EP3240307A1 - Method for transmitting an audio signal - Google Patents

Abstract

The invention relates to a method (26) for transmitting an audio signal (16) from a transmitter (18) to a receiver (20) and a hearing aid (4), in particular a hearing aid, having a communication device (24) for transmitting and / or Receiving an audio signal (16) according to such a method (26) is provided and set up. The invention further relates to a hearing aid system (2) with two hearing aids (4), which is provided and arranged to transmit audio signals (16) between the two hearing aids (4) by means of their communication devices (24) according to such a method.

Description

The invention relates to a method for transmitting an audio signal from a transmitter to a receiver. The invention further relates to a hearing aid and a hearing aid system with two such hearing aids. The hearing aid is preferably a hearing aid.

Persons suffering from a reduction in hearing usually use a hearing aid. In this case, an ambient sound is usually detected by means of an electromechanical sound transducer. The detected electrical signals are processed by means of an amplifier circuit and introduced by means of another electromechanical transducer in the ear canal of the person. Different types of hearing aids are known. The so-called "behind-the-ear devices" are worn between the skull and the auricle. The introduction of the amplified sound signal into the ear canal takes place here by means of a sound tube. Another common embodiment of a hearing aid is an "in-ear device" in which the hearing aid itself is inserted into the ear canal. Consequently, the auditory canal is at least partially closed by means of this hearing aid, so that no further sound - or only to a greatly reduced extent sound - can penetrate into the auditory canal, apart from the sound signals generated by the hearing aid.

If the person suffers from a hearing impairment in both ears, a hearing aid system with two such hearing aid is used. Here, each of the ears is assigned to one of the hearing aids. In order to allow the person a spatial hearing, it is necessary that the recorded with one of the hearing aids audio signals to each other hearing aid to provide. On the one hand, this requires transmission with only a comparatively small time offset. On the other hand, the head of the person acts as an attenuation, which is why the transmission rate between the hearing aids is limited. In addition, because of the limited energy storage of hearing aids and the otherwise excessive burden on the person a transmission power limited.

The invention has for its object to provide a particularly suitable method for transmitting an audio signal from a transmitter to a receiver and a particularly suitable hearing aid and a particularly suitable hearing aid system with two hearing aids, in particular an audio quality is improved, and preferably reduces a transmission rate is.

According to the invention, this object is achieved with regard to the method by the features of claim 1 and with regard to the hearing device by the features of claim 14 and with respect to the hearing aid system by the features of claim 15. Advantageous developments and refinements are the subject of the respective subclaims.

The method is for transmitting an audio signal from a transmitter to a receiver, wherein the transmitter or the receiver is preferably a component of a hearing device. The respectively remaining element, that is to say the transmitter or the receiver, is suitably a component of a further component of a hearing device system having the hearing device.

For example, the hearing aid is a headphone or includes a headphone. However, the hearing aid is particularly preferably a hearing aid. The hearing aid is used to support a person suffering from a reduction in hearing. In other words, the hearing aid is a medical device by means of which, for example, a partial hearing loss is compensated. The hearing aid is, for example, a "receiver-in-the-canal" hearing aid (RIC), an in-the-ear hearing aid such as an in-the-ear hearing aid, an in-the-ear -canal "- hearing aid (ITC) or a" complete-in-canal "hearing aid (CIC), a pair of hearing glasses, a pocket hearing aid, a bone conduction hearing aid or an implant. The hearing aid device is particularly preferably a behind-the-ear hearing aid device ("behind-the-ear" hearing aid device) which is worn behind an auricle.

The method provides that, at the transmitter end, an input signal corresponding to the audio signal is temporally divided into time windows, wherein the length of the time windows is preferably the same. The length of the time window is, for example, between 0.5 ms and 2 ms and in particular equal to 1 ms. The input signal is preferably the audio signal or in part thereof. For example, the audio signal is decomposed into different input signals, each input signal being respectively divided into different time slots. The time windows, for example their length, differ in particular with different input signals. For a given time window, the input signal is divided on the transmitter side into a number of channels. The channels here are frequency channels, for example. On the transmitter side, each frequency channel is assigned a current channel value. The current channel value is, for example, an amplitude and / or a phase or a signal level. In particular, the current channel value is a complex value and has a real and an imaginary part.

On the sender side, a number of forecast values for the current channel values are created based on previous channel values, whereby each of the current channel values is assigned to one of the forecast values. For example, the creation takes place in such a way that a difference between the respective forecast value and the assigned current channel value is as small as possible. At least, however, each of the forecast values is uniquely associated with one of the current channel values. In other words, just as many forecast values are created as there are current channel values. The previous channel values were assigned to a temporally preceding time window, for example the temporally directly preceding time window. In other words, a temporally preceding time window has already been divided into the number of channels, and each of these channels has just been assigned a previous channel value. For example, if the method is executed the first time, the initialization will be for example the value zero (0) is used for all previous channel values. As soon as a second time window is present for the first time, for example, the preceding channel values are assigned to the temporally first time window and the current channel values are assigned to the subsequent time window. For example, a number of temporally preceding channel values are used to generate the prognosis values, wherein, for example, for each of the prognosis values a number of preceding channel values are used, which are assigned to the same temporally preceding time window. Alternatively or in combination with this, for each of the forecast values a number of preceding channel values are used, which are assigned to different chronologically preceding time windows.

The transmitter side, a reference value is determined, wherein the reference value has a certain property, and for example, does not deviate from a certain, predetermined value or only to a small extent. Alternatively, the reference value deviates least from the determined, predetermined value. Furthermore, at the transmitter end, a prediction value is assigned a gain factor, which is determined on the basis of the reference value. The current channel value assigned to this forecast value is modified by means of the amplification factor to a matched channel value. In summary, therefore, one of the prediction values is assigned an amplification factor, and the amplification factor is used to modify the current channel value associated with the same prediction value to the adjusted channel value. For example, the current channel value is multiplied by the gain factor, or else the gain factor is added to the assigned current channel value to produce the adjusted channel value. If the current channel value is, for example, a complex value, the amplification factor is preferably applied to both the real and the imaginary component, ie both parts are modified by means of the same amplification factor. In summary, the current channel value is used as an argument of a function that has at least one parameter as the gain factor. The result of the function is the adjusted channel value.

