Method for direction-dependent noise rejection for a hearing system containing a hearing apparatus and hearing system

Abstract

In a method for direction-dependent noise rejection for a hearing system, first and second input transducers are used to generate an interference signal and a target signal from a sound from the surroundings. The interference signal and/or the target signal are referenced to a useful signal source arranged in a target direction. The target signal is generated with a target directivity pattern. For each of a first plurality of frequency bands, an acoustic characteristic of the target signal is compared with a corresponding acoustic characteristic of the interference signal, and the comparison is used to ascertain a provisional weighting factor. The provisional weighting factor is used to form for the frequency band a weighting factor for the respective frequency bands. An input signal to be processed is weighted on a frequency-band-by-frequency-band basis using the respective weighting factor, and the weighted input signal is used to generate an output signal.

Claims

1. A method for direction-dependent noise rejection for a hearing system having a hearing apparatus, which comprises the steps of: using at least one first input transducer of the hearing system and a second input transducer of the hearing system to generate an interference signal and a target signal from a sound from surroundings, the interference signal and/or the target signal being referenced to a useful signal source disposed in a target direction; generating the target signal with a target directivity pattern that has a homogeneous or substantially homogeneous characteristic over a half-space opposite the target direction; comparing, for each of at least one first plurality of frequency bands, an acoustic characteristic of the target signal with a corresponding acoustic characteristic of the interference signal, and a comparison is used to ascertain a provisional weighting factor, a range of values of which containing at least three values, the provisional weighting factor being used to form for a frequency band a weighting factor for a respective frequency band in each particular case; and weighting an input signal to be processed for the hearing system on a frequency-band-by-frequency-band basis using the respective weighting factor resulting in a weighted input signal, and the weighted input signal to be processed is used to generate an output signal.

2. The method according to claim 1, wherein the weighting factor is formed for each of a second plurality of frequency bands using the provisional weighting factor and using a normalization factor that is determined on a basis of at least one provisional weighting factor of the second plurality of frequency bands.

3. The method according to claim 2, wherein the normalization factor for a frequency band is determined using a temporal average of values of the acoustic characteristics used and/or of values of the provisional weighting factor in a same frequency band; and/or which further comprises using a maximum and/or a sum of the values of the provisional weighting factors and/or of a signal level over all relevant frequency bands.

4. The method according to claim 1, which further comprises forming a quotient for each of at least some of the frequency bands of the first plurality using the acoustic characteristic of the target signal as numerator and using the corresponding acoustic characteristic of the interference signal as denominator, and the quotient is used to form the provisional weighting factor.

5. The method according to claim 4, wherein the quotient for each of the frequency bands determined to be relevant frequency bands is mapped monotonously to the range of values containing the at least three values (80a, 80b, 80c), being discrete values, to form the provisional weighting factor.

6. The method according to claim 1, wherein 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 magnitude comparisons; one of the two acoustic characteristics is scaled differently for individual ones of the magnitude comparisons; and the magnitude comparisons are used to assign a respective value from the at least three values of the range of values to the provisional weighting factor.

7. The method according to claim 1, wherein: the target signal generated is a signal having a substantially omnidirectional directivity pattern; and the interference signal used is a directional signal having a relative attenuation in the target direction.

8. The method according to claim 1, wherein the target signal used is a directional signal that is oriented in the target direction and that has an almost complete attenuation in the half-space opposite the target direction.

9. The method according to claim 1, wherein the interference signal is generated at least using the first input transducer disposed in a housing, at least part of which is worn behind an auricle by a wearer of the hearing apparatus.

10. The method according to claim 1, wherein the input signal to be processed is generated by an earpiece input transducer disposed in an earpiece, at least part of which is worn inserted in a concha and/or an ear canal by a wearer of the hearing apparatus.

11. The method according to claim 1, wherein the target signal is generated in a device that is external with respect to the hearing apparatus.

12. The method according to claim 1, wherein the weighting factor 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 at least one first input transducer and/or the second input transducer and/or a further input transducer for generating the input signal to be processed.

13. The method according to claim 1, wherein the output signal is formed using the input signal to be processed, having been weighted with weighting factors on a frequency-band-by-frequency-band basis, and a further omnidirectional signal and/or a further directional signal.

14. The method according to claim 1, wherein: first weighting factors are ascertained on a frequency-band-by-frequency-band basis with regard to a first useful signal source disposed in a first target direction; second weighting factors are ascertained on a frequency-band-by-frequency-band basis with regard to a second useful signal source disposed in a second target direction; and the input signal to be processed is weighted in the respective frequency band using the weighting factor that is formed using a respective said first weighting factor and using a respective said second weighting factor.

