METHOD FOR TRANSMITTING AN AUDIO SIGNAL, HEARING DEVICE AND HEARING DEVICE SYSTEM

Abstract

An audio signal is transmitted from a transmitter to a receiver in a hearing device, particularly a hearing aid. A communication facility configured for transmitting and/or receiving the audio signal. A hearing device system has two hearing devices configured to transmit audio signals between the two hearing devices by way of their communication facilities in accordance with the method.

Claims

1. A method for transmitting an audio signal from a transmitter to a receiver, the method comprising: at a transmitter end: dividing an input signal representing the audio signal into a plurality of channels for a particular time window; allocating a current channel value to each channel of the plurality of channels; generating a plurality of prognostic values by way of preceding channel values that are allocated to a time window preceding in time, and allocating one of the prognostic values to each current channel value; determining a reference value; determining a gain factor by way of the reference value and allocating the gain factor to one of the prognostic values, and modifying the current channel value associated with the one prognostic value by the gain factor to form an adapted channel value; allocating the adapted channel value to an adapted data record; transmitting a transmission value corresponding to the adapted data record from the transmitter to the receiver; at a receiver end: generating a reconstructed adapted data record with a reconstructed adapted channel value which corresponds to the adapted channel value by way of the transmission value; generating a plurality of receiver-end prognostic values by way of reconstructed preceding channel values, one of the receiver-end prognostic values being allocated to the reconstructed adapted channel value; allocating a receiver-end gain factor to the reconstructed adapted channel value by way of the allocated receiver-end prognostic value; modifying the reconstructed adapted channel value by way of the receiver-end gain factor to form a reconstructed channel value; and adding the reconstructed channel value to a reconstructed output signal.

2. The method according to claim 1, which comprises using a maximum of the prognostic values as the reference value.

3. The method according to claim 2, which comprises: at the transmitter end, allocating the current channel value, to which the maximum of the prognostic values is allocated, to the adapted data record; at the receiver end, generating the reconstructed adapted data record using the transmission value with the reconstructed adapted channel value that corresponds to the adapted channel value and with a reconstructed unadapted channel value that corresponds to the current channel value allocated to the maximum of the prognostic values; and at the receiver end, combining the reconstructed channel value and the reconstructed unadapted channel value to form the reconstructed output signal.

4. The method according to claim 1, which comprises choosing the gain factor such that a deviation between the prognostic value allocated to the gain factor and the reference value would be greater than a deviation between the reference value and the prognostic value modified by way of the gain factor.

5. The method according to claim 1, which comprises using as the prognostic value (54 the preceding channel value allocated to the same channel.

6. The method according to claim 1, which comprises generating the gain factor and the receiver-end gain factor by way of the prognostic value to which the gain factor is allocated and, respectively, by way of the receiver-end prognostic value which is allocated to the reconstructed adapted channel value.

7. The method according to claim 6, which comprises generating the gain factor from a difference between the reference value and the prognostic value.

8. The method according to claim 1, which comprises allocating a gain factor to each of the remaining prognostic values.

9. The method according to claim 8, wherein the gain factors differ from one another.

10. The method according to claim 1, which comprises dividing the input signal into the frequency channels by way of band-pass filters.

11. The method according to claim 1, which comprises generating the transmission value by quantizing the adapted data record.

12. The method according to claim 11, which comprises, a the transmitter end, generating by way of the transmission value and the gain factor a transmitter-end reconstructed channel value, which corresponds to the reconstructed channel value and which, during a transmission following in time, is utilized as one of the channel values preceding in time.

13. The method according to claim 11, which comprises quantizing utilizing a vector quantization.

14. The method according to claim 11, which comprises quantizing utilizing a spherical logarithmic quantization.

15. A hearing device, comprising a communication facility having a transmitter and a receiver configured for transmitting and/or receiving an audio signal by carrying out the method according to claim 1.

16. The hearing device according to claim 15 configured as a hearing aid.

17. A hearing device system, comprising two hearing devices each having a communication facility with a transmitter and a receiver configured for transmitting audio signals between said two hearing devices, each said communication facility being configured for transmitting and/or receiving the audio signals by carrying out the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0061] FIG. 1 shows diagrammatically a hearing device system with two hearing devices;

[0062] FIG. 2 is a flow diagram illustrating a method for transmitting an audio signal between the two hearing devices;

[0063] FIG. 3 shows an input signal corresponding to the audio signal;

[0064] FIG. 4 shows the input signal divided into a number of channels;

[0065] FIG. 5 shows current channel values;

[0066] FIG. 6 shows prognostic values;

[0067] FIG. 7 shows an adapted data record;

[0068] FIG. 8 diagrammatically shows sections of the hearing device system; and

[0069] FIG. 9 shows a reconstructed adapted data record and a reconstructed output signal.