On the sender side, the adjusted channel value is assigned to a customized data record. As a result, the customized record has the adjusted channel value. For example, the adjusted data set has further values, wherein the adjusted data set preferably has the same number of values as current channel values. A transmission value corresponding to the adapted data record is transmitted from the transmitter to the receiver, wherein the transmission value is expediently first created on the transmitter side on the basis of the adapted data record. The transmission value preferably has a lower dimensionality, or at least the same dimensionality, as the adapted data record, and is for example a one-dimensional value.

On the receiver side, a reconstructed adapted data record is created on the basis of the transmission value, which corresponds to the adapted data set present on the transmitter side. In particular, the inverse function for generating the transmission value is executed on the basis of the adapted data record. The reconstructed adjusted data set created in this way therefore essentially corresponds to the adapted data set on the transmitter side, differences preferably being present only on the basis of the generation of the transmission value. In particular, if the function to create the transmission value were applied to the reconstructed fitted data set, the transmission value would be obtained again. The reconstructed data set thus has a reconstructed adjusted channel value corresponding to the adjusted channel value, and in particular equal to the adjusted channel value.

Furthermore, on the receiver side, a number of receiver-side prediction values are created on the basis of reconstructed preceding channel values, the reconstructed preceding channel values corresponding, in particular, to the preceding channel values present on the transmitter side and suitably corresponding thereto. For example, the receiver-side forecast values are created using the same calculation rule as the forecast values that are available on the transmitter side. The reconstructed previous channel values are expediently reconstructed in a previous execution of the method and are in particular assigned to a chronologically preceding window, preferably the same temporally preceding time window, to which the channel values preceding the transmitter are assigned. For example, the first time the method is executed, it is assigned zero (0) to the reconstructed previous channel values.

In particular, the number of receiver-side forecast values corresponds to the number of forecast values that are present on the transmitter side. The reconstructed adjusted channel value is assigned to one of the receiver-side forecast values. In particular, the reconstructed adjusted channel value is assigned the receiver-side prediction value which was created on the basis of the same data as the prediction value assigned to the adapted channel value present on the transmitter side. Furthermore, a receiver-side reference value is determined on the receiver side, wherein the same procedure is used to determine the receiver-side reference value as for determining the reference value present on the transmitter side.

Furthermore, a receiver-side amplification factor is allocated to the receiver on the reconstructed adjusted channel value. For this purpose, the receiver-side gain factor is first assigned to the receiver-side prediction value assigned to the reconstructed adjusted channel value, and the receiver-side amplification factor is assigned to the adjusted channel value via the latter. In addition, on the receiver side, the reconstructed adjusted channel value is modified to a reconstructed channel value by means of the receiver-side amplification factor. In this case, in particular, an inverse function is performed for the function by means of which the current channel value present on the transmitter side is changed to the adapted channel value. In other words, the adjusted channel value is divided by the receiver-side amplification factor or the receiver-side amplification factor is subtracted from the reconstructed adjusted channel value. In other words, the reverse operation is used. Alternatively, the same calculation rule is used, but the receiver-side gain factor is the inverse element. In summary, the reconstructed channel value corresponds to the current channel value to which the gain factor is assigned on the transmitter side, and in particular the two channel values correspond, any differences preferably being present only due to the generation of the transmission value.

On the receiver side, the reconstructed channel value is added / summarized to a reconstructed output signal. In particular, further values of the reconstructed adjusted data record or values created on the basis of the reconstructed adapted data record are combined / added to the reconstructed output signal. In particular, the reconstructed output signal corresponds to the input signal / the entirety of the current channel values divided into the channels. For example, at the receiver end, the reconstructed output signal is further processed and the individual channels are combined and, for example, transferred to the time domain, provided that the channels correspond to individual frequencies. For example, when the method is executed again, the channel values of the reconstructed output signal are used as reconstructed previous channel values, and based on this, at least the receiver-side prediction values are created. In particular, the method is executed again after the expiry of the specific time window.

Due to the adaptation of the current channel value by means of the amplification factor, noise introduced as a result of the generation of the transmission value can be appropriately divided between the current channel values or reconstructed channel values, so that an audio quality is increased. Due to the use of the transmission value, a data amount to be transmitted is reduced. Since the gain factors are detected on both the receiver and transmitter sides, it is not necessary to transmit this value, which reduces a transmission transmission rate required.

For example, the reference value is assigned to a specific current channel value and / or one of the forecast values, wherein in particular no adaptation of this current channel value takes place by means of an amplification factor, if this current channel value is assigned to the adapted data record.

Appropriately, the receiver-side reference value is assigned to one of the receiver-side forecast values. For example, the reference value used is a fixed value (for example, 0 dB), the minimum of the forecast values, or the forecast value associated with a particular channel. Particularly preferably, however, the reference value used is the maximum of the forecast values. In other words, the largest of the forecast values is determined, both on the sender side, and in particular on the receiver side. Expediently, the current channel value to which the maximum of the prognosis values is assigned is assigned to the adapted dataset at the transmitter side, and the reconstructed adapted dataset with the reconstructed adapted channel value corresponding to the adapted channel value and with a reconstructed unadjusted dataset is based on the transmission value Channel value that corresponds to the current channel value associated with the maximum of the forecast values. On the receiver side, the reconstructed channel value and the reconstructed unadjusted channel value are combined to form the reconstructed output signal. Due to the use of the maximum, the current channel value associated with the largest of the forecast values, and most likely also the largest of the current channel values, is not changed, whereas at least one of the remaining current channel values is changed. In particular, the amplification factor is selected such that the deviation between the assigned prognosis value and the reference value would be greater than a deviation between the reference value and the prognosis value modified by means of the amplification factor. Consequently, a deviation between the adjusted channel value and the current channel value assigned to the reference value is also most likely to be reduced, so that any noise introduced when establishing the transmission value is present only to a reduced extent in the reconstructed channel value. Suitably, the reconstructed unadjusted channel value present on the receiver side is not changed.

