METHOD FOR DETERMINING A HEAD RELATED TRANSFER FUNCTION AND HEARING DEVICE

Abstract

In a method for determining a head related transfer function an audio source outputs a source audio signal, namely both acoustically as a sound signal and also non-acoustically as a data signal. The sound signal is received by the hearing aid of a user and is converted by this hearing aid back into an audio signal, namely into a first audio signal, wherein the data signal is received by the hearing aid or by another device, which generates a second audio signal from the data signal, wherein the first audio signal and the second audio signal are compared to one another and the HRTF is determined based thereon. There is also described a corresponding hearing aid.

Claims

1-15. (canceled)

16. A method for determining a head related transfer function, the method comprising: a) outputting by an audio source a source audio signal, both acoustically as a sound signal and non-acoustically as a data signal; b) receiving the sound signal by a hearing aid of a user and converting the sound signal by the hearing aid back into a first audio signal; c) receiving the data signal and generating a second audio signal from the data signal; and d) comparing the first audio signal and the second audio signal to one another and determining the HRTF based thereon.

17. The method according to claim 16, wherein step c) comprises receiving the data signal and generating a second audio signal by the hearing aid or by another device.

18. The method according to claim 16, which comprises determining the HRTF by using the first audio signal as an intended signal and using the second audio signal as an actual signal.

19. The method according to claim 16, which comprises receiving the sound signal by the hearing aid using a microphone, and wherein the hearing aid is formed to be worn with the microphone positioned in or on an ear of the user.

20. The method according to claim 16, which comprises: ascertaining a spatial situation with respect to the user and taking the spatial situation into consideration in determining the HRTF; and selecting the spatial situation with respect to the user from a set of spatial situations from the group consisting of: a position of the user relative to the audio source; a distance of the user relative to the audio source; an orientation of the user relative to the audio source; an orientation of the head of the user relative to their torso; and a posture of the user.

21. The method according to claim 20, which comprises: for determining the HRTF, jointly storing as a data set a respective excerpt from the first audio signal and the second audio signal and a spatial situation with respect to the user; and controlling the audio source, upon a presence of a given spatial situation with respect to the user for which a minimum number of data sets is not yet provided, to output a source audio signal in order to generate a data set for the given spatial situation with respect to the user.

22. The method according to claim 20, which comprises outputting an instruction to the user to produce one or more spatial situations in each of which the audio source then outputs a source audio signal in order to generate a data set for each of the one or more spatial situations.

23. The method according to claim 16, which comprises: in a test mode of the hearing aid, outputting an output signal to the user with an item of spatial noise information in order to prompt the user to move in a given direction; and determining in which actual direction the user moves and comparing the actual direction with the given direction in order to ascertain a degree of adaptation of the HRTF to the user.

24. The method according to claim 16, which comprises determining the HRTF starting from a base HRTF, which is a transfer function for only a first section of an acoustic path from the audio source to an auditory canal of the user, and predominantly determining the HRTF for another, second section of the acoustic path.

25. The method according to claim 16, which comprises determining the HRTF by a computer, which is formed separately from the hearing aid and the audio source.

26. The method according to claim 16, wherein the audio source is a stationary device.

27. The method according to claim 16, wherein the audio source is a television device.

28. The method according to claim 27, which carrying out the method steps while the user is watching television.

29. The method according to claim 16, which comprises controlling the audio source to outputs the source audio signal as a sound signal via only a single loudspeaker.

30. The method according to claim 16, which comprises determining an acoustic parameter of the environment and taking the acoustic parameter of the environment into consideration in determining the HRTF.

31. A hearing aid, comprising a control unit configured to carry out the method according to claim 16.

Description

[0047] Exemplary embodiments of the invention are explained in more detail hereinafter on the basis of a drawing. In the schematic figures:

[0048] FIG. 1 shows an environment having an audio source and a user having a hearing aid,

[0049] FIG. 2 shows an acoustic path,

[0050] FIG. 3 shows a hearing aid,

[0051] FIG. 4 shows the determination of an HRTF from multiple data sets,

[0052] FIG. 5 shows an audio source, a hearing aid, and a computer.