[0070] Parts and elements that correspond to one another are identified with the same reference symbols in all figures.

DETAILED DESCRIPTION OF THE INVENTION

[0071] Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is shown a hearing device system 2 having two structurally identical hearing aids 4, which are provided and configured to be worn behind an ear of a user. In other words, they are in each case a “behind-the-ear” hearing aid which has a non-illustrated sound tube, or acoustic tube, which is introduced into the ear to connect a receiver in the ear canal. Each hearing aid 4 comprises a housing 6 which is manufactured from a plastic material. Within the housing 6, a microphone 8 having two electromechanical sound transducers 10 is arranged. By means of the two electromechanical sound transducers 10, a directional characteristic of the microphone 8 can be changed in that a temporal offset between the acoustic signals detected by way of the respective electromechanical sound transducer 10 is changed. The two electromechanical sound transducers 10 are coupled with respect to signals to a signal processing unit 12 which comprises an amplifier circuit. The signal processing unit 12 is formed by means of circuit elements such as, for example, electrical and/or electronic components.

[0072] Furthermore, the signal processing unit 12 is connected to a loudspeaker 14 by means of which the audio signals 16 recorded by the microphones 8 and/or processed by the signal processing unit 12 are output as sound signals. These sound signals are conducted into the ear of a user of the hearing device system 2 by way of the acoustic tube.

[0073] Each of the hearing aids 4 also has a transmitter 18 and a receiver 20, also referred to as a transceiver, by means of which data signals 22 are exchanged between the two hearing aids 4. The exchange is wireless, for example by means of radio or inductive transmission. The signal processing unit 12, the transmitter 18 and the receiver 20 here together in each case form a communication facility 24. The exchange of the data signals 22 enables a spatial hearing sensation to be conveyed to the wearer of the hearing device system 2. In summary, the hearing device system 2 is a binaural system.

[0074] In FIG. 2, a method 26 is shown according to which the audio signals 16 are transmitted between the two hearing devices 4 by means of their respective communication facility 24. In a first operating step 28, the audio signal 16 is received by means of one of the hearing aids 4. In a subsequent second operating step 30, an input signal 32 is generated from this which, in consequence, corresponds to the audio signal 16 and which is shown in FIG. 3 by way of example. For this purpose, the audio signal 16 is especially filtered. Furthermore, the input signal 32 is subdivided into time windows 34 which have the same length in time and which, for example, is equal to one millisecond. As soon as the last time window 34 in time is ended, this time window 34 is divided into a number of channels 36 as shown, for example, in FIG. 4. The channels 36 are frequency channels and for dividing the input signal 32 into the individual frequency channels 36, frequency-pass filters 38 are utilized which are present within the signal processing unit 16. Furthermore, the input signal 32 only comprises the channels 36 whereas the audio signal 16 has the channels 36 and yet further frequency channels. To each of the frequency channels 36, a particular current channel value 40 is allocated. In summary, the input signal 32 is divided into the individual frequency channels 36 in the second operating step 30 and discretized by means of the allocation of the current channel value 40.

[0075] Furthermore, after execution of the first operating step 16 at the transmitter 18, a third operating step 42 is carried out in which channel values 44 preceding in time are filled. These have been determined, for example, in a preceding run of the method 26 or, if the method 26 has not yet been carried out, standard values are utilized for this purpose such as zero (0). As well, a fourth operating step 46 is carried out at the receiver 20 in which reconstructed preceding channel values 48 are determined. These correspond to the channel values 44 preceding in time and are determined in the same way as the channel values 44 preceding in time.

[0076] In FIG. 5, the current channel values 40 are shown, each of which is in each case allocated to a channel 36. One of the current values 40 is comparatively large in this case. In an application of a spherically logarithmic quantization to the input signal 32, a first noise level 50 would be introduced due to the increased current channel value 40 which is greater than the remaining actual channel values 40 in wide parts such that these values would be excessively corrupted.

[0077] In a fifth operating step 52, therefore, a number of prognostic values 54 is therefore generated at the transmitter end by means of the preceding channel values 44, each of the prognostic values 54 being allocated to one of the channels 36 and thus also to one of the current channel values 40, as shown in FIG. 6. The channel value 44 preceding in time allocated to the same channel 36 is utilized as prognostic value 54.

[0078] In a subsequent sixth operating step 56, a reference value 58 of the prognostic values 54 is determined, the maximum of the prognostic values 54 being utilized as reference value 58. In other words, the largest of the prognostic values 54 and thus the largest of the preceding channel values 44 is determined.

