SOUND ENRICHMENT FOR THE RELIEF OF TINNITUS

Abstract

A sound enrichment system for provision of tinnitus relief, the sound enrichment system includes a noise generator, at least one signal modulator for random or pseudo-random modulation of a noise signal that is obtained using the noise generator, and an output transducer for conversion of the modulated noise signal to an acoustic signal for presentation to a user. A method of providing a noise enriched sound signal for provision of relief of tinnitus includes generating a randomly or pseudo-randomly modulated noise signal, generating an acoustic noise signal using the modulated noise signal, and presenting the acoustic noise signal to a tinnitus suffering person.

Claims

1-20. (canceled)

21. A sound enrichment system for tinnitus relief, comprising: at least one sound input configured to receive at least one sound signal; an environment classifier configured to generate an environmental classification of the at least one sound signal; a noise generator configured to generate a noise signal; at least one signal modulator configured to modulate the noise signal to generate a modulated noise signal based on the environmental classification; and an output configured to convert the modulated noise signal for presentation to a user.

22. The sound enrichment system of claim 21, further comprising: a hearing block configured to convert the at least one sound signal into a first output signal, wherein the output is configured to convert one or both of the first output signal and the modulated noise signal for presentation to the user.

23. The sound enrichment system of claim 22, wherein the hearing block is a hearing compensation block, and wherein the first output signal is configured for compensation of a hearing loss of the user.

24. The sound enrichment system of claim 21, wherein to generate the modulated noise signal based on the environmental classification, the at least one signal modulator is configured to: initiate generation of the modulated noise signal based on the environmental classification of an ambient sound environment of the sound enrichment system.

25. The sound enrichment system of claim 21, wherein to generate the modulated noise signal based on the environmental classification, the at least one signal modulator is configured to: modulate a noise signal based on the environmental classification.

26. The sound enrichment system of claim 21, wherein to generate the modulated noise signal based on the environmental classification, the at least one signal modulator is configured to: determine a type of noise present in the at least one sound signal; and modulate a noise signal based on the type of noise present in the at least one sound signal.

27. The sound enrichment system of claim 21, wherein to generate the modulated noise signal based on the environmental classification, the at least one signal modulator is configured to: determine whether or not speech is present in the at least one sound signal; and modulate a noise signal based at least in part on whether or not speech is present in the at least one sound signal.

28. The sound enrichment system of claim 21, wherein the at least one signal modulator is configured to adjust a level of the modulated noise signal based on the environmental classification.

29. The sound enrichment system of claim 21, wherein the output comprises a transducer, and wherein the transducer is configured to convert the modulated noise signal to an acoustic signal and is configured to present the acoustic signal to the user.

30. A method, comprising: receiving one or more sound signals; converting the one or more sound signals into a first output signal for compensation of a hearing loss of a user of a hearing device; generating, based on the one or more sound signals, an environmental classification of an auditory environment of the user; and generating a noise signal in dependence upon the environmental classification.

31. The method of claim 30, wherein generating the noise signal in dependence upon the environmental classification comprises: at least one of selectively activating or deactivating generation of the noise signal in dependence on the environmental classification.

32. The method of claim 30, wherein generating the noise signal in dependence upon the environmental classification comprises: modulating a first noise signal based on the environmental classification of the one or more sound signals.

33. The method of claim 32, wherein modulating the first noise signal based on the environmental classification of the one or more sound signals comprises: determining a type of noise present in the one or more sound signals; and modulating the first noise signal based on the type of noise present in the one or more sound signals.

34. The method of claim 32, wherein modulating the first noise signal based on the environmental classification of the one or more sound signals comprises: determining whether or not speech is present in the one or more sound signals; and modulating the first noise signal based at least in part on whether or not speech is present in the one or more sound signals.

35. The method of claim 30, further comprising: detecting speech present in the one or more sound signals; and setting a level of the noise signal based on the speech present in the one or more sound signals.

36. The method of claim 30, wherein generating the noise signal in dependence upon the environmental classification comprises: setting a level of the noise signal in dependence on the environmental classification.

37. The method of claim 30, further comprising: generating the noise signal based on a level of one or more sounds present in the auditory environment.