15. The method according to claim 1, wherein: the hearing system has a further hearing apparatus; at least for one frequency band, the provisional weighting factor is ascertained in the hearing apparatus; a contralateral provisional weighting factor is transmitted to the hearing apparatus 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 with the contralateral provisional weighting factor.

16. The method according to claim 15, wherein: transmitting the contralateral provisional weighting factor to the hearing apparatus as a binary value; and a 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.

17. A hearing system, comprising: at least first and second input transducers for generating an interference signal, a target signal and an input signal to be processed; a hearing apparatus having at least one output transducer; and a controller for performing a method for direction-dependent noise rejection, the controller being programmed to: use the first input transducer and the second input transducer to generate an interference signal and a target signal from a sound from surroundings, the interference signal and/or the target signal being referenced to a useful signal source disposed in a target direction; generate the target signal with a target directivity pattern that has a homogeneous or substantially homogeneous characteristic over a half-space opposite the target direction; compare, for each of at least one first plurality of frequency bands, an acoustic characteristic of the target signal with a corresponding acoustic characteristic of the interference signal, and a comparison is used to ascertain a provisional weighting factor, a range of values of which containing at least three values (80a, 80b, 80c), the provisional weighting factor being used to form for a frequency band a weighting factor for a respective frequency band in each particular case; and weight an input signal to be processed for the hearing system on a frequency-band-by-frequency-band basis using the respective weighting factor resulting in a weighted input signal, and the weighted input signal to be processed is used to generate an output signal.

18. The hearing system according to claim 17, wherein said hearing apparatus is a hearing device.

19. The hearing system according to claim 18, wherein: said hearing device has a housing in which said first input transducer and said second input transducer are disposed; said hearing device has an earpiece in which a further input transducer for generating the input signal to be processed is disposed; and said controller is set up to use signals from said first input transducer and said second input transducer to form the interference signal and the target signal.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1A is a diagrammatic, side view of a hearing device with a housing and an earpiece, two input transducers being arranged in the housing and one being arranged in the earpiece;

(2) FIG. 1B is a side view showing the hearing device according to FIG. 1A, only one input transducer being arranged in the housing;

(3) FIG. 2 is a block diagram of noise rejection in the hearing device according to FIG. 1A by means of weighting factors that are determined by means of directional microphones;

(4) FIG. 3 is an illustration showing a directional dependency of provisional weighting factors in the hearing device according to FIG. 2;

(5) FIG. 4 is an illustration showing a hearing system with a hearing device and a cell phone; and

(6) FIG. 5 is a block diagram showing an alternative noise rejection to that in FIG. 2 in the hearing device according to FIG. 1A.

DETAILED DESCRIPTION OF THE INVENTION

(7) Mutually corresponding parts and magnitudes are provided with the same reference signs in each particular case throughout the figures.

(8) Referring now to the figures of the drawings in detail and first, particularly to FIG. 1A thereof, there is shown a side view of a hearing system 2 formed by a hearing apparatus 1. In this instance, the hearing apparatus 1 in the present case is embodied by a hearing device 4. The hearing device 4 has a housing 6, and an earpiece 8 connected to the housing 6. In the present case, the hearing device 4 is configured as an RIC device that has an output transducer 10 in the form of a loudspeaker at the end of the earpiece 8. A connection 12 mechanically connects the earpiece 8 to the housing 6; in this instance, a signal connection 14 that electronically connects the output transducer 10 to a signal processing device 16 in the housing 6 (dashed line) in a manner yet to be described also runs along the connection 12. The signal processing device 16 in this instance forms a control device 18 for the hearing system 2 and is in particular embodied by one or more signal processors that each have an assigned main memory. A first input transducer 21 and a second input transducer 22 are arranged at a slight distance from one another in the housing 6 and are each electronically connected to the control device 18 (dashed line).

