METHOD FOR FITTING A DIGITAL HEARING AID, HEARING AID AND COMPUTER PROGRAM PRODUCT

Abstract

A method fits a digital hearing aid having an input transducer, a signal processing device and an output transducer. The signal processing device is configured to form an evaluation unit, a comparator unit, and a pre-amplification unit. An acoustic test signal is generated by an external testing device while the hearing aid is worn by a hearing-aid wearer. A digital test input signal is generated by the input transducer on the basis of the acoustic test signal. A sound pressure-dependent test quantity is determined on the basis of the digital test input signal by the evaluation unit. A deviation between the sound pressure-dependent test quantity and a reference quantity stored in the signal processing device is determined by the comparator unit. A pre-amplification by the pre-amplification unit is adjusted on the basis of the determined deviation.

Claims

1. A method for fitting a digital hearing aid having an input transducer, a signal processing device and an output transducer, the signal processing device having an evaluation unit, a comparator unit, and a pre-amplification unit, which comprises the steps of: generating an acoustic test signal by means of an external testing device while the digital hearing aid is worn by a hearing-aid wearer; generating a digital test input signal by means of the input transducer on a basis of the acoustic test signal; determining a sound pressure-dependent test quantity on a basis of the digital test input signal by means of the evaluation unit; determining a deviation between the sound pressure-dependent test quantity and a reference quantity stored in the signal processing device by means of the comparator unit; and adjusting a pre-amplification by the pre-amplification unit on a basis of the deviation determined.

2. The method according to claim 1, which further comprises: using a specified digital test signal to generate an acoustic reference signal by means of an external reference testing device while the hearing aid is held by a test holder; generating a digital reference input signal by means of the input transducer on a basis of the acoustic reference signal; determining the reference quantity on a basis of the digital reference input signal by means of the evaluation unit; and storing the reference quantity in the signal processing device.

3. The method according to claim 2, which further comprises using the specified digital test signal to generate the acoustic test signal by means of the external testing device.

4. The method according to claim 1, wherein the pre-amplification unit is disposed upstream of the evaluation unit.

5. The method according to claim 1, wherein the signal processing device is configured to form a main amplification unit which is disposed downstream of the pre-amplification unit.

6. The method according to claim 5, wherein a main amplification by the main amplification unit is adjusted after the pre-amplification has been adjusted.

7. The method according to claim 6, which further comprises adjusting the main amplification on a basis of a hearing deficit of the hearing-aid wearer.

8. The method according to claim 5, wherein the main amplification unit is disposed downstream of the evaluation unit.

9. The method according to claim 1, which further comprises storing the sound pressure-dependent test quantity in the signal processing device.

10. The method according to claim 2, which further comprises: linking the reference quantity to an identification feature which assigns the reference quantity to an underlying said digital test input signal; and storing the reference quantity with its associated said identification feature in the signal processing device.

11. The method according to claim 10, which further comprises: determining a test feature on a basis of the digital test input signal by means of the evaluation unit; and determining the deviation between the test quantity and the reference quantity only if the identification feature is determined as the test feature.

12. The method according to claim 2, which further comprises: using a plurality of specified digital test signals in succession to respectively generate the acoustic reference signal by means of the external reference testing device while the hearing aid is held by the test holder; generating the digital reference input signal by means of the input transducer on a basis of the acoustic reference signal; determining the reference quantity on a basis of the digital reference input signal by means of the evaluation unit; linking each said reference quantity to an identification feature which assigns the reference quantity to a respective underlying digital test signal; and storing reference quanitites with associated identification features in the signal processing device.

13. The method according to claim 12, wherein selecting a digital test signal from the specified digital test signals; using the digital test signal selected to generate the acoustic test signal by means of the external testing device; generating the digital test input signal by means of the input transducer on a basis of the digital test signal; determining the sound pressure-dependent test quantity on a basis of the test input signal by means of the evaluation unit; determining a test feature on a basis of the test input signal by means of the evaluation unit; comparing the test feature to identification features stored by means of the comparator unit and the identification feature corresponding to the test feature is determined; determining a deviation between the test quantity and the reference quantity linked to the identification feature determined by means of the comparator unit; and adjusting the pre-amplification by the pre-amplification unit on a basis of the deviation.

14. A hearing aid configured to carry out at least one method step of the method according to claim 1 in at least one mode of operation.