Preferably, the amplification factor is selected such that a deviation between the prediction value associated therewith and the reference value is greater than a deviation between the reference value and that by means of the amplification factor modified forecast value would be. In other words, if the amplification factor is applied to the prognosis value to which the amplification factor is assigned, the deviation between the reference value and the prognosis value just changed would be reduced. Consequently, if a deviation between the forecast values and the current channel values is comparatively small, a deviation between the adjusted channel value and the current channel value to which the maximum of the forecast values is assigned is therefore also reduced. If, due to the generation of the transmission value, noise is introduced which is dependent on the current channel value to which the reference value is assigned, the noise which the reconstructed channel value has is thus reduced due to the use of the amplification factor and of the receiver-side amplification factor.

Conveniently, the reconstructed unadjusted channel value is assigned to the same channel as the current channel value to which the reference value is assigned. For example, the reconstructed channel value is assigned to the same channel that is assigned to the current channel value at the transmitter end, to which the amplification factor is assigned. The predicted value of the preceding channel value assigned to the same channel is preferably used. In other words, the respective previous channel value is used as the prognosis value for each of the current channel values. In this way, an effort to create the forecast values is reduced. If the input signal thus has comparatively small fluctuations, a deviation between the prediction value and the respective assigned current channel value is comparatively small. In particular, the reconstructed preceding channel values are also used as receiver-side prediction values, the allocation to the respective channels also being taken into account here.

In an alternative to this, a linear prediction is used to generate the prognosis values or the receiver-side prediction values, for example using a number of chronologically preceding channel values. In other words, each of the forecast values is by means of a linear combination created, for example, a number of temporally preceding channel values is used.

Suitably, the receiver-side reference value determines which of the values of the fitted data set is the reconstructed unadjusted channel value. First, the receiver-side forecast values are created and assigned to each of the values of the reconstructed adjusted data record of one of the receiver-side forecast values. The value of the reconstructed matched data set to which the receiver-side reference value is assigned is used as the reconstructed unadjusted channel value. Alternatively, each value of the reconstructed adjusted data set is assigned an index or the like, on the basis of which an assignment to the respective channels takes place.

Particularly preferably, the amplification factor is created on the basis of the prognosis value to which the amplification factor is assigned. Suitably, the receiver-side gain factor is constructed from the receiver-side forecast value to which the reconstructed adjusted channel value is assigned. In this way, it is not necessary to transmit the amplification factors or values corresponding thereto between the receiver and the transmitter, which further reduces an amount of data to be transmitted. In particular, the same calculation rule is used to generate the amplification factor or the receiver-side amplification factor.

Suitably, the gain factor is calculated from the difference between the reference value and the forecast value. In other words, first the difference between the reference value and the prediction value is created, to which the amplification factor is to be assigned. Based on this difference, the amplification factor is determined. In particular, the amplification factor is the difference multiplied, for example, by a factor, the factor being expediently chosen to be constant. In particular, on the receiver side, the difference between the receiver-side prediction value to which the reconstructed adjusted channel value is to be assigned, and the receiver-side Reference value determined, and the receiver-side gain factor is determined based on this difference. In particular, the receiver-side gain factor is the difference, which is multiplied by a factor, for example. In this way, the determination of the amplification factor is comparatively simple. In addition, in this way, an adaptation of the adapted channel value is such that a deviation from the current channel value assigned to the reference value is reduced. This also takes into account current changes in the input signal, which would not be the case, for example, given a fixed specification of the amplification factors.

In particular, a respective amplification factor is allocated to each of the other forecast values, and these are preferably adjusted in each case by means of the assigned amplification factor and assigned to the adapted data record. Thus, there is a number of reconstructed matched channel values on the receiver side, each of these being assigned a receiver-side gain factor, on the basis of which reconstructed channel values are created, which are combined to form the reconstructed output signal. In other words, all the current channel values, with the exception of the current channel value to which the reference value is assigned, are modified by means of the respective amplification factor, and the channel values adapted in this way are transmitted by means of the transmission value. On the receiver side, the reconstructed output signal is generated on the basis of the reconstructed adapted channel values as well as the amplification factors present on the receiver side, which thus corresponds in particular to the input signal. In this case, the adapted data record has only a single current channel value, namely the one to which the reference value is assigned. In particular, the receiver-side reference value is determined on the receiver side, so that it is comparatively easy to determine which of the values of the reconstructed adjusted data set should not be changed by an amplification factor.

The receiver-side prediction values and the prognosis values that are present on the transmitter side, as well as the amplification factor and the receiver-side amplification factor, are substantially simultaneously created. In this way, a time period used for transmitting the audio signal is reduced. In particular, a period of time between detection of the input signal and generation of the reconstructed output signal is shortened in this way.

The individual amplification factors and the individual receiver-side amplification factors preferably differ. These are expediently determined on the basis of the respective prognosis value as well as of the reference value or of the receiver-side prognosis value and of the receiver-side reference value, expediently on the basis of their difference. Suitably, the gain factor $${\mathrm{G}}_{\mathrm{i}}={\mathrm{w\Delta L}}_{\mathrm{i}}$$

Here, w is a constant factor and ΔL _i denotes the difference between the reference value and the i-th forecast value or the receiver-side reference value and the i-th receiver-side prediction value, where i denotes the respective channel to which the respective prognosis value or receiver-side prediction value is assigned is. In this way, substantially all current channel values are adjusted to an almost equal level with the current channel value to which the reference value is assigned. Thus, all values of the adjusted data set are substantially the same size, therefore any noise will be substantially equally divided among all reconstructed matched channel values and the reconstructed unadjusted channel value. Thus, after applying the receiver-side gain factors, the noise in the reconstructed channel values is less than in the reconstructed unadjusted channel value. In particular, provided the maximum is used as reference value, noise is therefore reduced for comparatively small current channel values, which improves audio quality.