38. The method of claim 36, wherein generating the noise signal based on a level of one or more sounds present in the auditory environment comprises: obtaining a first noise signal; and modulating the first noise signal based on the level of the one or more sounds present in the auditory environment.

39. The method of claim 30, further comprising: combining the first output signal and the noise signal for presentation to the user.

40. The method of claim 30, wherein the noise signal comprises white noise.

Description

DESCRIPTION OF THE DRAWING FIGURES

[0073] Embodiments of the present invention are described herein in conjunction with the accompanying drawings, in which:

[0074] FIG. 1 shows a simplified block diagram of a sound enrichment system according to some embodiments,

[0075] FIG. 2 is a block diagram illustrating an embodiment of a sound enrichment system with a separate signal modulator,

[0076] FIG. 3 is a block diagram illustrating an alternative embodiment of a sound enrichment system,

[0077] FIG. 4 is a block diagram illustrating yet another embodiment of a sound enrichment system,

[0078] FIG. 5 is a block diagram illustrating yet another alternative embodiment of a sound enrichment system,

[0079] FIG. 6 shows one embodiment of a sound enrichment system forming part of a hearing aid,

[0080] FIG. 7 shows an alternative embodiment of a sound enrichment system forming part of a hearing aid,

[0081] FIG. 8 shows a simplified flow diagram of a method of providing a noise enriched sound signal for the provision of relief of tinnitus,

[0082] FIG. 9 shows an alternative embodiment of a sound enrichment system forming part of a hearing aid,

[0083] FIG. 10 schematically illustrates a binaural hearing aid system according to some embodiments, and

[0084] FIG. 11 shows an example of an attenuation curve for amplitude modulations of a noise signal as function of time.

DETAILED DESCRIPTION

[0085] The embodiments will now be described more fully hereinafter with reference to the accompanying drawings. The claimed invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Thus, the illustrated embodiments are not intended as an exhaustive description of the invention or as a limitation on the scope of the invention. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated. Like reference numerals refer to like elements throughout.

[0086] FIG. 1 shows a simplified block diagram of a sound enrichment system 2 according to some embodiments. The sound enrichment system 2 comprises a noise generator 4 for the provision of a noise signal having a certain average signal level. Also shown is an output transducer 6 that is configured to convert the noise signal to an acoustic signal that during use of the sound enrichment system 2 is presented to a user. As used in this specification, the term “noise signal” is not limited to the signal that is generated by the noise generator 4, and may refer to a modified signal that is derived from the signal generated by the noise generator 4. For example, the noise signal may be obtained by processing (e.g., delaying, factoring, filtering, modifying, etc.) the signal from the noise generator 4. The sound enrichment system 2 further comprises at least one signal modulator (not shown) that forms an integrated part of the noise generator 4. The signal modulator (not shown) is configured to randomly or pseudo-randomly modulate the noise signal to obtain a modulated noise signal. As used in this specification, the term “modulated noise signal” is not limited to the output signal from the signal modulator, and may refer to a modified signal that is derived from the signal output of the signal modulator. For example, the modulated noise signal may be obtained by processing (e.g., delaying, factoring, filtering, modifying, etc.) the signal output from the signal modulator. The integrated noise generator 4 and signal modulator (not shown) are thus configured to generate a random or pseudo-random modulated noise signal. The sound enrichment system 2 comprises furthermore an (optional) signal level adjuster 8, whereby the level of the noise signal may be adjusted. The signal level of the noise signal may for example be adjusted by the signal level adjuster 8 in dependence of a specific hearing loss of a user of the sound enrichment system 2, and/or the signal level of the noise signal may for example be adjusted in dependence of the type of the perceived tinnitus of a user of the sound enrichment system 2.

[0087] In order to account for nonlinearities in the output transducer 6, the sound enrichment system 2 may (optionally) comprise a receiver response equalization filter 10. Scientific investigations have, however, shown that in some practical implementations a receiver response equalization filter 10 may not be needed.