15. A non-transitory computer program product containing a program executable on a data processing unit, the program automatically carrying out at least one method step of the method according to claim 1 after being started.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0052] FIG. 1 is a block diagram of a digital hearing aid in an external reference testing device according to the invention;

[0053] FIG. 2 is a block diagram of the digital hearing aid in the external testing device; and

[0054] FIG. 3 is a graph showing two gain curves.

DETAILED DESCRIPTION OF THE INVENTION

[0055] Parts corresponding to one another are in each case provided with the same reference signs in all figures.

[0056] Referring now to the figures of the drawings in detail and first, particularly to FIG. 1 thereof, there is shown a hearing aid 2 described below in exemplary fashion. It is in the form of a digital hearing aid 2 and contains an input transducer 4, a signal processing device 6 and an output transducer 8.

[0057] The input transducer 4 serves to generate digital input signals on the basis of acoustic input signals which are incident on the hearing aid 2 on the input side. To this end, the input transducer 4 has a microphone 10 and an analog-to-digital converter 12 in the exemplary embodiment. The corresponding digital input signals are processed in the signal processing device 6, with digital output signals being generated on the basis of the digital input signals. Acoustic output signals are generated by the output transducer 8 on the basis of the digital output signals and are output by the hearing aid 2 on the output side. In this case, the output transducer 8 according to FIG. 1 contains a digital-to-analog converter 14 and a loudspeaker 16.

[0058] The signal processing device 6 is furthermore configured to form a plurality of data processing modules or software program modules, specifically an evaluation unit 18, a comparator unit 20, a pre-amplification unit 22 and a main amplification unit 24. Moreover, the signal processing device 6 contains a permanent memory 26.

[0059] The method described in exemplary fashion below is used for fitting the hearing aid 2, the method containing at least three parts, specifically a pre-fitting session, a first fitting session part and a second fitting session part.

[0060] Of these three parts, the pre-fitting session is carried out first in time. It is preferably carried out at the manufacturer of the hearing aid 2. a reference testing device 28 with a loudspeaker 30 and a test holder 32 is used for the pre-fitting session. In this case, the test holder 32 is formed by an artificial head, for example. The hearing aid 2 is held by the test holder 32 during the pre-fitting session, as indicated in FIG. 1.

[0061] A specified digital signal is used during the pre-fitting session in order to generate an acoustic reference signal by means of the loudspeaker 30 of the reference testing device 28. Subsequently, a digital reference input signal, that is to say a digital input signal on the basis of the acoustic reference signal, then is generated by means of the input transducer 4 on the basis of the acoustic reference signal. Moreover, a reference quantity is determined on the basis of the digital reference input signal by means of the evaluation unit 18 of the signal processing device 6, and this reference quantity then is stored in the permanent memory 26 of the signal processing device 6.

[0062] The digital test signal, which is for example present as a file, preferably is a noise signal and in particular a noise signal with the given sound pressure level value of 65 dB, for example. By reproducing the digital test signal by means of the loudspeaker 30 of the reference testing device 28, noise is then generated as an acoustic reference signal, the noise being based on the digital test signal and being influenced by the reference testing device 28.

[0063] In the exemplary embodiment, the sound pressure level value of the noise now is determined as a reference quantity within the scope of the pre-fitting session by the evaluation unit 18 of the signal processing device 6, with the sound pressure level value determined during the pre-fitting session being influenced by the reference testing device 28, that is to say the loudspeaker 30, the test holder 32 and the remaining surroundings of the hearing aid 2, and by the components of the hearing aid 2, for example the microphone 10.

[0064] The two other specified parts of the method, that is to say the first fitting session part and the second fitting session part, are carried out at a service provider, for example an audiologist, in the exemplary embodiment. In this case, the first fitting session part is carried out first, followed by the second fitting session part. A testing device 34 with a loudspeaker 36 is used at least for the first fitting session part, and the hearing aid 2 is worn by a hearing-aid wearer 38 during the first fitting session part.

[0065] The digital test signal is used while carrying out the first fitting session part to generate an acoustic test signal with the aid of the loudspeaker 36 of the testing device 34. Then, a digital test input signal, that is to say a digital input signal that depends on the acoustic test signal, is generated on the basis of the acoustic test signal by means of the input transducer 4 of the hearing aid 2. Further, a sound pressure-dependent test quantity is determined on the basis of the digital test input signal by means of the evaluation unit 18 of the signal processing device 6. This sound pressure-dependent test quantity is then compared to the reference quantity stored in the permanent memory 26 of the signal processing device 4 by means of the comparator unit 20 and a deviation is determined between the sound pressure-dependent test quantity and the reference quantity. Then, a pre-amplification is adjusted by the pre-amplification unit 22 on the basis of the determined deviation.

