Method for directional signal processing for hearing devices

Abstract

The present invention relates to a method for directional signal processing of a hearing device, wherein a first input signal and a second input signal are generated respectively from environmental sound signals by first and second input converters of the hearing device, a first direction signal and a second direction signal are formed respectively according to the first input signal and the second input signal, the second direction signal has a relative attenuation along the direction of a first useful signal source, and the first direction signal has a relative attenuation along the direction of a second useful signal source, a first amplification parameter and a second amplification parameter are determined, a reference direction characteristic is defined, and a modified first amplification parameter and a modified second amplification parameter are determined according to the reference direction characteristic, so that when the first amplification parameter is equal to the second amplification parameter, the output direction signal is converted into a linearly scaled reference direction signal, and the output direction signal is formed as the sum of the first direction signal weighted by the modified first amplification parameter and the second direction signal weighted by the modified second amplification parameter.

Description

Technical Field

[0001] The invention relates to a method for directional signal processing for a hearing device, wherein a first input signal is generated from an ambient sound signal by a first input transducer of the hearing device, wherein a second input signal is generated from an ambient sound signal by a second input transducer of the hearing device, wherein a first directional signal and a second directional signal are respectively formed based on the first input signal and the second input signal, wherein the second directional signal has a relative attenuation in the direction of a first useful signal source (or in the direction of the first useful signal source), wherein the first directional signal has a relative attenuation in the direction of the second useful signal source, and wherein a first amplification parameter for amplifying a first useful signal of the first useful signal source and a second amplification parameter for amplifying a second useful signal of the second useful signal source are determined. Background Art

[0002] In a hearing device, the ambient sound is converted into an input signal by means of at least one input transducer, which is processed band-specifically and in particular individually in accordance with the hearing impairment of the wearer to be corrected, and is also amplified. The processed signal is converted into an output sound signal by an output transducer of the hearing device, which is conducted to the auditory system of the wearer. Within the scope of signal processing, automatic volume control (“automatic gain control”, AGC) and also dynamic compression are usually applied to the input signal or to an already preprocessed intermediate signal, wherein the input signal is usually linearly amplified only within certain limit values, and above the limit values, a smaller amplification is used in order to compensate for level peaks of the input signal. This is especially intended to prevent sudden, loud sound events from leading to output sound signals that are too loud for the wearer due to additional amplification in the hearing device.

[0003] However, such an AGC with integrated dynamic compression primarily reacts to sound events independently of their direction. If the wearer of the hearing device is in a complex listening situation, such as a conversation with multiple conversation partners, one conversation partner may trigger compression, for example by briefly screaming or laughing loudly, thereby significantly reducing the conversational contribution of the other conversation participants, which can affect the wearer's intelligibility. Summary of the invention

[0004] The object of the present invention is to provide a method for directional signal processing in a hearing instrument which is also suitable for complex hearing situations with more than one useful signal source, in particular in combination with AGC and / or dynamic compression.

[0005] According to the invention, the technical problem is solved by a method for directional signal processing for a hearing device, wherein a first input signal is generated by a first input transducer of the hearing device from an ambient sound signal, wherein a second input signal is generated by a second input transducer of the hearing device from an ambient sound signal, wherein a first directional signal and a second directional signal are formed from the first input signal and the second input signal, respectively, wherein the second directional signal has a relative attenuation in the direction of a first useful signal source, wherein the first directional signal has a relative attenuation in the direction of a second useful signal source, and wherein a first amplification parameter for amplifying a first useful signal of the first useful signal source and a second amplification parameter for amplifying a second useful signal of the second useful signal source are determined.

[0006] According to the invention, a reference direction characteristic is defined for a reference direction signal which can be represented (or presented) as a superposition of a first direction signal and a second direction signal, wherein a modified first amplification parameter and a modified second amplification parameter are determined as a function of the reference direction characteristic in such a way that, when the first amplification parameter is equal to the second amplification parameter, the output direction signal is converted or transformed into a linearly scaled reference direction signal, the output direction signal being formed as the sum of the first direction signal weighted with the modified first amplification parameter and the second direction signal weighted with the modified second amplification parameter, and wherein at least one of the two modified amplification parameters differs from the corresponding basic amplification parameter. Advantageous and partly inventive embodiments are the subject of the following description.