[0079] To the remaining prognostic values 54 is allocated a gain factor 62 in each case in a seventh operating step 60, the gain factors 62 differing. Thus, gain factors 62 are allocated to the channels 36 for the time window 34, each of the gain factors 62 being allocated to precisely one of the current channel values 40—with the exception of the current channel value 40 to which the reference value 68 is allocated. Each of the gain factors 62 is determined with the formula

G.sub.i=wΔL.sub.i

where w is an arbitrary factor between zero (0) and one (1), for example 0.5. G.sub.i is the gain factor 62 which is allocated to channel 36 having the index i. ΔL.sub.i designates the difference 64 between the reference value 58 and the prognostic value 54 which is allocated to the channel 36 having the index i. In consequence, all of the gain factors 62 differ and the respective gain factor 62 is generated by means of the respectively allocated prognostic value 54 to which the gain factor 62 is allocated.

[0080] In a subsequent eighth operating step 68, each of the current channel values 40 is modified by means of that gain factor 54 which is allocated to the respectively allocated prognostic value 54 and generated by means of the latter. Thus, each of the current channel values 40, with the exception of that current channel value 40 to which the reference value 58 is allocated and to which, in consequence, none of the gain factors 52 is allocated, is modified to form an adapted channel value 70. The respective current channel value 40 is multiplied by the gain factor 62 allocated in each case as, for example, shown diagrammatically in FIG. 8. Thus, the respective gain factor 54 is chosen in such a manner that a deviation between the allocated prognostic value 54 and the reference value 58 would be greater than a deviation between the reference value 58 and the prognostic value modified by means of the gain factor 54. Since the current channel values 40 in most cases deviate only comparatively little from the respective channel value 44 preceding in time, the deviation between the current channel value 40 to which the reference value 58 is allocated and the adapted channel values 70 is thus also reduced.

[0081] The adapted channel values 70 and the current channel value 40 to which the reference value 58 is allocated are allocated to an adapted data record 72 which is thus a vector which has precisely the same number of elements as there are current channel values 40. In a ninth operating step 74, the adapted data record 72 is quantized by means of a spherically logarithmic quantization and a transmission value 76 is formed which is unidimensional in consequence. In other words, the transmission value 76 is generated by means of quantization of the adapted data record 72, the spherically logarithmic quantization being utilized as quantization. Due to the quantization, a second noise level 78 is introduced into the adapted data record 72. The transmission value 76 is transmitted to the remaining hearing device 4 as component of the data signal 22.

[0082] The transmission value 76 is received by means of the receiver 20 and a tenth operating step 80 is carried out in which a reconstructed adapted data record 82, which is shown in FIG. 9, is generated by means of the transmission value 76 at the receiver end. This corresponds to the adapted data record 72 with the exception of any noise which has been introduced due to the quantization. In other words, the reconstructed adapted data record 82 has a number of reconstructed adapted channel values 84 corresponding to the number of adapted channel values 70, each of the reconstructed adapted channel values 84 corresponding to one of the adapted channel values 70 and, in particular, conforming to this one. Furthermore, the reconstructed adapted data record 82 has a reconstructed unadapted channel value 86 which corresponds to the current channel value 40 allocated to the reference value 58 of the prognostic values 54 and thus is essentially the only current channel value 40 which, with the exception of the quantization, has been transmitted essentially unchanged from the transmitter 18 to the receiver 20.

[0083] In an eleventh step 88, a number of receiver-end prognostic values 90 is generated at the receiver end by means of the reconstructed preceding channel values 46, one of the receiver-end prognostic values 90 being allocated in each case to the reconstructed adapted channel values 84 and the reconstructed unadapted channel value 86. In a twelfth operating step 92, a maximum of the receiver-end prognostic values 92 is determined and in this way the reconstructed unadapted channel value 86 is identified within all values of the reconstructed adapted data record 82. In a subsequent thirteenth operating step 84, receiver-end gain factors 96 are determined by means of the receiver-end prognostic values 90 and the receiver-end maximum of the receiver-end prognostic values 90. Each of the receiver-end gain factors 96 is in each case allocated to one of the reconstructed adapted channel values 84 and the respective receiver-end prognostic values 90. Since the reconstructed preceding channel values 48 substantially correspond to the preceding channel values 44, the prognostic values 54 and the receiver-end prognostic values 90 correspond to one another. For the determination of the receiver-end gain factors 96, the same calculating rule is used as for determining the gain factors 62 which is present at the transmitter 18. The receiver-end gain factor 96 which corresponds to the transmitter-end gain factor 62 is here allocated to the same channel 36.