[0066] By reproducing the digital test signal by means of the loudspeaker 36 of the testing device 34, noise is generated as an acoustic test signal, the noise being based on the digital test signal and being influenced by the testing device 34. The sound pressure level value of the noise is then determined in the exemplary embodiment as a sound pressure-dependent test quantity within the scope of the first fitting session part by the evaluation unit 18 of the signal processing device 6, with the sound pressure level value determined during the first fitting session part being influenced by the testing device 34, that is to say the loudspeaker 36 in particular, by the remaining surroundings of the hearing aid 2, that is to say also by the hearing-aid wearer 38, and by the components of the hearing aid 2, for example the microphone 10.

[0067] Therefore, the evaluation unit 18 of the signal processing device 6 typically determines two different sound pressure level values during the pre-fitting session and during the first fitting session part, despite the same digital test signal. These two sound pressure level values are compared to one another and a type of com-pensation is preferably carried out by adjusting the pre-amplification by the pre-amplification unit 22 of the signal processing device 6. In this context, the pre-amplification by the pre-amplification unit 22 is preferably adjusted in such a way at the sound pressure level value determined during the first fitting session part is changed toward the sound pressure level value determined during the pre-fitting session.

[0068] The pre-amplification is an additional amplification in addition to the main amplification by the main amplification unit 24. In the exemplary embodiment, the pre-amplification is adjusted independently of a hearing deficit of the hearing-aid wearer 38.

[0069] In contrast to the pre-amplification, the main amplification by the main amplification unit 24 is adapted to the hearing deficit of the hearing-aid wearer 38. This is implemented in the second fitting session part which follows the completion of the first fitting session part.

[0070] It is further expedient for the digital hearing aid 2 to be in the form of a multichannel hearing aid. Then, 4 to 10 channels are preferably realized in this case. In the case of such an embodiment of the hearing aid 2, the signal processing device 6 for example initially implements a channel-dependent and hence frequency-dependent separation or split of a digital input signal into a plurality of partial signals. In this case, each partial signal reproduces a frequency range of the digital input signal assigned to a channel. The resultant partial signals are then further preferably processed further independently of one another in the individual channels and are combined at the end to form a digital output signal.

[0071] Then, an above-described signal processing is realized for each channel in an advantageous development by means of an evaluation unit 18, a comparator unit 20, a pre-amplification unit 22 and a main amplification unit 24. That is to say, the data processing modules shown in the signal processing device 6 in FIGS. 1 and 2 are then realized for each channel.

[0072] Independently thereof, the pre-amplification unit 22 is preferably upstream of the evaluation unit 18 from a signal processing point of view. That is to say that, in the sequence of the signal processing in the signal processing device 6, i.e., in the sequence of the individual process steps or the method steps of the signal processing, the pre-amplification unit 22 is applied first and the evaluation unit 18 is only applied during the further course of the signal processing. Further, the main amplification unit 22 is preferably downstream of the evaluation unit 18 from a signal processing point of view.

[0073] In most cases, the signal processing device 6 is furthermore configured to form an additional data processing module, specifically a module for noise suppression 40. In this case, noise suppression 40 is preferably disposed downstream of the main amplification unit 22 from a signal processing point of view.

[0074] The main concept of the invention will subsequently still be explained on the basis of a schematic diagram, which is reproduced in FIG. 3.

[0075] In this case, the sound pressure level LO at the output of a digital hearing aid, referred to as output level for short, is depicted as a function of the sound pressure level LI at the input of the hearing aid, referred to as input level for short. In this case, the curve depicted in exemplary fashion with a solid line shows two so-called knee points at 50 dB and at 65 dB.

[0076] A simplified case is considered here for reasons of clarity, within the scope of which case input-side effects, for example a shadowing of the hearing-aid microphones, cause the sound pressure level LI registered by the hearing aid, that is to say in particular the sound pressure level LI registered under routine conditions (hearing aid is worn by the hearing aid wearer), to be reduced by a value of 7 dB in comparison with the case of the original reception, that is to say under laboratory conditions in particular (hearing aid is affixed to an artificial head). Moreover, only the difference at two different input levels is considered below.