[0088] FIG. 2 is a block diagram illustrating an embodiment of the sound enrichment system 2 that comprises a separate signal modulator 12. The signal modulator 12 is configured to randomly or pseudo-randomly modulate the noise signal that is generated by the noise generator 4. In one embodiment of the sound enrichment system 2, the signal modulator 12 is configured to modulate the amplitude of the noise signal. In an alternative embodiment of the sound enrichment system 2, the signal modulator 12 is configured to modulate selected spectral characteristics of the noise signal. In yet an alternative embodiment of the sound enrichment system 2, the signal modulator 12 is configured to modulate both the amplitude and selected spectral characteristics of the noise signal.

[0089] FIG. 3 is a block diagram illustrating an alternative embodiment of the sound enrichment system shown in FIG. 2, wherein the signal modulator 12 modulates the noise signal, generated by the noise generator 4, by generating a randomly or pseudo-randomly varying modulation signal 14 for multiplication with the noise signal in the multiplier 22.

[0090] FIG. 4 is a block diagram illustrating yet another embodiment of the sound enrichment system 2 that comprises a spectral shaping filter 16 for (at least in part) filtering the noise signal, and wherein the at least one modulator 12 modulates selected spectral characteristics of the noise signal by a variation of the frequency response of the spectral shaping filter 16. Preferably, the signal modulator 12 generates a randomly or pseudo-randomly varying modulation signal 18 that is used to modulate the frequency response of the spectral shaping filter 16.

[0091] FIG. 5 is a block diagram illustrating yet another alternative embodiment of a sound enrichment system 2, wherein the modulator 12 generates two modulation signals, 18 and 20. The modulation signals 18 and 20 are preferably random or pseudo-random signals. In a preferred embodiment, the modulation signals 18 and 20 are generated independently of each other by the modulator 12. The signal 20 is used to modulate the amplitude of the noise signal, and the modulation signal 18 is used to modulate selected spectral characteristics of the noise signal by varying the frequency response of the spectral shaping filter 16. The modulation signals 18 and 20 are preferably different from each other and operate at different rates.

[0092] Note that any of the blocks illustrated in FIGS. 1-5 situated between the noise generator 4 and the output transducer 6 may be placed in any order.

[0093] The sound enrichment system 2 illustrated in any of the FIGS. 1-5 (preferably excluding the output transducer 6) may be provided as a personal portable device that is configured for being linked with at least one hearing aid, such as a single hearing aid or a binaural hearing aid system. Preferably, such a link is wireless, but the link may in an embodiment be wired.

[0094] FIG. 6 shows one embodiment of a sound enrichment system 2 forming part of a hearing aid 24. The hearing aid 24 comprises a microphone 26 for the provision of an input signal, a signal processor 28 that is configured to process the input signal according to a hearing impairment compensation algorithm in a hearing impairment compensation block 30, in order to provide a hearing impairment corrected output signal. The hearing aid further comprises an output transducer 6 (sometimes referred to as a receiver) that is configured to convert the hearing impairment corrected output signal into an acoustical signal that during use of the hearing aid is presented to a user. Here, the output transducer 6 of the sound enrichment system 2 is the output transducer of the hearing aid 24. The components of the sound enrichment system 2, thus forms an integral part of the hearing aid 24. The other components of the sound enrichment system 2 such as, the noise generator 4, the (optional) level adjuster 8, the (optional) receiver response equalization filter 10, the spectral shaping filter 16, and the signal modulator 12 (which signal modulator 12 in an alternative embodiment may form a part of the noise generator) may all be implemented in a software program stored on a machine readable data storage device which is executable on a processing device, such as for example the signal processor 28. Hereby is achieved that the main parts of the sound enrichment system 2 may be provided as an add-on software program to the general hearing aid software package (software implementations of hearing aid algorithms). Alternatively, only some of the components mentioned above may be implemented in a software program. For example the noise generator 4 and/or the signal modulator 12 may be implemented in a software program stored on a machine readable data storage device which when executed on a processing device, such as the signal processor 28, is configured to generate the modulated noise signal, and wherein the other components, such as the (optional) level adjuster 8, the (optional) receiver response equalization filter 10, and the spectral shaping filter 16 may be implemented in hardware. However, in a preferred embodiment, the spectral shaping filter 16 is implemented in a software program. In an embodiment, a software program stored on a machine readable data storage device comprises an implementation of the noise generator 4 and the signal modulator 12.