[0007] The output directional signal having the required properties can be formed as a correspondingly described superposition or as a function of at least one suitable intermediate signal, wherein the output directional signal is formed in such a way that the required properties are met when both amplification parameters are identical.

[0008] The first direction signal can be formed here for further signal processing, so that in particular signal components of the first direction signal are respectively included in the output direction signal. In the case where the output direction signal is formed from signal components of at least one suitable intermediate signal, i.e., for example, the first and second direction signals and the output direction signal are formed from forwardly and backwardly directed cardioid signals, respectively, the first direction signal is formed in particular for determining the modified first amplification parameter and / or the modified second amplification parameter, since the directional information that can be extracted from the first direction signal, in particular about the second useful signal source, is particularly advantageous for this purpose.

[0009] Preferably, an output signal is generated as a function of the output direction signal, which is converted into an output sound signal by an output converter of the hearing device. In this case, in particular frequency band-dependent suppression and / or feedback of interfering noise and / or further signal processing steps can also be performed when generating the output signal from the output direction signal. In particular, the method can be implemented band-wise, so that first and second amplification parameters, first and second direction signals as well as a reference direction signal and finally corrected first and second amplification parameters and output direction signals are determined or defined individually for each frequency band or for a group of individual frequency bands.

[0010] The input converter here comprises in particular an electroacoustic converter which is designed to generate a corresponding electrical signal from a sound signal. In particular, when generating the first or second input signal by the corresponding input converter, preprocessing, for example in the form of linear preamplification and / or A / D (analog / digital) conversion, can also take place. In this case, the correspondingly generated input signal is provided in particular by an electrical signal, the current and / or voltage fluctuations of which substantially represent the sound pressure fluctuations of the air.

[0011] Preferably, the direction of the first useful signal source points towards the front half-space relative to the front direction of the user of the hearing device defined by the intended use of the hearing device. Particularly preferably, the first useful signal source is at least approximately in the front direction, so that a corresponding approximation of the front source can be made for signal processing in particular. Preferably, the direction of the second useful signal source points outside the angular range of + / -45°, particularly preferably + / -60° around the front direction. In particular, the direction of the second useful signal source points towards the rear half-space.

[0012] The relative attenuation of the first directional signal is understood in particular to mean that the relevant directional characteristic has a sensitivity (or sensitivity) in the direction of the second useful signal, which sensitivity is reduced compared to the sensitivity averaged over all directions and has in particular a local, preferably global minimum. Preferably, the first and second directional signals have as complete an attenuation as possible in the direction of the second or first useful signal source.

[0013] The invention solves the following technical problem in particular: if the output directional signal is formed from two directional signals, each of which has a relative, preferably complete attenuation in the direction of a further useful signal source, then, for example, the amplification of the second useful signal by the output directional signal formed thereby depends not only on the corresponding amplification parameter, with which the second directional signal is weighted, but also on the direction of the second useful signal source, since the second directional signal thus has a non-trivial directional dependence. If the first directional signal has a complete or almost complete attenuation in the direction of the second useful signal source, then this directional dependence cannot be compensated by the correction term of the first directional signal. This can apply analogously to the amplification of the first useful signal by the first directional signal.

[0014] Therefore, a corresponding correction must be made by the contribution of the corresponding directional signal itself. Within the scope of the invention, this is solved by correcting the "scaling" of the corresponding directional signal, i.e. adjusting the corresponding amplification parameter, so that the corrected amplification parameter allows on the one hand to take into account this directional dependence of the corresponding directional signal.

[0015] On the other hand, the reference directional characteristic is predefined as a "normal state" which is to be achieved when two useful signals are to be amplified with the same amplification parameters (it is assumed here that this applies in particular to identical useful signals which arrive only from different directions). In this case, the amplification of the respective "equally loud" useful signals is to achieve a reference state, i.e., an omnidirectional directional characteristic or a directional characteristic which models the filtering achieved by the pinna, for example.

[0016] It is thus possible to amplify not only the useful signals from the front useful signal sources, but also useful signals from the rear half-space, for example, independently of their specific direction, by compensating for the influence of the directional effects of the directional signal including the relevant useful signal by correspondingly correcting the amplification. Equivalent formulas at the level of intermediate signals which can form the directional signal are also possible here.