(9) During the operation of the hearing device 4, the first and second input transducers 21, 22 each generate input signals (not depicted in more detail) and output them to the signal processing device 16, where they are processed, and in particular amplified on a frequency-dependent basis and possibly compressed, on the basis of the individual audiological stipulations and requirements of a wearer of the hearing device 4. The signal processing device 16 uses the signal connection 14 to accordingly output an output signal (not depicted in more detail) to the output transducer 10, which converts the output signal into an output sound (not depicted in more detail) that is supplied to the ear of the wearer. Owing to the physical distance between the first and second input transducers 21, 22, spatial processing in the signal processing device 16 by means of directional microphones is also possible for the purpose of generating said output signal. As a result, it is possible to use the directional microphones to specifically emphasize a useful signal in the surroundings of the wearer, usually embodied by words of an interlocutor of the wearer, or to specifically cut ambient noise and/or other sound sources away from the useful signal source by means of directional microphones.

(10) During this directionally sensitive signal processing, important information for spatial hearing can be lost for the wearer, however. The present hearing device 4 is therefore set up to use the signals from the first and second input transducers 21, 22 in a manner yet to be described to ascertain frequency-dependent weighting factors by means of which an a priori preferably omnidirectional input signal to be processed is weighted in the signal processing device 16, the weighting factors being supposed to bring about advantageous noise rejection across individual frequency bands. An input signal to be processed that can be used in this instance is in particular the signal 24 generated by the first input transducer 21.

(11) Alternatively, the hearing device 4 can also have a further input transducer 26 in the earpiece 8, and the input signal to be processed can then be embodied by the signal from said further input transducer 26. In the present case, this has the advantage that when the hearing device 4 is worn as intended, wherein at least part of the housing 6 is worn by the wearer behind the auricle of one of his ears, and the earpiece 8 is inserted with the end of the output transducer 10 into the entrance to the associated ear canal, the further input transducer 26 is arranged in the region of the entrance to the ear canal, and therefore the signal generated by the further input transducer 26 has substantially the same behavior in respect of a shadowing effect of the head and in particular the auricle of the wearer as sound that reaches the ear of the wearer without the presence of the hearing device 4.

(12) FIG. 1B schematically depicts a side view of an alternative configuration of the hearing apparatus 1 shown in FIG. 1A. In FIG. 1B too, the hearing apparatus 1 is embodied by a hearing device 4 in the form of an RIC device with a housing 6, part of which should be worn behind the auricle during operation, and an earpiece 8, wherein the housing 6 has a first input transducer 21 arranged in it that is signal-connected to a control device 18 that is likewise arranged in the housing 6. An output transducer 10 is arranged in the earpiece 8 and connected to the control device 18 by way of a signal connection 14, the signal connection 14 running along the mechanical connection 12 between the housing 6 and the earpiece 8. The earpiece 8 has the free end inserted into the entrance to the ear canal of the wearer for operation of the hearing device 4.

(13) A second input transducer 22 is arranged in the earpiece 8. The signal from the first and second input transducers 21, 22 are used, analogously to the hearing device 4 according to the FIG. 1A, in a manner yet to be described to ascertain frequency-dependent weighting factors by means of which the input signal to be processed, which is generated by the second input transducer 22 in the present example, is weighted in the control device 18 for the purpose of noise rejection. A significant difference here as compared with the hearing device 4 depicted in FIG. 1A is therefore that the second input transducer 22, the signal from which is used to determine the frequency-dependent weighting factors, is arranged in the earpiece 8 (and not, like the first input transducer 21, in the housing 6).

(14) The hearing device 4 according to FIG. 1A or according to FIG. 1B can in particular also be in the form of 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 according to FIG. 1A) is arranged in or on the earpiece 8 (the free end of which is formed by e.g. a dome or an earmold in the case of a BTE device), then the signal connection 14 to the control device 18 in the housing 6 runs along the sound tube, preferably in a dedicated cable. In particular, a signal processing device 16 as a part of the control device 18 can also be arranged in the earpiece 8. If the earpiece 8 has an input transducer, then the hearing device 4 can in particular be embodied by a type of combination of a BTE or RIC device with an ITE or CIC device.

(15) FIG. 2 uses a block diagram to schematically depict the hearing system 1, formed by the hearing device 4, according to FIG. 1A with the already outlined signal processing for noise rejection. The hearing device 4 comprises the first input transducer 21 and the second input transducer 22, which is arranged at a distance D from the first input transducer. The first input transducer 21 generates a first signal 31 and the second input transducer 21 generates a second signal 32 from ambient sound, which is not depicted in more detail. Possible pre-amplification and preprocessing such as for example wideband compression and A/D conversion are already supposed to be included in the function of the first and second input transducers 21, 22 in this case.