[0095] The modulated noise signal may be connected to adder 34 by the switch 36. The switch 36 may be implemented in software. Thus, when, during use, the switch 36 is enabled, the modulated noise signal will be added to the hearing impairment corrected output signal, and then subsequently converted to an acoustical noise signal in the transducer 6. The switch 36 may in one embodiment be controllable by a physical switch, like for example a toggle wheel or another form of mechanical or electrical (or optionally magnetic, magneto-resistive or giant magneto-resistive) contact in or on the hearing aid 24. Alternatively, the switch 36 may be software controlled. Such a software controlled switch 36 may for example be enabled or disabled by a user of the hearing aid 24, by a suitable choice of program(s) (usually a hearing aid user has the possibilities of choosing between a number of different programs, typically around 2-6 different programs).

[0096] For many tinnitus sufferers, the perceived tinnitus may be a highly time varying phenomenon. Some investigations show that this time variations may be stress related Thus, in one embodiment, the (optional) signal level adjuster 8 may, during use, be controlled by the volume control 38 of the hearing aid 24, the volume control 38 being adjustable by a user. This enables the user to adjust the level of the generated noise signal in dependence of the possibly time varying perceived tinnitus. Alternatively, the level adjuster may not be user controlled, but instead be adjusted to a default level (which would be adequate for some users), or individually adjusted by a professional in order to, during use, optimally provide the signal level needed for the noise signal in order to provide optimal relief of the perceived tinnitus of a user of the hearing aid 24.

[0097] Each (or any) of the embodiments of a sound enrichment system 2 shown in FIGS. 1-5 may form part of a hearing aid. Any of the blocks shown in FIGS. 1-5, preferably except the output transducer 6, may either individually or in any combination be implemented in a software product.

[0098] The at least one modulator 12 is configured to modulate the amplitude and/or the spectral characteristics of the noise signal. The modulator 12 is operatively connected to the signal path of the noise signal. Preferably the modulator 12 is operatively connected to the signal level adjuster 8. The modulator 12 may be configured to generate a randomly or pseudo-randomly varying amplitude modulation signal 20 that is multiplied to the noise signal, whereby amplitude modulation of the noise signal is achieved. Preferably, the modulator 12 is operatively connected to the signal level adjuster 8, whereby it is achieved that both an overall level adjustment of the noise signal and an amplitude modulation of the noise signal is achieved. The modulator 12 is furthermore operatively connected to the spectral shaping filter 16, the modulator 12 being configured to generate a randomly or pseudo-randomly varying spectral modulation signal 18 that is used as a control signal to randomly or pseudo-randomly vary selected spectral characteristics of the noise signal by a variation of the frequency response of the spectral shaping filter 16. In an alternative embodiment, the modulator 12 may be configured to only modulate either the amplitude or the spectral characteristics of the noise signal. In yet an alternative embodiment the modulator 12 may be configured to modulate the amplitude and spectral characteristics of the noise signal in steps subsequently after each other. The modulator 12 may in an alternative embodiment comprise two separate autonomous units.

[0099] The spectral shaping filter shown in FIG. 4 or FIG. 5 or FIG. 6 (or FIG. 7 described below or FIG. 9 described below) may comprise a band-pass filter, preferably a low-pass filter and a high-pass filter, for example such as IIR Butterworth filter(s) of second or third order or Chebychev filter(s).

[0100] The sound enrichment system 2 forming part of the hearing aid 24 may comprise a classifier 32. The classifier may form a part of the hearing impairment compensation block 30, which further may comprise a compressor (not shown). The hearing impairment compensation block 30 may partly be implemented in hardware and partly implemented in software. The classifier 32 may be operatively connected to the modulator 12, whereby is achieved that the modulation of the amplitude and/or spectral characteristics of the noise signal may be performed in dependence of a classification of the ambient sound environment. For example if there is noise present in the ambient sound environment then the modulation of the amplitude and/or spectral characteristics of the noise signal may be performed in such a way that the ambient noise level may in part be used in the sound enrichment. Alternatively, the classifier 32 may be directly operatively connected to the noise level adjuster 8 (direct connection not shown). Hereby is achieved that the level of the noise signal may be directly adjusted in dependence of a classification of the ambient sound environment. Since speech usually is a sound that is desirable for a user of the hearing aid 24 to hear, the generation of the noise signal may for example be turned off if speech is present in the ambient sound environment. In yet an alternative embodiment, the classifier 32 may be directly operatively connected to the spectral shaping filter 16 (direct connection not shown).