[0077] Thus, the solid line now shows the output level of the hearing aid as a function of the input level. The hearing aid operates compressively, that is to say there are certain points, in this case the two aforementioned knee points, from where the output level increases more slowly than the input level. As a rule, the knee points are set such that a desired output level is obtained for a certain input signal, for example a speech-simulating noise at low and mid input levels.

[0078] In the case considered here, the level registered by the hearing aid as a result of input-side shadowing, that is to say under routine conditions in particular, now is 7 dB lower than expected. In FIG. 3, four level values are marked in exemplary fashion by dashed lines, specifically two expected level values LI,E1 and LI,E2 and two associated actually registered level values LI,A1 and LI,A2. In both cases, the actually registered level value is below the expected level value by 7 dB on account of the input-side shadowing.

[0079] This leads to the output level of the hearing aid deviating from the intended value or target value. However, this deviation DL is not constant as a result of the compressive behavior of the hearing aid. While it exactly corresponds to the difference of the input in terms of magnitude for low input levels, that is to say 7 dB in the comparison of LI,A1 with LI,E1, it is significantly lower at mid input levels, specifically 2.8 dB in the comparison of LI,A2 with LI,E2. This also illustrates the fundamental problem of such input-side effects.

[0080] If only a single measurement is then carried out at one test level, it is not possible to register the level dependency in its entirety. This is because if a measurement is carried out at a low input level, it is determined that the output level of the hear-ing aid is 7 dB too low. If the deviation is not compensated on the input side, as per the invention, but on the output side as per the prior art, that is to say by means of the standard amplification level, i.e., linearly, this leads to overcompen-sation at mid input levels. Such an output-side compensation according to the prior art in principle shifts the curve in FIG. 3 to the dashed line. In the example, the output level of the hearing aid at mid levels, that is to say in the comparison of LI,A2 with LI,E2, would be 4.2 dB too high.

[0081] Thus, conventionally, the output level of the hearing aid would have to be measured at a plurality of input levels and the knee points would be displaced as a correction. However, this has several disadvantages. Among others, the measuring outlay is relatively high. Further, the repetition accuracy of the measurement is low, in particular at low input levels. Moreover, a measurement at high input levels is required as a matter of principle, which is uncomfortable for the hearing-aid wearer. However, what is of particular importance is that a shift of the knee points only corrects the output level of the hearing aid. Many adaptive algorithms, for example the noise estimation or the control of directionality, are not corrected by this measure.

[0082] By contrast, an additional (pre-)amplification stage before the (main) amplification stage with compressive behavior brings about a complete compensation of the input-side effect. An increase of the (pre-)amplification of 7 dB in this case caus-es the actually registered level values, that is to say also LI,A1 and LI,A2, to be shifted to the expected level values, that is to say LI,E1 and LI,E2, respectively, and the hearing aid operates completely correctly in relation to the output level, but in par-ticular also in relation to adaptive, level-dependent signal processing algorithms.

[0083] In principle, all that is still required in that case is a single measurement at a test signal level, which firstly has a sufficient signal-to-noise ratio and secondly is not uncomfortably loud. During this measurement, the input of the hearing aid is measured and optionally corrected in the described method. The measurement of the output of the hearing aid can then be corrected by a linear amplification of the second amplification stage.

[0084] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0085] 2 Hearing aid [0086] 4 Input transducer [0087] 6 Signal processing apparatus [0088] 8 Output transducer [0089] 10 Microphone [0090] 12 Analog-to-digital converter [0091] 14 Digital-to-analog converter [0092] 16 Loudspeaker [0093] 18 Evaluation unit [0094] 20 Comparator unit [0095] 22 Pre-amplification unit [0096] 24 Main amplification unit [0097] 26 Permanent memory [0098] 28 Reference testing device [0099] 30 Loudspeaker [0100] 32 Test holder [0101] 34 Testing device [0102] 36 Loudspeaker [0103] 38 Hearing-aid wearer [0104] 40 Noise suppression [0105] LO Output level [0106] LI Input level [0107] LI,E1 Expected level value 1 [0108] LI,E2 Expected level value 2 [0109] LI,A1 Registered level value 1 [0110] LI,A2 Registered level value 2