[0053] A core concept of the present invention is illustrated in FIG. 1, namely to use an audio source 6, which can output a source audio signal 8 both acoustically and also non-acoustically, to determine an HRTF 2 for a specific user 4. The audio source 6 is a media device here and especially a TV device. The audio source 6 is used repeatedly by the user 4 in their everyday life. The acoustically output audio signal propagates along an acoustic path 10 to the user and especially to a microphone 12 of a hearing aid 14 of the user 4 and is modified along the acoustic path 10 by the body shape of the user 4.

[0054] An exemplary acoustic path 10 is shown in FIG. 2 and contains multiple sections 16, 18, 20. A first section 16 is defined by a first modification, which takes place independently of the user 4 due to the environment and is not of further importance here. A second section 18 is defined by a second modification which takes place due to the body shape (primarily torso shape) and head shape of the user 4. The second section 28 forms the acoustic path 10 via/along/through the body of the user 4 up to the ear or up to behind the ear of the user 4. A third modification 20 takes place due to the ear, especially the pinna of the user 4, and thus defines a third and also last section 20 here of the acoustic path 10 from outside the ear up into the auditory canal of the user 4. The sections 18, 20 are defined by a transfer function which corresponds to the actual, individual HRTF of the user 4. The non-acoustically output audio signal, in contrast, is in particular not modified by this HRTF 2, so that the HRTF 2 may be determined individually for the user by a comparison of the two differently transferred audio signals.

[0055] The method described here is generally used to determine an HRTF 2 (i.e., “head-related transfer function”). The determination of the HRTF 2 is carried out in a user-specific manner for a specific user 4. The audio source 6 outputs the source audio signal 8, namely both acoustically as a sound signal 22 and also non-acoustically as a data signal 24. The source audio signal 8 is an audio signal and as such is an electrical signal. For the acoustic output of the source audio signal 8, the audio source 6 has a loudspeaker 26. The same source audio signal 8 is also output on a further, non-acoustic channel, namely as the data signal 24. For the non-acoustic output of the source audio signal 8, the audio source 6 has a data output 28, in the exemplary embodiment shown an antenna for a wireless radio connection. A wired emission is also possible, however, the data output 28 is then a corresponding terminal. It is initially only essential that the same source audio signal 8 is output on two different channels, namely once acoustically as the sound signal 22 and once non-acoustically as the data signal 24.

[0056] The sound signal 22 is received by the hearing aid 14 and converted thereby back into an audio signal, namely into a first audio signal 30, which is also referred to as an “acoustically transferred audio signal”. Especially in a hearing aid 14 for treating a hearing-impaired user 4, receiving sound signals 22 from the environment is an original function of the hearing aid 16. The data signal 24 is received by the hearing aid 14 or by another device 32, which generates a second audio signal 34 from the data signal 24. For this purpose, the hearing aid 14 or the other device 32 accordingly has a data input 44, for example, an antenna. The other device 32 is an auxiliary device in the exemplary embodiment shown, which is connected for data exchange to the hearing aid 14, for example, a smart phone. The second audio signal 34 is also referred to as a “non-acoustically transferred audio signal”.

[0057] The first audio signal 30 and the second audio signal 34, i.e., the audio signals transferred on different channels, are compared to one another and based thereon, i.e., based on the comparison, the HRTF 2 is determined. The second audio signal 34 typically substantially corresponds to the source audio signal 8 and has at least not been influenced by the HRTF 2. In contrast thereto, the sound signal 22 was modified by the HRTF 2, so that the first audio signal 30 accordingly differs from the source audio signal 8. To determine the HRTF 2, for example, the first audio signal 30 is then used as an intended signal and the second audio signal 34 as an actual signal.

[0058] The HRTF 2 determined in the above-mentioned manner is stored in the present case in the hearing aid 14 and used by a signal processing unit 36 of the hearing aid 16 in operation, in order as a result to adapt the sound signal which is output by the hearing aid 14 to the user 4. An exemplary hearing aid 14 is shown in FIG. 3. The hearing aid 14 shown here is, without restriction of the generality, a hearing aid 14 for the treatment of a hearing-impaired user 4. However, the invention is also applicable to other hearing aids 16, for example, a set of headphones which additionally has one or more microphones. The hearing aid 14 shown here has an input transducer (namely the microphone 12), the above-mentioned signal processing unit 36, and an output transducer 38, a receiver here. The input transducer generates an input signal which is supplied to the signal processing unit 36. In the present case, the input transducer especially also generates the first audio signal 30, which is accordingly an input signal. The signal processing unit 36 modifies the input signal and thus generates an output signal, which is thus a modified input signal. To compensate for a hearing loss, the input signal is amplified, for example, according to an audiogram of the user 4 using a frequency-dependent amplification factor. Alternatively or additionally, the input signal is modified in dependence on the HRTF 2. The output signal is finally output by means of the output transducer 38 to the user 4.