(16) The first and second signals 31, 32 are now each transformed to the time/frequency domain in filter banks 33, 34. The thus filtered first signal 31 is now delayed by a time constant T on a frequency-band-by-frequency-band basis in each particular case, possibly also filtered using a complex transfer function (not depicted), which can possibly take into consideration level and/or phase differences of the two input transducers 21, 22, and subtracted from the filtered signal 32, and subsequently filtered using a low-pass filter 35. The low-pass filtering is effected because the subtraction attenuates low-frequency signal components, since the time constant T, as the acoustic time of flight between the two input transducers 21, 22 owing to the distance D, leads to low-frequency signal components in both input transducers 21, 22 still having similar amplitudes despite the propagation.

(17) The low-pass filtering now results in an interference signal 36 that, owing to the time delay T before the subtraction of the two input signals 31, 32, which corresponds exactly to the acoustic time of flight for the distance D, has, in each frequency band, a substantially anticardioid directivity pattern 64, the maximum attenuation of which points in a target direction 38 embodied by a connecting line from the second input transducer 22 to the first input transducer 21 and coincides with the front direction when the hearing device 4 is worn as intended.

(18) The second signal 32 broken down into individual frequency bands by the filter bank 34 has, as microphone signal, a substantially omnidirectional directivity pattern 63 for each frequency band. This second signal 32 is now used as target signal 40. From the target signal 40 and from the interference signal 36 in each frequency band, an acoustic characteristic 42 is now ascertained in each particular case, the acoustic characteristic being supposed to provide information about the energy content of the relevant signal in the respective frequency band in each particular case. This is ensured in the present case by virtue of the acoustic characteristic 42 chosen being the absolute value of the respective signal. In particular, a signal power or a signal level or a monotonous, e.g. quadratic or logarithmic, function of the signal power, of the absolute value or of the signal level can also be used as characteristic 42, however. From the absolute value 44 of the interference signal 36 and from the absolute value 46 of the target signal 40, temporal averages 48 and 49 are now formed in each particular case for smoothing purposes. Subsequently, a quotient 50 of the temporal average 49 of the absolute value 46 of the target signal 40 as numerator and the temporal average 48 of the absolute value 44 of the interference signal 36 as denominator is formed. This quotient, which may also be able to be limited to an upper limit value of for example 6 dB or higher (e.g. 12 dB or 15 dB), forms a provisional weighting factor 51 for the respective frequency band.

(19) A maximum 52 of the provisional weighting factors 51 is now determined over all frequency bands and stipulated as normalization factor 52. The provisional weighting factors 51 are normalized using the normalization factor 52 ascertained in this manner, as a result of which a weighting factor 54 is obtained for each frequency band.

(20) The further input transducer 26 is used to generate an input signal 56 to be processed. The input signal 56 to be processed is transformed to the time-frequency domain by a filter bank 57. The filter banks 33, 34, 57 preferably have an identical frequency resolution and identical edge gradient.

(21) The weighting factor 54 is now applied by multiplication to the thus transformed input signal 56 to be processed. The frequency-band-by-frequency-band signal components of the input signal 56 to be processed that are weighted as described are used to generate, for example by means of inverse fast Fourier transformation, a wideband output signal 58 that is converted into an output sound 60 by the output transducer 10. Before the output signal 58 is generated, additional signal processing, not depicted in more detail, can in particular also take place, which can comprise for example a frequency-band-by-frequency-band cut or boost for the signal components on the basis of the individual audiological requirements of the wearer, and/or additional measures for rejecting disturbing noise, and/or acoustic feedback. In particular, to apply the weighting factor 54 to the input signal 56 to be processed in the respective frequency band, an absolute value and a phase can first be ascertained from the input signal 56 to be processed, the weighting factor 54 being applied only to the absolute value, and the phase being used for a back-transformation to generate the output signal 58.

(22) In order to apply the noise rejection depicted on the basis of FIG. 2 to the hearing device 4 according to FIG. 1B, the input signal 56 to be processed is generated by the first or the second input transducer 21 or 22. The directional signal 56 to be processed therefore corresponds to the first or second signal 31 or 32. In general, further alternative configurations of the hearing device 4 are also conceivable for the noise rejection, for example a so-called ITE hearing device having two input transducers arranged in the region of the ear canal as first and second input transducers 21, 22 for generating the two signals 31, 32 and the input signal 56 to be processed.