[0101] As mentioned before, scientific investigations show that, sound enrichment in openly fitted hearing aids is especially advantageous in order to achieve optimal habituation of a user's perceived tinnitus in a short period of time (typically a period of time below 8 months to 1 year). Some of the sound that is emitted by the output transducer 6 may leak back to the microphone 26 and then be amplified again in the hearing impairment compensation block 30. This problem is commonly referred to as feedback. This feedback problem is bigger in openly fitted hearing aids than more traditional hearing aids. Thus, in a preferred embodiment, the hearing aid 24 is configured to be openly fitted to a user, and furthermore comprise a feedback cancellation filter 40 that filters the output signal of the hearing impairment compensation block 30 and subtracts it from the input signal from the microphone 26 in the adder 42. The input to the feedback cancellation filter 40 may in one embodiment of the hearing aid 24 be tapped after the adder 34, and in an alternative embodiment tapped before the adder 34 as indicated by the dotted arrow 43.

[0102] FIG. 7 shows an alternative embodiment of a sound enrichment system 2 forming part of a hearing aid 24. The embodiment shown in FIG. 7 is essentially similar to the embodiment shown in FIG. 6, thus only the difference between them will be described. The difference between the embodiment shown in FIG. 7 as compared to the embodiment shown in FIG. 6, is that in FIG. 7 the classifier 32 does not form a part of the hearing impairment compensation block 30, but is implemented as an integral part of the sound enrichment system 2. The classifier 32 may in an alternative embodiment furthermore be operatively connected (not shown) to the hearing impairment compensation block 30. The classifier may be a neural network based classifier, a hidden Markov model classifier, or any other kind of classifier known in the art. The classifier 32 shown in FIG. 6 or FIG. 7 may be implemented in a software program.

[0103] FIG. 8 shows a simplified flow diagram of a method of providing a noise enriched sound signal for the provision of relief of tinnitus, the method comprising a step 44 of generating a noise signal, a step 46 of randomly or pseudo-randomly modulating (or adjusting) the noise signal, and a step 48 of generating an acoustic noise signal from the modulated noise signal, wherein the acoustic noise signal during use of the method is presented to a tinnitus suffering person. The step 46 of modulating the noise signal may comprise the sub steps of modulating the amplitude and/or selected spectral characteristics of the noise signal.

[0104] FIG. 9 shows an embodiment of a sound enrichment system 2 forming part of a hearing aid 24. The embodiment shown in FIG. 9 is essentially similar to the embodiment shown in FIG. 6, thus only the difference between them will be described. A difference between the embodiment shown in FIG. 9 and the embodiment shown in FIG. 6 is that the embodiment illustrated in FIG. 9 comprises a switch 50. The switch 50 may be implemented in software. In the embodiment illustrated in FIG. 9, the switch 50 has two positions, one wherein the volume control 38 is connected to the hearing impairment processing block 30, and another wherein the volume control 38 is connected to the signal level adjuster 8. Hereby, the volume control 38 can be switched between a position wherein the volume control 38 can be used to control the level of the noise signal generated by the noise generator 4, and a position wherein the volume control 38 can be used to control the level of the hearing aid gain that is applied in the hearing impairment compensation block 30. The switch 50 may in one embodiment be controllable by a physical switch, like for example a toggle wheel or another form of mechanical or electrical (or optionally magnetic, magneto-resistive or giant magneto-resistive) contact in or on the hearing aid 24. Alternatively, the switch 50 may be software controlled. Such a software controlled switch 50 may for example be enabled or disabled by a user of the hearing aid 24, by a suitable choice of program(s). Instead of two distinct positions for the switch 50, it may also be implemented as a “soft switch” that works in such a way that the volume control may be partly connected to the hearing impairment compensation block 30, and partly connected to the signal level adjuster 8. In an embodiment, the switch 50 may be operatively connected to the classifier 32, such that the adjustment of the switch 50 is performed in dependence of a classification of the ambient sound environment. For example if it is determined in the classifier 32 that the ambient sound environment is substantially quiet, then the switch 50 may be automatically switched to a position, wherein the volume control 38 will be connected to the level adjuster 8. This is due to the fact that a user may have greater benefit from using the volume control to adjust the signal level of the noise signal when the ambient environment is substantially quiet. Analogous, if it is determined in the classifier 32 that the ambient sound environment comprises speech then the switch 50 may be automatically switched to a position, wherein the volume control 38 will be connected to the hearing impairment compensation block 30. This is due to the fact that a user may have greater benefit from using the volume control to adjust the gain of the hearing aid 24 when the ambient environment comprises speech.