For example, the input signal is divided into the frequency channels by means of a Fourier transformation. However, bandpass filters are particularly preferred used, which are preferably summarized in a filter bank. Alternatively or in combination with this, a difference between a predicted audio signal and the actual audio signal is used as input signal, for which purpose the audio signal is first divided into the channels or channels deviating therefrom, and the predicted audio signal is created by means of a linear prediction.

oder $$\hat{\mathbf{x}}\left(\mathrm{n}\right)={\displaystyle \sum _{\mathrm{i}=\mathrm{1}}^{\mathrm{N}}\mathbf{A}\mathbf{y}}\left(\mathrm{n}-\mathrm{i}\right)$$

ermittelt. x̂(n) bezeichnet hierbei die die Kanäle des prognostizierten Audiosignals. a_i bezeichnet einen Koeffizienten, A eine Koeffizientenmatrix und y die Gesamtheit der Werte, die zur Erstellung herangezogen werden, insbesondere die zeitlich vorhergehenden Wert des in die Kanäle aufgeteilten Audiosignals. Der Erstellungszeitpunkt ist hierbei n - i, und die verwendete Anzahl ist N. Eine Art von linearer Vorhersage ist beispielsweise in " Benesty, J., Chen, J., & Huang, Y. (Arden). (2008). Linear Prediction. In J. Benesty, M. M. Sondhi, & Y. (Arden) Huang (Eds.), Springer Handbook of Speech Processing (pp. 111-125) Springer Verlag " offenbart, insbesondere in Kapitel 7.2 (Seite 112 - 113), insbesondere Formel 7.6, sowie insbesondere in Kapitel 7.9 (Seite 120 -124), insbesondere Formel 7.108. Als Eingangssignal wird Beispielsweise die Gesamtheit der Differenz zwischen dem jeweiligen x̂(n) und dem korrespondierenden y(n) herangezogen.In summary, the predicted audio signal is calculated using the formula $$\hat{\mathbf{x}}\left(\mathrm{n}\right)={\displaystyle \underset{\mathrm{i}=\mathrm{1}}{\overset{\mathrm{N}}{\Sigma }}{\mathrm{a}}_{\mathrm{i}}\mathrm{y}}\left(\mathrm{n}-\mathrm{i}\right)$$

or $$\hat{\mathbf{x}}\left(\mathrm{n}\right)={\displaystyle \underset{\mathrm{i}=\mathrm{1}}{\overset{\mathrm{N}}{\Sigma }}\mathbf{A}\mathbf{y}}\left(\mathrm{n}-\mathrm{i}\right)$$

determined. x (n) denotes the channels of the predicted audio signal. a _i denotes a coefficient, A a coefficient matrix and y the totality of the values used for the creation, in particular the temporally preceding value of the audio signal divided into the channels. The creation time here is n - i, and the number used is N. One kind of linear prediction is, for example, in " Benesty, J., Chen, J., & Huang, Y. (Arden). (2008). Linear Prediction. J. Benesty, MM Sondhi, & Y. (Arden) Huang (Eds.), Springer Handbook of Speech Processing (pp. 111-125) Springer Verlag , especially in chapter 7.2 (pages 112-113), in particular formula 7.6, and in particular in chapter 7.9 (pages 120-124), in particular formula 7.108 As an input signal, for example, the totality of the difference between the respective x (n) and the corresponding y (n) used.

For example, the transfer value is created by quantizing the adjusted record. In this case, the adapted data record is assigned the transmission value, which expediently has only a discrete number of different ones Can accept values. In other words, the transmission value is a discrete value.

Preferably, a transmitter-side reconstructed channel value and a transmitter-side reconstructed unadjusted channel value are generated on the transmitter side on the basis of the transmission value and on the basis of the amplification factor. The transmitter-side reconstructed channel value corresponds to the reconstructed channel value present on the receiver side, and the transmitter-side reconstructed unadjusted channel value corresponds to the reconstructed unadjusted channel value present on the receiver side. The transmitter-side reconstructed channel value and the transmitter-side reconstructed unadjusted channel value are present on the transmitter side.

In other words, based on the transmission value and the amplification factor, the reconstructed output signal is also generated on the transmitter side, which may deviate slightly from the input signal due to the quantization and the induced noise introduced as a result. In the case of a subsequent transmission, the transmitter-side reconstructed channel value and the transmitter-side reconstructed unadjusted channel value are used as the temporally preceding channel values or at least as a part thereof. In this way, deviations between the output signal and the input signal due to the quantization are taken into account in the generation of the prediction values, and therefore a maximum deviation between the input signal and the reconstructed output signal remains low even with a repeated execution of the method, and thus a high transmission quality of the audio signal is present.

Suitably scalar quantization is used. More preferably, the quantization is a vector quantization. Suitably, a so-called gain-shape vector quantization is used. The quantized signal is hereby divided into the signal shape / vector shape (shape) and a scaling factor (gain). A particularly suitable form of gain-shape vector quantization represents the logarithmic vector quantization, in particular the (spherical) logarithmic vector quantization. In this case, possible signal forms / vector shapes are points on a (potentially) high-dimensional unit sphere (ie with radius 1). The scaling factor is quantized logarithmically, for example, with the known A-law. Waveforms / vector shapes may also be other shapes such as (high dimensional) pyramids or cubes. For example, spherical-logarithmic vector quantization is " B. Matschkal and JB Huber, "Spherical Logarithmic Quantization", IEEE Trans. Audio, Speech, and Language Processing, vol. 18, pp. 126-140, Jan. 2010 in particular from Chapter III, an example of which is disclosed in Chapter IV, in particular in 8 and 9 ,

The hearing device has a communication device for transmitting and / or receiving an audio signal. For this purpose, the communication device comprises a transmitter or a receiver. The communication device is suitable as well as provided and set up to carry out a method for transmitting an audio signal from the transmitter or to the receiver. In this case, the method provides that, on the transmitter side, an input signal corresponding to the audio signal for a specific time window is divided into a number of channels, and that a current channel value is assigned to each channel on the transmitter side. Furthermore, on the transmitter side, a number of prediction values are created on the transmitter side based on preceding channel values which are assigned to a temporally preceding time window, wherein one of the prognosis values is assigned to each current channel value, and a reference value is determined on the transmitter side. On the transmitter side, one of the prognosis values is assigned an amplification factor determined on the basis of the reference value, and the current channel value assigned to this prognosis value is changed to a matched channel value by means of the amplification factor. In a further step, the adapted channel value is assigned to a matched data record on the sender side. A transmission value corresponding to the adjusted data record is transmitted from the sender to the receiver.