(23) FIG. 3 uses a plan view to schematically show the effect of the provisional weighting factor 51 according to FIG. 2 in respect of sound signals from different spatial directions in a simplified manner. The left-hand image shows a wearer 62 of the hearing device 4 and the omnidirectional directivity pattern 63 of the target signal 40, the directivity pattern surrounding him. The middle image depicts the same wearer 62 again, this time with the anticardioid directivity pattern 64 of the interference signal 36, which directivity pattern has its maximum attenuation in the target direction 38. It can immediately be seen that no significant attenuation takes place for a sound signal from the half-space 66 opposite the target direction 65 as a result of the interference signal 36, since the anticardioid directivity pattern 64 has a substantially homogeneous characteristic there in a similar manner to the omnidirectional directivity pattern 63.

(24) The right-hand image depicts the directional dependency 68 of the provisional weighting factor 51, as can be imagined schematically from the two directivity patterns 63, 64. Whereas the target signal 40 and the interference signal 36 have a largely similar sensitivity toward sound signals in the rear half-space 66, the provisional weighting factor 51 has a substantially homogeneous and therefore directionally independent characteristic in this region. Only as the target direction 38 is approached to an increasing extent do the differences in the two directivity patterns 63, 64 become increasingly noticeable, which means that the provisional weighting factor 51 has a severe bulge in the target direction 38. This bulge can be limited to a finite value in this case in particular by means of compression or limiting.

(25) Owing to the considerable boost in the target direction 38, the approach outlined with reference to FIG. 2 can now involve the normalization using the maximum 52 of all provisional weighting factors 51 being used to achieve the effect that the weighting factor 54 is currently 1 only in that frequency band in which the maximum spectral proportion of useful signal from the target direction 38 is present. Owing to the division of the provisional weighting factors 51 by the normalization factor 52, the weighting factor 54 results in a cut being effected for other frequency bands that ends up being all the greater the smaller the spectral proportion of useful signal from the target direction 38 in the respective frequency band.

(26) FIG. 4 uses a plan view to schematically depict an alternative configuration of the hearing system 2 with respect to the variants shown in FIGS. 1A and 1B, which comprises a hearing apparatus 1 and an external device 70. The external device 70 is embodied by a cell phone 71. The hearing apparatus 1 is embodied by a hearing device 4 that is worn by the wearer 62 on one ear (not depicted in more detail). The hearing device 4 has at least one first input transducer 21 and can be configured as an ITE device, for example. The cell phone 71 is positioned directly in front of an interlocutor 74 of the wearer 62 such that a microphone of the cell phone, as second input transducer 22 of the hearing system 1, can record words 75 of the interlocutor 74 without hindrance and particularly clearly.

(27) So as now to be better able to reject noise, e.g. in the form of disturbing noise from the directional sources of interference 76, 78, which in their nature are not specified in more detail, or diffuse background noise (not depicted in more detail), by means of the hearing device 4, the signals from the first input transducer 21 arranged in the hearing device 4 and from the second input transducer 22 arranged in the cell phone 71 are used in a manner yet to be described to generate frequency-dependent weighting factors that are applied to the signal from the first input transducer 21 in the hearing device 4. The weighting factors are generated such that spectral components of the sources of interference 76, 78 (or diffuse background noise) in the signal from the first input transducer 21, which ultimately represents the overall sound occurring there, are preferably cut by the weighting that takes place. Furthermore, spectral components of the words 35 are preferably supposed to be retained by the weighting and in particular boosted relative to the disturbing noise from the sources of interference 76, 78.

(28) This is done by virtue of the weight factors being obtained on a frequency-band-by-frequency-band basis using a target signal and an interference signal, the target signal being supposed to contain as high a relative proportion of the useful signal (referenced e.g. to the total energy in a frequency band), that is to say of the words 75 in the present case, as possible and the interference signal being supposed to contain as low a relative proportion of the useful signal as possible. Similarly, a level of rejection of the sources of interference 76, 78 should preferably not be dependent on the direction thereof, but rather should preferably be dependent merely on the volume thereof. This stipulation is achieved by virtue of the interference signal used being the signal from the first input transducer 21 and the target signal used being the signal from the second input transducer 22. The signal from the second input transducer 22 has a particularly high proportion of words 75 of the interlocutor 74 owing to the positioning of the cell phone 71, whereas, solely on account of the physical distance of the wearer 62 from the interlocutor 74, the first input transducer 21 in the hearing device 4 will pick up a lower proportion of words 75, and therefore higher spectral proportions of the sources of interference 76, 78 are recorded in the signal from the first input transducer.