[0059] In the embodiment shown here, to determine the HRTF 2, only excerpts 40, so-called samples, are taken from each of the first and the second audio signal 30, 34 and stored as a data set 42. This is illustrated in FIG. 4. The two excerpts 40 (one excerpt 40 from the first audio signal 30 and one excerpt 40 from the second audio signal 34) of a respective data set 42 also originate here from the same time interval or have a corresponding timestamp. A large number of data sets 42 are typically recorded and stored and evaluated to determine the HRTF 2. This takes place either on the hearing aid 14, on an auxiliary device as described, or on a separate computer, for example, a server.

[0060] The above-described recording and further output of a sound signal with modification on the electrical level is the normal case in operation of the hearing aid 16, this is also referred to as the “normal mode” of the hearing aid 16. In addition to the normal mode, the hearing aid 14 described here also has a streaming mode in which the output to the user 4 is based on the data signal 24 which is emitted by the audio source 6. In the streaming mode, a conversion into and back conversion out of a sound signal is dispensed with and an audio signal is transferred from the audio source 6 in a lossless and uninfluenced manner to the user 4. The streaming mode is used, for example, to transfer an audio signal 8 from a TV device, computer, or smart phone and in general from an audio source 6 to the hearing aid 14. The hearing aid 14 accordingly has a data input 44, which is made complementary to the data output 28 of the audio source, accordingly also as an antenna here.

[0061] In the present case, the functionalities of the normal mode and the streaming mode are now unified to determine the HRTF 2. The hearing aid 14, on the one hand, receives the sound signal 22 from the audio source 6 by means of the microphone 12 and thus uses the functionality of the normal mode. On the other hand, the hearing aid 14 receives the data signal 24 from the audio source 6 and thus uses the functionality of the streaming mode. Which of the two audio signals 30, 34 is then actually also output again via the output transducer 38 to the user 4 is not important and remains left, for example, to the user.

[0062] For the method described here, however, it is not absolutely necessary that the hearing aid 14 has a streaming mode or in general receives the data signal 24, this can also be received by another device 32. The first and the second audio signal 30, 34 solely have to be brought together on any arbitrary device, in order to be compared there and to determine the HRTF 2 based thereon.

[0063] However, it is important for the correct determination of the HRTF 2 that the hearing aid 14 receives the sound signal 22, because the hearing aid 14 is worn by the user 4, while any other device 32 is generally positioned outside the user 4 and is therefore not suitable for receiving a sound signal 22 which propagates along the acoustic path 10 to the user 4. In the embodiment shown here, the hearing aid 14 accordingly receives the sound signal 22 using a microphone 12, which is a part of the hearing aid 16. The hearing aid 14 shown here is moreover designed in such a way that in the worn state, the microphone 12 is positioned in or on an ear of the user 4. The precise position of the microphone 12 is dependent on the type of the hearing aid 16. In a BTE device, the microphone 12 is positioned behind the ear, in an RIC device in the auditory canal, and in an ITE device in the ear, but still before the auditory canal. Therefore, the entire acoustic path 10 up into the auditory canal is possibly not taken into consideration and the HRTF 2 is accordingly only determined for one or individual sections 18, 20 of the acoustic path 10. The hearing aid 14 is either monaural and is then worn only on one side (left or right) of the head or—as shown here—is binaural and then has two individual devices which are worn on different sides of the head (i.e., left and right). In a binaural hearing aid 14, both individual devices each have one or more microphones 12.