On the receiver side, based on the transmission value, a reconstructed adapted data record with a reconstructed adapted channel value, which is assigned to the adjusted channel value created. On the basis of reconstructed previous channel values, which are assigned in particular to the temporally preceding time window, a number of receiver-side prediction values are created on the receiver side, wherein the reconstructed adjusted channel value is assigned to one of the receiver-side prediction values. Furthermore, a receiver-side reference value, in particular the receiver-side prediction values, is determined on the receiver side, and a receiver-side amplification factor is assigned to the reconstructed adjusted channel value on the basis of the associated receiver-side prediction value, which is preferably determined on the basis of the receiver-side reference value. On the receiver side, the reconstructed adjusted channel value is modified by means of the receiver-side amplification factor to a reconstructed channel value. In a further step, the reconstructed channel value is combined to a reconstructed output signal on the receiver side.

If the communication device only comprises the transmitter, in this case in particular only the transmitter-side working steps and a work step for transmitting the deviations are carried out. If the communication device only has the receiver, in particular only the receiver-side working steps and a work step for receiving the deviations are carried out. Conveniently, the transmission is wireless, such as inductive or wireless.

The hearing device preferably comprises a sensor, by means of which an audio signal is detected during operation. The sensor is preferably an electromechanical transducer, such as a microphone. For example, the input signal is the audio signal, or the input signal is created based on the audio signal. For example, the input signal is a part of the audio signal, or corresponds to a certain frequency range of the audio signal. To generate the input signal from the audio signal, the hearing device comprises, for example, a signal processing unit and / or filter. The hearing aid preferably comprises an amplifier circuit by means of which the audio signal / output signal / reconstructed output signal can be amplified. Preferably, the hearing aid comprises an actuator, by means of of which a sound signal is produced, such as a loudspeaker, and which is suitable for outputting the output signal or the reconstructed output signal, and is provided and suitable, for example.

For example, the hearing aid is a headphone or includes a headphone. However, the hearing aid is particularly preferably a hearing aid. The hearing aid is used to support a person suffering from a reduction in hearing. In other words, the hearing aid is a medical device by means of which, for example, a partial hearing loss is compensated. The hearing aid is, for example, a "receiver-in-the-canal" hearing aid (RIC), an in-the-ear hearing aid such as an in-the-ear hearing aid, an in-the-ear -canal "- a hearing aid (ITC) or a complete-in-canal hearing aid (CIC), a pair of hearing glasses, a pocket hearing aid, a bone conduction hearing aid or an implant. The hearing aid device is particularly preferably a behind-the-ear hearing aid device ("behind-the-ear" hearing aid device) which is worn behind an auricle.

The hearing aid is in particular provided and adapted to be worn on the human body. In other words, the hearing aid preferably comprises a holding device, by means of which an attachment to the human body is possible. If the hearing device is a hearing aid device, the hearing device is provided and set up, for example, to be arranged behind the ear or within an auditory canal. In particular, the hearing aid is wireless and provided and arranged to be at least partially inserted into an ear canal. For example, the hearing aid is a component of a hearing aid system which comprises a further hearing aid or a further device, such as a directional microphone or another device having a microphone. In this case, the device preferably comprises the transmitter and the hearing device the receiver, and the transmission of the audio signal between the transmitter and the receiver is carried out according to the method.

The hearing device system preferably comprises two hearing aids, each of which has a communication device that is capable of transmitting and / or receiving a Audio signals are provided and set up according to the above method. In this case, the hearing device system is suitable as well as provided and set up to transmit audio signals between the two hearing aids by means of their respective communication devices, wherein the above method is performed. In particular, each of the communication devices each has a transmitter and a receiver, and the audio signals are transmitted between the two communication devices, at least from one of the hearing aids to the remaining one. Conveniently, the transmission is wireless, such as inductive or wireless.

The hearing aid system is particularly preferably a hearing aid system. The hearing aid system is used to support a person suffering from a reduction in hearing. In other words, the hearing aid system is a medical device by means of which, for example, a partial hearing loss is compensated. The hearing aid system expediently comprises a behind-the-ear hearing aid that is worn behind an auricle, a "receiver-in-the-canal" hearing aid (RIC), an in-the-ear hearing aid, such as an in-the-ear hearing aid, an in-the-canal hearing aid (ITC) or a complete-in-canal hearing aid (CIC), a pair of hearing-glasses, a pocket-hearing aid, a bone conduction hearing aid or but an implant. The hearing aid system is in particular provided and adapted to be worn on the human body. In other words, the hearing aid system preferably comprises a holding device, by means of which an attachment to the human body is made possible. If the hearing aid system is a hearing aid system, at least one of the hearing aids is provided and set up, for example, to be arranged behind the ear or within an auditory canal. In particular, the hearing aid system is wireless and designed and arranged to be at least partially inserted into an ear canal. Particularly preferably, the hearing device system comprises an energy store, by means of which a power supply is provided.

In summary, the invention provides in particular that the audio signal is split into frequency channels. This is followed by the formation of a vector a set of channel values and one of a reference value and the application of a gain factor to all elements of the vector, the gain factors preferably differing. If the reference value is a current channel value, preferably no gain factor is applied to it. The gain factor is calculated as a function of previous (past, "reconstructed") channel values and therefore the use of information that is present at both the transmitter and the receiver side. For example, a previous channel value is understood to be a quantized channel value or a reconstructed channel value in the sense of a predictive coding (that is to say as the sum of deviation and prognosis). The thus adapted channel values are vector quantized. Subsequently, the inverse amplification factor is applied to the now quantized values.

The further developments and advantages described in connection with the method are also to be transferred analogously to the hearing device or the hearing device system and vice versa.