[0084] In summary, the eleventh, twelfth and thirteenth operating step 88, 92, 94 essentially correspond to the fifth, sixth and seventh operating step 52, 56, 60, wherein, however, different input data are utilized, namely one time the channel values 44 preceding in time and the other time the reconstructed preceding channel values 48 which, however, are equal due to the fourth operating step 46 and the third operating step 42. Thus, each gain factor 62 is equal to the transmitter-end gain factor 96 which is allocated to the same channel 36 in each case. Transmission of the gain factor 96 from the transmitter 18 to the receiver 20 is not required.

[0085] In a fourteenth operating step 98, each of the reconstructed adapted channel values 84 is modified at the receiver end by means of the receiver-end gain factor 96 allocated in each case to form a reconstructed channel value 100 and combined with the reconstructed unadapted channel value 86 to form a reconstructed output signal 102, which thus, with exception of noise introduced due to quantization, corresponds to the current channel values 40 which are present at the transmitter 18. In this context, a third noise level 104 is present due to the quantization which noise level is different with each of the channels 36. Thus, the third noise level 104 is in each case below the reconstructed channel value 100 or the reconstructed unadapted channel value 86, respectively, which is why an audio quality is improved. When the method 26 is carried out again, the reconstructed output signal 102 is utilized at least partially as the reconstructed preceding channel values 48. In a subsequent fifteenth operating step 106, the reconstructed output signal 102 is transferred into the time domain and output by means of the loudspeaker 14.

[0086] Furthermore, a sixteenth operating step 108 is carried out at the transmitter 18 in which, by means of the transmission value 76 and the gain factors 62, channel values 110 reconstructed at the transmitter end and an unadapted channel value 112 reconstructed at the transmitter end are generated which correspond to the reconstructed channel values 100 and the reconstructed unadapted channel value 86, respectively. In other words, the reconstructed output signal 102 is also generated at the transmitter 18. The channel values 110 reconstructed at the transmitter end and the unadapted channel value 112 reconstructed at the transmitter end are utilized as the channel values 44 preceding in time in the case of a transmission following in time. In this way, any deviation which is present due to the spherically logarithmic quantization in the reconstructed output signal 102 is also present at the receiver 18 which is why a deviation is reduced in the case of a subsequent transmission.

[0087] The invention is not restricted to the exemplary embodiment described above. Instead, other variants of the invention can also be derived therefrom by the expert without departing from the subject matter of the invention. In particular, all individual features described in conjunction with the exemplary embodiment can also be combined with one another in other ways without departing from the subject matter of the invention.

[0088] The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: [0089] 2 Hearing device system [0090] 4 Hearing aid [0091] 6 Housing [0092] 8 Microphone [0093] 10 Sound transducer [0094] 12 Signal processing unit [0095] 14 Loudspeaker [0096] 16 Audio signal [0097] 18 Transmitter [0098] 20 Receiver [0099] 22 Data signal [0100] 24 Communication facility [0101] 26 Method [0102] 28 First operating step [0103] 30 Second operating step [0104] 32 Input signal [0105] 34 Time window [0106] 36 Frequency channel [0107] 38 Frequency-pass filter [0108] 40 Current channel value [0109] 42 Third operating step [0110] 44 Channel values preceding in time [0111] 46 Fourth operating step [0112] 48 Reconstructed preceding channel values [0113] 50 First noise level [0114] 52 Fifth operating step [0115] 54 Prognostic value [0116] 56 Sixth operating step [0117] 58 Reference value [0118] 60 Seventh operating step [0119] 62 Gain factor [0120] 64 Difference [0121] 68 Eighth operating step [0122] 70 Adapted channel value [0123] 72 Adapted data record [0124] 74 Ninth operating step [0125] 76 Transmission value [0126] 78 Second noise level [0127] 80 Tenth operating step [0128] 82 Reconstructed adapted data record [0129] 84 Reconstructed adapted channel value [0130] 86 Reconstructed unadapted channel value [0131] 88 Eleventh operating step [0132] 90 Receiver-end prognostic value [0133] 92 Twelfth operating step [0134] 94 Thirteenth operating step [0135] 96 Receiver-end gain factor [0136] 98 Fourteenth operating step [0137] 100 Reconstructed channel value [0138] 102 Reconstructed output signal [0139] 104 Third noise level [0140] 106 Fifteenth operating step [0141] 108 Sixteenth operating step [0142] 110 Transmitter-end reconstructed channel value [0143] 112 Transmitter-end reconstructed unadapted channel value