[0105] The switch 50 may be operatively connected to the switch 36, or to the noise generator 4, or to the modulator 12, such that the volume control may be used to control the sound enrichment system, i.e. to control whether the noise generator 4 is active or not, or whether the switch 36 is enabled or not, i.e. whether the noise signal generated by the sound enrichment system is added to the output signal from the hearing impairment compensation block 30 in the adder 34.

[0106] In an embodiment, the switch 50 as described with reference to FIG. 9 above may be implemented in a hearing aid as shown in FIG. 7.

[0107] In an embodiment of a sound enrichment system 2 forming part of a hearing aid 24 (illustrated in FIG. 6, FIG. 7, and FIG. 9) as well as an embodiment of a hearing aid 24 comprising a sound enrichment system 2, the modulated noise signal generated by the sound enrichment system 2 may be connected to an input of the hearing impairment correction block 30, e.g. by adding the modulated noise signal to the signal from the microphone 26 just before entering into the hearing impairment correction block. Such an implementation may replace the implementation illustrated in FIG. 6, FIG. 7, and FIG. 9, respectively, by the adder 34.

[0108] FIG. 10 schematically illustrates a binaural hearing aid system 56 according to some embodiments. The binaural hearing aid system 56 comprises a first hearing aid 52 and a second hearing aid 54.

[0109] The first hearing aid 52 comprises microphone 26 for the provision of a first input signal, an A/D converter 60 for converting the first input signal into a first digital input signal, a digital signal processor (DSP) 28 that is configured to process the digitalized first input signal, a D/A converter 62 for converting the processed first digital input signal into a first analogue output signal. The first analogue output signal is then transformed into a first acoustical output signal (to be presented to a first ear of a user) in a receiver 6.

[0110] Similarly the second hearing aid 54 comprises a microphone 26 for the provision of a second input signal, an A/D converter 60 for converting the second input signal into a second digital input signal, a digital signal processor (DSP) 28 that is configured to process the digitalized second input signal, a D/A converter 62 for converting the processed second digital input signal into a second analogue output signal. The second analogue output signal is then transformed into a second acoustical output signal (to be presented to a second ear of a user) in a receiver 6.

[0111] The binaural hearing aid system 56 furthermore comprises an (optional) link 58, between the two individual hearing aids 52 and 54. The link 58 is preferably wireless, but may in another embodiment be wired. The link 58 enables at least one of the two hearing aids 52 and 54 to communicate with the other, i.e. it may be possible to send information from at least one of the two hearing aids 52 and 54 via the link 58 to the other of the two hearing aids 52 or 54. In a preferred embodiment, the link 58 enables the two hearing aids 52 and 54 to communicate with each other. The link 58, thus, enables the two digital signal processors (both denoted 28 in FIG. 10), to perform binaural signal processing. Moreover, the link 58 enables the two hearing aids 52 and 54 to perform the modulations of the noise signals generated in the two hearing aids 52 and 54 in a coordinated manner. At least one of the hearing aids 52 or 54 comprises a sound enrichment system 2. Preferably, both of the hearing aids 52 and 54 comprise a sound enrichment system 2.