Fig. 1

schematisch ein Hörgerätesystem mit zwei Hörgeräten,

Fig. 2

ein Verfahren zum Übertragen eines Audiosignals zwischen den beiden Hörgeräten,

Fig. 3

ein zu dem Audiosignal korrespondierendes Eingangssignal,

Fig. 4

das in eine Anzahl von Kanälen aufgeteilte Eingangssignal,

Fig. 5

aktuelle Kanalwerte,

Fig. 6

Prognosewerte,

Fig. 7

einen angepassten Datensatz,

Fig. 8

schematisch ausschnittsweise das Hörgerätesystem, und

Fig. 9

einen rekonstruierten angepassten Datensatz und ein rekonstruiertes Ausgangssignal.

An embodiment of the invention will be explained in more detail with reference to a drawing. Show:

Fig. 1

schematically a hearing aid system with two hearing aids,

Fig. 2

a method for transmitting an audio signal between the two hearing aids,

Fig. 3

an input signal corresponding to the audio signal,

Fig. 4

the input signal divided into a number of channels,

Fig. 5

current channel values,

Fig. 6

Forecast values

Fig. 7

a customized record,

Fig. 8

schematically a partial view of the hearing aid system, and

Fig. 9

a reconstructed adjusted data set and a reconstructed output signal.

Corresponding parts are provided in all figures with the same reference numerals.

In Fig. 1 a hearing aid system 2 is shown with two identical hearing aids 4, which are provided and adapted to be worn behind an ear of a user. In other words, it is in each case a behind-the-ear hearing aid device ("behind-the-ear" hearing aid device), which has a sound tube, not shown, which is inserted into the ear. Each hearing aid device 4 comprises a housing 6, which is made of a plastic. Within the housing 6, a microphone 8 with two electromechanical transducers 10 is arranged. By means of the two electromechanical sound transducers 10, it is possible to change a directional characteristic of the microphone 8 by changing a temporal offset between the acoustic signals detected by the respective electromechanical sound transducer 10. The two electromechanical sound transducers 10 are signal-coupled 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 electrical and / or electronic components.

Furthermore, a loudspeaker 14 is signal-wise coupled to the signal processing unit 12, by means of which the audio signals 16 received by the microphones 8 and / or processed by the signal processing unit 12 are output as sound signals. These sound signals are directed into the ear of a user of the hearing aid system 2 by means of the sound tube not shown near.

Each of the hearing aid devices 4 also has a transmitter 18 and a receiver 20, by means of which an exchange of data signals 22 between the two hearing aids 4 takes place. The exchange is wireless, for example by radio or inductively. The signal processing unit 12, the transmitter 18 and the receiver 20 in each case together essentially form a communication device 24. Due to the exchange of the data signals 22, it is possible to give the wearer of the hearing aid system 2 a spatial sense of hearing. In summary, the hearing aid system 2 is configured binaurally.

In Fig. 2 a method 26 is shown, according to which the audio signals 16 are transmitted between the two hearing aids 4 by means of their respective communication device 24. In a first step 28, the audio signal 16 is received by means of one of the hearing aid devices 4. In a subsequent second step 30, an input signal 32 is created from this, which consequently corresponds to the audio signal 16 and corresponds to the input signal 32 in FIG FIG. 3 is shown by way of example. For this purpose, the audio signal 16 is filtered in particular. Furthermore, the input signal 32 is subdivided into time windows 34, which have the same time length and which is, for example, equal to one millisecond. Once the last temporal window 34 is completed, this time window 34 is divided into a number of channels 36, such as in FIG FIG. 4 shown. The channels 36 are frequency channels and for dividing the input signal 32 into the individual frequency channels 36, frequency-pass filters 38 are used which are present within the signal-processing unit 16. Furthermore, the input signal 32 comprises only the channels 36, whereas the audio signal 16 has the channels 36 and still further frequency channels. Each of the frequency channels 36 is assigned a particular current channel value 40. In summary, in the second step 30, the input signal 32 is divided into the individual frequency channels 36 and discretized by means of the assignment of the current channel value 40.

Furthermore, after execution of the first working step 16, a third operation 42 is carried out on the transmitter 18 side, in which channel values 44 preceding in time are filled. These have been determined, for example, in a previous run of the method 26 or, if the method 26 has not yet been carried out, standard values are used for this, such as zero (0). Also on the receiver 20 side, a fourth step 46 is performed, in which reconstructed previous channel values 48 are determined. These correspond to the temporally preceding channel values 44 and are determined in the same way as the temporally preceding channel values 44.

In Fig. 5 the current channel values 40 are shown, each of which is assigned to one channel 36 each. One of the current values 40 is comparatively large. Applying a spherical logarithmic quantization to the input signal 32 would introduce a first noise level 50 due to the increased current channel value 40, which is largely larger than the remaining current channel values 40, so that they would be excessively corrupted.

In a fifth step 52, therefore, a number of prediction values 54 are generated on the transmitter side based on the preceding channel values 44, wherein each of the prediction values 54 is assigned to one of the channels 36 and thus also to one of the current channel values 40, as in FIG Fig. 6 shown. The prediction value 54 used is the temporally preceding channel value 44 allocated to the same channel 36.

In a subsequent sixth step 56, a reference value 58 of the prognosis values 54 is determined, the reference value 58 being taken as the maximum of the prognosis values 54. In other words, the largest of the prediction values 54, and thus the largest of the preceding channel values 44, is determined.

ermittelt, wobei w einen beliebigen Faktor zwischen null (0) und eins (1), beispielsweise 0,5 bezeichnet. Gi ist der Verstärkungsfaktor 62, der dem Kanal 36 mit dem Index i zugeordnet ist. ΔL_i bezeichnet die Differenz 64 zwischen dem Referenzwert 58 und dem Prognosewert 54, der dem Kanal 36 mit dem Index i zugeordnet ist. Folglich unterscheiden sich sämtliche der Verstärkungsfaktoren 62 und der jeweilige Verstärkungsfaktor 62 ist anhand des jeweils zugeordneten Prognosewerts 54 erstellt, dem der Verstärkungsfaktor 62 zugeordnet ist.The remaining forecast values 54 are each assigned a gain factor 62 in a seventh step 60, with the gain factors 62 differing. Thus, the channels 36 for the time window 34 are assigned gain factors 62, each of the gain factors 62 being associated with exactly one of the current channel values 40, with the exception of the current channel value 40 to which the reference value 58 is assigned. Each of the gain factors 62 is hereby given the formula $${\mathrm{G}}_{\mathrm{i}}={\mathrm{w\Delta L}}_{\mathrm{i}}$$

where w denotes any factor between zero (0) and one (1), for example 0.5. Gi is the gain factor 62, which is the channel 36 associated with the index i. ΔL _i denotes the difference 64 between the reference value 58 and the prediction value 54 associated with the channel 36 with the index i. Consequently, all of the gain factors 62 differ and the respective gain factor 62 is created on the basis of the respective associated forecast value 54 to which the gain factor 62 is assigned.

