoustic characteristic (42, 44) of the interference signal (36), and said comparison is used to ascertain a provisional weighting factor (51), the range of values (80) of which comprises at least three values (80a, 80b, 80c), the provisional weighting factor (51) being used to form for the frequency band a weighting factor (54) for the respective frequency band in each particular case, wherein an input signal (56) to be processed for the hearing system (2) is weighted on a frequency-band-by-frequency-band basis using the respective weighting factor (54), and the thus weighted input signal (56) to be processed is used to generate an output signal (58), and wherein the target signal (40) generated is a signal having a substantially omnidirectional directivity pattern (63), and the interference signal (36) used is a directional signal having a relative attenuation in the target direction (38).

2. Method for direction-dependent noise rejection for a hearing system (2) comprising a hearing apparatus (1), - wherein at least one first input transducer (21) of the hearing system (2) and a second input transducer (22) of the hearing system (2) are used to generate an interference signal (36) and a target signal (40) from a sound from the surroundings, the interference signal (36) and / or the target signal (40) being referenced to a useful signal source arranged in a target direction (38), - wherein, for each of at least one first plurality of frequency bands, an acoustic characteristic (42, 46) of the target signal (40) is compared with a corresponding acoustic characteristic (42, 44) of the interference signal (36), and said comparison is used to ascertain a provisional weighting factor (51), the range of values (80) of which comprises at least three values (80a, 80b, 80c), the provisional weighting factor (51) being used to form for the frequency band a weighting factor (54) for the respective frequency band in each particular case, wherein an input signal (56) to be processed for the hearing system (2) is weighted on a frequency-band-by-frequency-band basis using the respective weighting factor (54), and the thus weighted input signal (56) to be processed is used to generate an output signal (58), and wherein the target signal (40) used is a directional signal that is oriented in the target direction (38) and that has a lobe-shaped directivity pattern, and has an attenuation of at least -10 dB in the half-space (66) opposite the target direction (38), and the interference signal used is a cardioid directional signal having an attenuation in the target direction or an omnidirectional signal.

3. Method according to Claim 1 or according to Claim 2, wherein the weighting factor (54) is formed for each of a second plurality of frequency bands using the provisional weighting factor (51) and using a normalization factor (52) that is determined on the basis of at least one provisional weighting factor of the second plurality of frequency bands.

4. Method according to Claim 3, wherein the normalization factor (52) for a frequency band is determined - using a temporal average of the values of the acoustic characteristics (42) used and / or of the values of the provisional weighting factor (51) in the same frequency band, and / or - using a maximum (52) and / or a sum of the values of the provisional weighting factors (51) and / or of a signal level over all relevant frequency bands.

5. Method according to one of the preceding claims, wherein a quotient (50) is formed for each of at least some frequency bands of the first plurality using the acoustic characteristic (42, 46) of the target signal (40) as numerator and using the corresponding acoustic characteristic (42, 44) of the interference signal (36) as denominator, and the respective quotient (50) is used to form the provisional weighting factor (51).

6. Method according to Claim 5, wherein the quotient (50) for each of the relevant frequency bands is mapped monotonously to a range of values (80) comprising at least three discrete values (80a, 80b, 80c) to form the provisional weighting factor (51).

7. Method according to one of the preceding claims, wherein for at least some frequency bands of the first plurality - the acoustic characteristic (42, 46) of the target signal (40) and the corresponding acoustic characteristic (42, 44) of the interference signal (36) are subjected to a plurality of magnitude comparisons, - wherein one of the two characteristics is scaled differently for the individual magnitude comparisons, and - wherein the magnitude comparisons are used to assign the respective value from the discrete, at least three-valued range of values (80) to the provisional weighting factor (51).

8. Method according to one of the preceding claims, wherein the interference signal (36) is generated at least using a first input transducer (21) arranged in a housing (6), at least part of which is worn behind an auricle by a wearer (62) of the hearing apparatus (1).

9. Method according to one of the preceding claims, wherein the input signal (56) to be processed is generated by an earpiece input transducer (26) arranged in an earpiece (8), at least part of which is worn inserted in a concha and / or an ear canal by the wearer (62) of the hearing apparatus (1).

10. Method according to one of the preceding claims, wherein the target signal (40) is generated in a device (70) that is external with respect to the hearing apparatus (1).

11. Method according to one of the preceding claims, wherein the weighting factor (54) is also formed in each particular case using a factor that takes into consideration volume differences and / or delay differences and / or spectral differences in the respective frequency band between the first input transducer (21) and / or the second input transducer (22) and / or a further input transducer (26) for generating the input signal (56) to be processed.

12. Method according to one of the preceding claims, wherein the output signal (58) is formed using the input signal (56) to be processed, having been weighted with the respective weighting factors (54) on a frequency-band-by-frequency-band basis, and a further omnidirectional signal and / or a further directional signal.

13. Method according to one of the preceding claims, wherein first weighting factors are ascertained on a frequency-band-by-frequency-band basis with regard to a first useful signal source arranged in a first target direction (38), wherein second weighting factors are ascertained on a frequency-band-by-frequency-band basis with regard to a second useful signal source arranged in a second target direction, and wherein the input signal (56) to be processed is weighted in the respective frequency band using a weighting factor (54) that is formed using the respective first weighting factor and using the respective second weighting factor.

14. Method according to one of the preceding claims, wherein the hearing system (2) has a further hearing apparatus, wherein at least for one frequency band - the provisional weighting factor (51) is ascertained in the hearing apparatus, - a contralateral provisional weighting factor is transmitted to the hearing apparatus (1) by the further hearing apparatus, and - the weighting factor or a weighting factor for a contralateral input signal transmitted by the further hearing apparatus is ascertained by means of a comparison of the provisional weighting factor (51) with the contralateral provisional weighting factor.

15. Method according to Claim 14, wherein the contralateral provisional weighting factor is transmitted to the hearing apparatus (1) as a discrete value having a range of values of three values, and wherein the value of the provisional weighting factor is assigned to the contralateral weighting factor if a deviation in the contralateral provisional weighting factor from the provisional weighting factor does not exceed a predefined limit value.

16. Hearing system (2) having a hearing apparatus (1), wherein the hearing system (2) comprises at least two input transducers (21, 22, 26) for generating an interference signal (36), a target signal (40) and an input signal (56) to be processed, wherein the hearing apparatus (1) comprises at least one output transducer (10), and wherein the hearing system (2) comprises a control device (18) that is set up to carry out the method according to one of the preceding claims.

17. Hearing system (2) according to Claim 16, wherein the hearing apparatus (1) is in the form of a hearing device (4).

18. Hearing system (2) according to Claim 17, wherein the hearing device (4) comprises a housing (6) in which a first input transducer (21) and a second input transducer (22) are arranged, wherein the hearing device (4) comprises an earpiece (8) in which a further input transducer (26) for generating the input signal (26) to be processed is arranged, and wherein the control device (18) is set up to use the signals from the first input transducer (21) and the second input transducer (22) to form the interference signal (36) and the target signal (40).