[0112] In a preferred embodiment, the first and second hearing aids 52, 54 are the hearing aid 24 shown in FIG. 6, 7, or 9. Hereby, it is achieved that the modulations of the amplitude and/or selected spectral characteristics of the noise signal may furthermore be performed in a coordinated, possibly asynchronous, manner between the two hearing aids 52 and 54. The modulations could for example comprise amplitude modulations and modulations of band pass filtering in the two hearing aids 52 and 54. Slightly asynchronous relations between the amplitude envelope and frequency band pass filtering between the two hearing aids 52 and 54 could make the modulated noise signal sound much like listening to breaking waves, as if the user of the binaural hearing aid system 56 was standing on a beach and listening to the waves. This way an even more comfortable noise signal for tinnitus relief is provided for. Alternatively or additionally, the modulations in the first hearing aid 52, could comprise amplitude modulations of the generated noise signal, and the modulations of the noise signal in the second hearing aid 54 could comprise modulations of selected spectral characteristics of the generated noise signal. The modulations of the amplitude and selected spectral characteristics of the noise signal may even be shifted between the two hearing aids 52 and 54, so that for example the first hearing aid 52 starts in a mode wherein it generates an amplitude modulated noise signal while the second hearing aid 54 generates a noise signal, wherein selected spectral characteristics of a noise signal is modulated. After a certain time span the roles of the two hearing aids 52 and 54 are reversed. This shifting between the modes of the two hearing aids 52 and 54 may continue as long as they are turned on, and the time span between the shifting may also be a randomly determined time span, or even be a time span that is modulated by another signal.

[0113] The hearing aids 52 and 54 forming part of the binaural hearing aid system 56 may in one embodiment be configured to operate in a master-slave configuration. In an embodiment of the binaural hearing aid system 56, the two hearing aids 52 and 54 are configured to operate in a master-slave configuration, and wherein only one of the two hearing aids 52 and 54 comprises a sound enrichment system 2. Hereby is achieved an embodiment wherein all the signal processing associated with the generation and modulation of the noise signal and the classification of the sound environment may be done in only one of the two hearing aids 52 or 54, and the wherein the thus modulated noise signal may simply be transferred to the other via the link 58. However, in a preferred embodiment, both hearing aids 52 and 54 comprise a sound enrichment system 2. Hereby is achieved that only signals used to control the sound enrichment system may need to be transferred from the master to the slave. This will lead to a considerable saving of the energy usage, because it may require at least five times as much battery power to transfer the noise signals itself from the master to the slave. It is furthermore, understood that in one embodiment of the binaural hearing aid system 56 only one of the two hearing aids 52 or 54, preferably the one of the hearing aids 52 or 54 that is configured as the master hearing aid, is equipped with a volume control 38 and possibly also a switch 50 as described above with reference to the embodiments shown in FIGS. 6, 7 and 9, and wherein the chosen (automatically or manually chosen) volume settings is automatically applied to the other hearing aid as well, via the link 58.

[0114] In yet another preferred embodiment of the binaural hearing aid system 56 according, each of the two individual hearing aids 52 and 54 forming part of the binaural hearing aid system 56 comprises a sound enrichment system 2, and each of them comprises a volume control, wherein the volume control of one of the hearing aids 52 or 54 is used to control the hearing aid gain in both hearing aids 52 and 54, and the volume control of the other hearing aid 52 or 54 is used to control the signal level of the noise signal generated by the sound enrichment system 2, in both hearing aids 52 and 54. Hereby is achieved a binaural hearing aid configuration, wherein the volume control on for example the left hearing aid may be used to control the hearing aid gain of both the left and the right hearing aid (via the link 58), and wherein the volume control on for example the right hearing aid may be used to control the hearing aid gain of both the right and the left hearing aid (via the link 58). Thus, only one volume control on each hearing aid is necessary in order to control the two features (hearing aid gain and level of the noise signal generated for the relief of tinnitus) of the binaural hearing aid system. Besides, it may not be needed that the volume control is configured to be switched between controlling the two features mentioned above.

[0115] FIG. 11 shows an example of an attenuation curve provided by the signal modulator 12 for amplitude modulations of noise signal as function of time. According to the illustrated example the signal modulator 12 calculates an attenuation curve that can be applied to the noise signal that is generated by the noise generator 4 in order to obtain a less monotonic noise signal. The signal modulator 12 may be configured in a number of ways to provide an attenuation curve which fits the user's requirements. For example the signal modulator 12 can be configured with the following properties: A curve attenuation level (chosen from en event space of modulation values) and a curve time period, also generally referred to as a modulation period (chosen from an event space of modulation periods).