In a subsequent eighth step 68, each of the current channel values 40 is modified by means of the amplification factor 54 which is assigned to the respective associated forecast value 54 and created on the basis of this. Thus, each of the current channel values 40, except for the current channel value 40 to which the reference value 58 is assigned, and thus to which none of the gain factors 62 are assigned, is changed to a matched channel value 70. The respective current channel value 40 is multiplied by the respectively assigned amplification factor 62, such as schematically in FIG Fig. 8 shown. Thus, the respective amplification factor 54 is chosen such that a deviation between the associated prognosis value 54 and the reference value 58 would be greater than a deviation between the reference value 58 and the prognosis value modified by means of the amplification factor 54. Since the current channel values 40 generally deviate only comparatively slightly from the respective temporally preceding channel value 44, the deviation between the current channel value 40, to which the reference value 58 is assigned, and the adapted channel values 70 is thus also reduced.

The adjusted channel values 70 and the current channel value 40 to which the reference value 58 is assigned are assigned to a matched data set 72, which is thus a vector having as many elements as present channel values 40 are present. In a ninth operation 74, the adjusted data set 72 is quantized by means of a spherical logarithmic quantization and a transmission value 76 is formed, which is consequently one-dimensional. In other words, the transmission value 76 is produced by means of quantization of the adapted data set 72, wherein the quantization used is the spherical logarithmic quantization. Due to the quantization, a second noise level 78 is introduced into the adjusted data set 72. The transmission value 76 is transmitted to the remaining hearing aid 4 as part of the data signal 22.

The transmission value 76 is received by means of the receiver 20 and a tenth operation 80 is carried out, in which the receiver uses the transmission value 76 to create a reconstructed adapted data set 82 which is stored in Fig. 9 is shown. This corresponds to the matched data set 72 except for any noise introduced due to quantization. In other words, the reconstructed matched data set 82 has a number of reconstructed matched channel values 84 corresponding to the number of matched channel values 70, each of the reconstructed matched Channel values 84 corresponds to one of the adapted channel values 70 and corresponds in particular to this. Furthermore, the reconstructed adjusted data set 82 has a reconstructed unadjusted channel value 86 corresponding to the current channel value 40 associated with the reference value 58 of the prediction values 54, and thus is essentially the only current channel value 40 that is substantially unchanged, except for quantization Transmitter 18 has been transmitted to the side of the receiver 20.

In an eleventh step 88, a number of receiver-side prediction values 90 are created on the receiver side based on the reconstructed preceding channel values 48, wherein the reconstructed adjusted channel values 84 and the reconstructed unadjusted channel value 86 are each assigned to one of the receiver-side prediction values 90. In a twelfth step 92, a maximum of the receiver-side prediction values 92 is determined, and in this way the reconstructed unadjusted channel value 86 is identified within all the values of the reconstructed adjusted data set 82. In a subsequent thirteenth operation 94, the receiver-side prediction values 90 and the receiver-side maximum value of the receiver-side prediction values 90 on the receiver-side amplification factors 96 are determined on the basis of the receiver-side prediction values 90. Each of the receiver-side gain factors 96 is assigned to one of the reconstructed matched channel values 84 and to the respective receiver-side prediction values 90. Because the reconstructed previous channel values 48 correspond substantially to the previous channel values 44, the prediction values 54 and the receiver-side prediction values 90 correspond to one another. For determining the receiver-side amplification factors 96, the same calculation rule is used as for determining the amplification factors 62 present on the transmitter 18 side. The receiver-side amplification factor 96, which corresponds to the transmitter-side amplification factor 62, is assigned to the same channel 36 here.

In summary, the eleventh, twelfth and thirteenth steps 88,92,94 essentially correspond to the fifth, sixth and seventh step 52, 56, 60, but different input data are used, namely once the temporally preceding channel values 44 and the other time the reconstructed preceding ones Channel values 48, which, however, are the same due to the fourth operation 46 and the third operation 42. Thus, each gain factor 62 is equal to the transmitter-side gain factor 96 associated with each same channel 36. Transmission of the amplification factor 96 from the transmitter 18 to the receiver 20 side is not required.

In a fourteenth step 98, each of the reconstructed matched channel values 84 is modified at the receiver side to a reconstructed channel value 100 by the respectively assigned receiver-side gain factor 96 and combined with the reconstructed unadjusted channel value 86 to form a reconstructed output signal 102 which, with the exception of noise due to quantization current channel values 40 present on the transmitter 18 side. Here, due to the quantization, a third noise level 104 is present, which is different for each of the channels 36. Thus, the third noise level 104 is below the reconstructed channel value 100 or the reconstructed unadjusted channel value 86, for which reason an audio quality is increased. Repeating the method 26, the reconstructed output signal 102 is at least partially used as the reconstructed previous channel values 48. In a subsequent fifteenth step 106 is the reconstructed Output signal 102 is transferred to the time domain and output by means of the loudspeaker 14.

Furthermore, a sixteenth step 108 is carried out on the part of the transmitter 18 in which the transmitter value 76 and the gain factors 62 are used to create transmitter-side reconstructed channel values 110 and a transmitter-end reconformed unadjusted channel value 112 corresponding to the reconstructed channel values 100 and the reconstructed unadjusted channel value 86, respectively correspond. In other words, the reconstructed output signal 102 is also created on the transmitter 18 side. The channel values 110 reconstructed on the transmitter side and the unadapted channel value 112 reconstructed on the transmitter side are used as the temporally preceding channel values 44 in the case of a temporally subsequent transmission. In this way, any deviation which is present in the reconstructed output signal 102 due to the spherical logarithmic quantization is also present on the side of the receiver 18, as a result of which a deviation is reduced in a subsequent transmission.