(29) In particular, the hearing system 2 can also be configured as a binaural hearing device system that, in addition to the hearing device 4, has a further hearing device (not depicted) with the second input transducer, which the wearer 62 should wear on the other ear. Provisional weighting factors 51 can first of all be determined in this further hearing device in a similar manner to in the hearing device 4, as already described (cf. FIG. 2). These provisional weighting factors, which are then contralateral with reference to the hearing device 4, are transmitted to the hearing device 4, where the weighting factors to be applied locally in the hearing device 4 for the individual frequency bands can firstly be generated on the basis of a comparison of the local provisional weighting factors with the contralateral provisional weighting factors.

(30) Secondly, the contralateral provisional weighting factors can also be used for the purposes of binaural signal processing if for example a signal to be processed is additionally also transmitted from the (contralateral) further hearing device to the hearing device 4. Weighting factors that are to be applied to the contralateral signal from the further hearing device in the hearing device 4 for the purposes of binaural signal processing are then formed using the contralateral provisional weighting factors.

(31) FIG. 5 uses a block diagram to schematically depict an alternative to the noise rejection according to FIG. 2 for the hearing device 4 shown therein. Up to the formation of the quotient 50 of the absolute value 46 of the useful signal 40 as numerator and the absolute value 44 of the interference signal 36 as denominator, the signal processing in this case can proceed substantially identically (the low-pass filter 35 for the interference signal 36 has not been shown for the sake of simplicity), the input signal 56 to be processed additionally being embodied in the present case by the second signal 32 in the time-frequency domain (and therefore that is to say the useful signal 40). Similarly, the signal to be processed that is used could also be the first signal 31 (in the time-frequency domain) or the signal from a further input transducer 26 (which is not provided in the exemplary embodiment according to FIG. 5), however.

(32) In contrast to the exemplary embodiment depicted with reference to FIG. 2, the weighting factor 54 can now also be produced in the individual frequency bands by virtue of the quotient 50 being mapped in each particular case to a discrete range of values 80 comprising e.g. three values 80a, 80b, 80c for the provisional weighting factor 51. By way of example, an upper, a middle and a lower interval 82a, 82b, 82c are stipulated for the quotient 50, these being mapped to the largest value 80a (e.g. 1 or 1.3 or a value in between) or the middle value 80b (e.g. 0.75 or the like) or the smallest value 80c (e.g. 0.5 or less) for the provisional weighting factor 51 in each particular case. The provisional weighting factor 51 thus produced can moreover also be temporally smoothed. Normalization (not depicted) is also possible (in particular if the largest value stipulated in the discrete range of values is a value #1).

(33) In a similar manner (not depicted), the acoustic characteristic 42 of the target signal 40, that is to say the absolute value 46 of said acoustic characteristic in the present example, and the corresponding acoustic characteristic 42 of the interference signal 36, that is to say the absolute value 44 of the acoustic characteristic in the present case, 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 provisional weighting factor 51 assigned is the largest value 80a in the predefined, discrete range of values 80. If, however, the absolute value 44 of the interference signal 36 is greater, then the absolute value 46 of the target signal 40 is scaled by a factor >1 (e.g. 1.1 or 1.2), and again compared with the absolute value 44 of the interference signal 36. If the absolute value 46 of the target signal 40 is now greater, the provisional weighting factor 51 assigned is the middle value 80b in the discrete range of values 80, otherwise the smallest value 80c. Although the, cascaded, greater-than-less-than comparisons with interim scaling can likewise be mathematically formulated as the above-described mapping of the quotient 50 to the discrete range of values 80 for the provisional weighting factor 51, in practice they are sometimes easier to implement e.g. on hardwired circuits.

(34) Although the invention has been illustrated and described more thoroughly in detail by the preferred exemplary embodiment, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by a person skilled in the art without departing from the scope of protection of the invention.

(35) The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: 1 hearing apparatus 2 hearing system 4 hearing device 6 housing 8 earpiece 10 output transducer 12 connection 14 signal connection 16 signal processing device 18 control device 21 first input transducer 22 second input transducer 24 input signal 26 further input transducer 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 characteristic 44 absolute value of the interference signal 46 absolute value of the target signal 48 temporal average 49 temporal average 50 quotient 51 provisional 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 wearer 63 omnidirectional directivity pattern 64 anticardioid directivity pattern 66 half-space 68 directional dependency 70 external device 71 cell phone 74 interlocutor 75 words 76 source of interference 78 source of interference 80 discrete range of values 80a largest value 80b middle value 80c smallest value 82a upper interval 82b middle interval 82c lower interval