[0064] In the exemplary embodiment shown here, the spatial situation with respect to the user 4 is also taken into consideration in the determination of the HRTF 2, especially their relative spatial relationship to the audio source 6 here. The spatial situation is characterized in the exemplary embodiment shown by a position 46, distance 48, and/or orientation 50 of the user 4 relative to the audio source 6. In one variant (not explicitly shown), the spatial situation is alternatively or additionally especially an orientation of the head of the user 4 relative to their torso or in general a posture of the user 4. Other postures are, for example, seated, lying, standing. The acoustic path 10 is generally dependent on how the body of the user 4 is aligned relative to the audio source 6 or which posture the user 4 assumes, i.e., whether the sound signal 22 reaches the user 4 from the front, from the rear, or from the side and how their own body, especially the torso, shades the sound signal. Accordingly, the modification of the sound signal 22 during its propagation to the user 4 is dependent on the relative spatial relation between user 4 and audio source 6 and the posture of the user 4, so that the HRTF 2 is also situation-dependent and especially direction-dependent and posture-dependent. Data sets 42 are therefore recorded in as many different relative spatial situations as possible, i.e., for as many different positions 46, distances 48, orientations 50, and/or postures as possible. How precisely the spatial situation, e.g., the position 46, distance 48, and/or orientation 50 of the user 4 relative to the audio source 6 is determined is of secondary importance in the present case and is therefore not further subject matter. In any case, a respective excerpt 40 from the first and the second audio signal 30, 34 and a spatial situation are jointly stored as a data set 42 for determining the HRTF 2, so that a respective data set 42 then also contains an item of information about the spatial situation.

[0065] Generating data sets 42 is possible in greatly varying ways, in particular with different degrees of participation of the user 4 and with or without a special actuation of the audio source 6.

[0066] First, an embodiment is possible in which data sets 42 are generated progressively, without the user 4 having to be active at all or the audio source 6 having to be specially controlled. The method is therefore executed so to speak in the background during intended use and thus does not annoy the user 4.

[0067] Alternatively or additionally, the audio source 6 is controlled in such a way that it outputs a source audio signal 8 when a spatial situation is present for which a minimum number of data sets 42 is not yet provided, in order to generate a data set 42 for this spatial situation. In this embodiment, the audio source 6 is accordingly specially controlled to deliberately generate a data set 42 for those spatial situations for which sufficiently many data sets 42 for a sufficiently good determination of the HRTF 2 are not yet provided. How many data sets 42 are actually required for a respective spatial situation, thus how large the minimum number is, is primarily not important. For example, the minimum number is only 1 or alternatively 10, 100, or 1000. A participation of the user 4 is also not required in this embodiment, however, a special actuation of the audio source 6 is carried out to deliberately generate as many reasonable data sets 42 as possible.

[0068] Alternatively or additionally, an instruction is output to the user 4 to produce one or more spatial situations in each of which the audio source 6 then outputs a source audio signal 8 to generate a data set 42 for each of these spatial situations. The instruction is output, for example, by the hearing aid 14, the audio source 6, or another device 32. The instruction is, for example, acoustic or optical. Whether the user 4 actually follows the instruction remains left to himself or herself. The method then overall uses a participation of the user 4, a special actuation of the audio source 6 is not absolutely required, however.

[0069] Alternatively or additionally, the hearing aid 14 has a test mode and in this mode outputs an output signal to the user 4, which has an item of spatial noise information (i.e., “spatial cue”, for example, a spatially localized noise), to prompt the user 4 to move or orient themselves in a provided direction, namely in particular toward where the noise supposedly comes from. Furthermore, it is then determined in which actual direction the user 4 moves or orients themselves and this is compared to the provided direction in order to ascertain a degree of adaptation of the HRTF 2 to the user 4. The degree of adaptation then indicates, for example, how well the presently determined HRTF 2 corresponds to the actual HRTF 2. The test mode thus enables a check of the HRTF 2 determined up to this point and also an ascertainment of how well it corresponds to the actual HRTF 2 for the user 4.

[0070] As is already recognizable in FIG. 2, the HRTF 2 can in principle itself be decomposed into multiple individual transfer functions, which model individual sections (for example, the sections 18, 20) of the acoustic path 10 and which then result in the HRTF 2 for the entire acoustic path 10 when joined together. Under certain circumstances, it is not necessary or is even impossible to determine the HRTF 2 for the entire acoustic path 10 in the described manner, but rather only for one or more individual sections 18, 20, especially those sections 18, 20 which are closest to the user 4, above all the third section 20 here. The remaining sections 18 are then modeled, for example, by means of a respective standard function, especially also the section 16 which as such does not contribute to the HRTF, but the determination of which possibly corrupts it.