The invention is not limited to the embodiment described above. Rather, other variants of the invention can be derived therefrom by the person skilled in the art without departing from the subject matter of the invention. In particular, all the individual features described in connection with the exemplary embodiment can also be combined with each other in other ways, without departing from the subject matter of the invention.

LIST OF REFERENCE NUMBERS

2

Hearing aid system

4

hearing aid

6

casing

8th

microphone

10

transducer

12

Signal processing unit

14

speaker

16

audio signal

18

transmitter

20

receiver

22

data signal

24

communicator

26

method

28

first step

30

second step

32

input

34

Time window

36

frequency channel

38

Frequency pass filter

40

current channel value

42

third step

44

temporally preceding channel values

46

fourth step

48

reconstructed previous channel values

50

first noise level

52

fifth step

54

forecast value

56

sixth step

58

reference value

60

seventh step

62

gain

64

difference

68

eighth step

70

adjusted channel value

72

adapted record

74

ninth step

76

transfer value

78

second noise level

80

Tenth work step

82

reconstructed adjusted record

84

reconstructed adjusted channel value

86

reconstructed unadjusted channel value

88

eleventh step

90

receiver-side forecast value

92

Twelfth step

94

thirteenth work step

96

receiver-side gain factor

98

Fourteenth step

100

reconstructed channel value

102

reconstructed output signal

104

third noise level

106

fifteenth step

108

sixteenth step

110

transmitter-side reconstructed channel value

112

transmitter-side reconstructed unadjusted channel value

Claims (15)

Method (26) for transmitting an audio signal (16) from a transmitter (18) to a receiver (20), in which at the transmitter end, an input signal (32) corresponding to the audio signal (16) is divided into a number of channels (36) for a specific time window (34), each channel (36) is assigned a current channel value (40) at the transmitter end, - generating a number of forecast values (54) on the transmitter side based on preceding channel values (44) associated with a chronologically preceding time window (34), wherein each current channel value (40) is assigned to one of the forecast values (54), a reference value (58) is determined on the transmitter side, one of the prediction values (54) is assigned a gain factor (62) determined from the reference value (58), and the current channel value (40) assigned to this prediction value (54) is changed to a matched channel value (70) by means of the amplification factor (62) becomes, at the transmitter end, the adapted channel value (70) is assigned to a matched data record (72), a transmission value (76) corresponding to the adapted data record (72) is transmitted from the transmitter (18) to the receiver (20), on the receiver side, on the basis of the transmission value (76), a reconstructed adapted data record (82) having a reconstructed adapted channel value (84) which corresponds to the adapted channel value (44) is created, a number of receiver-side forecast values (90) are created on the receiver side on the basis of reconstructed preceding channel values (48), wherein the reconstructed adapted channel value (84) is assigned to one of the receiver-side prediction values (90), on the receiver side, a receiver-side amplification factor (96) is assigned to the reconstructed adapted channel value (84) on the basis of the associated receiver-side prediction value (90), on the receiver side, the reconstructed adjusted channel value (84) is modified to a reconstructed channel value (100) by means of the receiver-side amplification factor (96), and the receiver side, the reconstructed channel value (100) is added to a reconstructed output signal (102). Method (26) according to claim 1,
characterized,
the reference value (58) used is the maximum of the forecast values (54). Method (26) according to claim 2,
characterized, that the current channel value (40) to which the maximum (58) of the forecast values (54) is assigned is assigned to the adapted data record (72) on the transmitter side, - that at the receiver end, based on the transmission value (76), the reconstructed adjusted data set (82) with the reconstructed adjusted channel value (84) corresponding to the adjusted channel value (44) and with a reconstructed unadjusted channel value (86) corresponding to the maximum (58) the current channel value (40) associated with the forecast values (54) corresponds, is created, and - That the receiver side of the reconstructed channel value (100) and the reconstructed unadjusted channel value (86) are combined to the reconstructed output signal (102). Method (26) according to one of claims 1 to 3,
characterized,
in that the amplification factor (54) is selected such that a deviation between the prediction value (54) associated therewith and the reference value (58) would be greater than a deviation between the reference value (54) and the predicted value (54) modified by means of the gain factor (62). Method (26) according to one of claims 1 to 4,
characterized,
in that the preceding channel value (44) assigned to the same channel (36) is used as the prognosis value (54). Method (26) according to one of claims 1 to 5,
characterized,
in that the amplification factor (62) and the receiver-side amplification factor (96) are assigned on the basis of the prediction value (54) to which the amplification factor (62) is assigned, or on the receiver-side prediction value (90) assigned to the reconstructed adapted channel value (84), is created. Method (26) according to claim 6,
characterized,
that the gain factor is created by the difference (64) between the reference value (58) and the forecast value (54). Method (26) according to one of claims 1 to 7,
characterized,
a respective amplification factor (62) is allocated to each of the remaining forecast values (54), with the amplification factors (62) differing in particular. Method (26) according to one of claims 1 to 8,
characterized,
in that the division of the input signal (32) into the frequency channels (36) takes place by means of bandpass filters (38). Method (26) according to one of claims 1 to 9,
characterized,
that the transmission value (76) is created by means of quantization of the adjusted data set (72). Method (26) according to claim 10,
characterized,
that the transmitter side on the basis of the transmission value (76) and the gain (62) comprises a transmitter-side reconstructed channel value (110) can be created that corresponds to the reconstructed channel value (100), and as one of the temporally preceding channel values at a time subsequent transmission (44) be used. Method (26) according to claim 10 or 11,
characterized,
that quantization is done by vector quantization. Method (26) according to one of claims 10 to 12,
characterized,
that for quantization a spherical logarithmic quantization is used. Hearing aid (4), in particular a hearing aid, having a communication device (24) which is provided and arranged for transmitting and / or receiving an audio signal (16) according to a method (26) according to one of claims 1 to 13. Hearing aid system (2) with two hearing aids (4) according to claim 14, which is provided and set up, audio signals (16) between the two hearing aids (4) by means of their communication means (24) according to a method (26) according to one of claims 1 to 13 transferred to.

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