[0116] The solid circles in FIG. 11 indicate a transition node. Each transition node is defined by the following properties: An attenuation level and a time span to the previous node in time. The time span from one node to the previous node in time is in an embodiment the modulation period. The attenuation level (also referred to as the modulation value) may be chosen by: Either setting the level of attenuation randomly or pseudo-randomly or by setting it to a fixed attenuation value, and similarly the time span to the previous node may be chosen by: Setting the time span to a random or pseudo-random value or by setting it to a fixed time span. The range of possible attenuation levels may be chosen from an event space of modulation values, and similarly the range of possible time spans between two successive nodes may be chosen from an event space of modulation periods.

[0117] In a preferred embodiment, the range of possible attenuation levels is limited, i.e., the event space of modulation values is preferably limited. For example it may be limited to attenuation levels in the range of 0 dB-20 dB, or 0 dB-15 dB, or 0 dB-12 dB, or alternatively to 0 dB-10 dB. In these mentioned examples the maximum level the attenuation may take is 20 dB, 15 dB, 12 dB or 10 dB, respectively. In FIG. 11 the dashed line illustrates an example of a maximum level of attenuation that can be applied by a modulator 12. Similarly, the time span between two successive nodes may be limited, i.e. the event space of modulation periods may be limited. For example it may be limited to time spans of 0-20 seconds, 1-15 seconds, 2-10 seconds or 2-8 seconds. Hereby is achieved an embodiment, wherein the modulator 12 may be configured to modulate the noise signal according to a method comprising the steps of: Randomly or pseudo- randomly choosing a modulation value from an event space of modulation values, and randomly or pseudo-randomly choosing a modulation period from an event space of modulation periods, i.e. a dual randomization may be achieved, because both the attenuation level, i.e. modulation value and the time span between two successive nodes, i.e. the modulation period, is randomly or pseudo-randomly chosen from the respective event spaces of modulation values and modulation periods, respectively.

[0118] Preferably, the hearing aid 24, 52, 54 processes sound signals in blocks of a certain number of samples, wherein the time distance between the samples is 1 divided by the sample frequency. As mentioned before the solid circles in FIG. 11 indicates a transition node. At these points in time a new set of parameters for the modulator 12 is found, i.e. a new time span and a new attenuation level. The time span between two transition nodes may correspond to several blocks being processed in the hearing aid 24, 52, 54. Thus a block counter variable may be used to keep track on when a time span has elapsed, thereby requiring a new set of parameters for the modulator 12 to be found.

[0119] The description of the amplitude modulations with reference to FIG. 11 may analogously be applied to the modulations of selected spectral characteristics of the noise signal. It is furthermore understood that the modulations as described with reference to FIG. 11 may be utilized in any other embodiments described in the present patent application, for example with reference to any of the embodiments shown in any of the other figures.

[0120] Although particular embodiments have been shown and described, it will be understood that they are not intended to limit the present inventions, and it will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present inventions. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. The claimed inventions are intended to cover alternatives, modifications, and equivalents.

LIST OF REFERENCES

[0121] In the following is given a list of reference numbers that are used in the detailed description. [0122] 2 sound enrichment system, [0123] 4 noise generator, [0124] 6 output transducer, [0125] 8 signal level adjuster, [0126] 10 receiver response equalization filter, [0127] 12 modulator, [0128] 14, 18, 20 randomly or pseudo-randomly varying modulation signal, [0129] 16 spectral shaping filter [0130] 22 multiplier, [0131] 24, 52, 54 hearing aid, [0132] 26 microphone, [0133] 28 sound processor, [0134] 30 hearing impairment compensation block, [0135] 32 environment classifier, [0136] 34 adder, [0137] 36 switch, [0138] 38 volume control, [0139] 40 feedback cancellation filter, [0140] 42 adder, [0141] 43 alternative input signal to the feedback cancellation filter, [0142] 44 method step of generating a noise signal, [0143] 46 method step of modulating a noise signal, [0144] 48 method step of generating an acoustic noise signal, [0145] 50 switch for volume control, [0146] 56 a binaural hearing aid system, [0147] 58 wireless link, [0148] 60 A/D converter, and [0149] 62 D/A converter.