[0071] In one possible embodiment, the determination of the HRTF 2 is carried out starting from a base HRTF, which is a transfer function for only a first section 18, 20 of an acoustic path 10 from the audio source 6 to the auditory canal of the user 4, so that the HRTF 2 is predominantly determined for another, second section 18, 20 of the acoustic path 10. For example, the second section in particular contains that part of the acoustic path 10 which contains the pinna, the third section 20 in FIG. 2 here. The base HRTF is then, for example, an HRTF 2 of a dummy and predominantly takes into consideration the body shape and general head shape of the user 4. This base HRTF is then optimized by the present method in such a way that the special shape of the pinna of the user 4 is taken into consideration, so that overall the HRTF 2 is determined in a user-specific manner. For this purpose, the hearing aid 14 is designed, for example, in such a way that is microphone 12 is positioned in the worn state in the auditory canal or in the ear of the user 4 and not solely behind the ear.

[0072] The HRTF 2 is not necessarily determined by the hearing aid 14. In FIG. 5, for example, the HRTF 2 is determined by a computer 52, a server here, which is formed separately from the hearing aid 14 and the audio source 6. Precisely how the data sets 42 reach the server for this purpose is not of further relevance and is also dependent on the selected embodiment of the method, the hearing aid 14, the audio source 6, and other possibly participating devices 32. FIG. 5 insofar only shows one of many possible embodiments. Embodiments are possible, for example, in which the hearing aid 14 transmits the first, acoustically transferred audio signal 30 or excerpts 40 thereof to the server, the second, acoustically transferred audio signal 34 or excerpts 4 thereof are also transmitted by the hearing aid 14 or by another device 32, for example, a smart phone or the audio source 6, to the server, which then transmits the HRTF 2 to the hearing aid 14.

[0073] In the exemplary embodiment shown in FIG. 1, the audio source 6 is a stationary device and typically remains at the same point in the environment, for example, a room as shown, while the user 4 moves in relation to the audio source 6 and in general the spatial situation changes. Such a movement of the user 4 is illustrated in FIG. 1 by an exemplary movement path 54. Moreover, the audio source 6 is a TV device in the embodiment shown here. As is recognizable in FIG. 1, the user 4 typically stops at a distance of a few meters relative to the TV device, which is similar to the distance in the determination of an HRTF 2 in an echo-free room as described at the outset. In addition, the TV device is typically always placed at the same position in the environment, so that additional room-acoustic effects, especially along the first section 16, are taken into consideration better in the determination of the HRTF 2. The method described here is also then carried out especially while the user 4 watches television, i.e., while the audio source 6 is switched on and the user 4 stops in its close environment (for example, within less than 5 m distance from the audio source 6). It is not absolutely required here that the user 4 follows the content emitted by the TV device or gives it special attention. In one possible embodiment, the audio source 6 is moreover controlled in such a way that it only outputs the audio signal 8 as a sound signal 22 via a single loudspeaker 26, so that the acoustic path 10 is defined more accurately.

[0074] In addition, in one embodiment an acoustic parameter of the environment is also determined, in order to quantify one or more room-acoustic effects, and taken into consideration in the determination of the HRTF 2. A transfer function for the first section 16 is thus determined here. Room-acoustic effects are, for example, reflections of the sound signals on walls or objects in the environment or a reverberation, especially in a room. The acoustic parameter is determined, for example, using the hearing aid 14 or using another device 32.

[0075] The hearing aid 14 furthermore has a control unit 56, which is designed to carry out the method as described above, at least those steps of the method which are carried out by the hearing aid 14.

LIST OF REFERENCE NUMERALS

2 HRTF

[0076] 4 user
6 audio source
8 source audio signal
10 acoustic path
12 microphone
14 hearing aid
16 first section
18 second section
20 third section
22 sound signal
24 data signal
26 loudspeaker (of the audio source)
28 data output
30 first audio signal (from sound signal)
32 other device
34 second audio signal (from data signal)
36 signal processing
38 output transducer
40 excerpt (sample)
42 data set
44 data input
46 position
48 distance
50 orientation
52 computer (server)
54 movement path
56 control unit