[0017] For this purpose, the reference directional signal is preferably represented based on the two directional signals, so that the modified amplification parameter can be determined as a function of the corresponding coefficients in the expression. It is in particular possible here that, for example, only the modified second amplification parameter has a truly non-trivial modification relative to the second amplification parameter, while the modified first amplification parameter is identical to the first amplification parameter. However, the two modified amplification parameters, i.e. the first and second amplification parameters, can also differ from their respective first or second amplification parameters on which they are based. This can in particular be the case if neither of the two useful signal sources is occupied in a preferred direction relative to the hearing device, for example the frontal direction.

[0018] Advantageously, the modified second amplification parameter is determined such that the second useful signal is amplified by the second amplification parameter relative to the reference directional characteristic by the output directional signal (or the second useful signal is amplified by the second amplification parameter relative to the reference directional characteristic by the output directional signal), and / or wherein the modified first amplification parameter is determined such that the first useful signal is amplified by the first amplification parameter relative to the reference directional characteristic by the output directional signal. This achieves that, by means of the output directional signal, each of the two useful signals is amplified with the amplification parameter that is "correct" for the individual useful signals, respectively, regardless of the direction of the respective useful signal source.

[0019] Now, fundamentally this can only be achieved in the following way, that is, the signal contribution from the second useful signal, for example, in the output direction signal, i.e., the corresponding second direction signal, for example, can be weighted in accordance with the modified second amplification parameter in such a way that the directional dependence of the second direction signal (or a similar signal formed from at least one suitable intermediate signal and having a relative attenuation in the direction of the source of the first useful signal) can be compensated by the correction in the modified second amplification parameter. This applies analogously to the signal contribution of the first useful signal in the output direction signal. In particular, the modified first amplification parameter can be identical to the first amplification parameter.

[0020] The corrected second amplification parameter is expediently formed as a product of the second amplification parameter and a correction factor, wherein the correction factor corresponds to a linear coefficient of the second direction signal when the reference direction signal is represented as a linear combination of the first direction signal and the second direction signal.

[0021] The mathematical formula can be implemented as follows: If the input signals E1 and E2 are combined into a vector E = [E1, E2] T , then we can use the weights of the two input signals w = [w1, w2] T At least approximately represents the first direction signal Xr1 formed according to the two input signals, that is, Xr1 = E T w (as long as the acoustic propagation time between the two input transducers is smaller than the sample, which is usually the case). In a similar manner, the second direction signal Xr2 can be expressed as Xr2 = E T u, where weight u = [u1,u2] T .

[0022] The output direction signal Xout can then be expressed using the (scalar!) modified first and second amplification parameters G1', G2' as

[0023] (i) Xout = E T ·(G1'·w+G2'·u).

[0024] If the reference direction signal Xref is also represented based on E1 and E2, then the corresponding weighting vector wref=[wr1,wr2] is also obtained here. T :Xref=E T According to the first and second direction signals Xr1 and Xr2, the reference direction signal can be expressed as:

[0025] (ii) Xref = a·Xr1+b·Xr2, and therefore

[0026] (ii')wref=a·w+b·u (for two vector components)

[0027] Now implement equation (ii') and h T (α) is multiplied on the left, where h(α) = [h1(α), h2(α)] T represents a (measured, estimated or modeled) transfer function on the hearing device, which for example takes into account the propagation of sound from the sound source to the first input transducer or the second input transducer and for α=0° is converted into a relative transfer function from the first input transducer to the second input transducer with respect to a frontal sound source, and α is the angle for which preferably h T (α)·u=0 (ie the angle of the direction for which the second directional signal preferably has at least approximately complete attenuation, ie the direction of the source of the first useful signal). T (α)·wref and h T Knowledge of (α)·w determines the value of a (the two scalar products can be tabulated in particular for different values ​​of w1, w2 and α). From the value of a, the value of b can also be determined in one of the two components of (ii′).

[0028] It can be confirmed that the modified amplification parameter

[0029] (iii) G1' = a·G1,

[0030] G2'=b·G2

[0031] The desired characteristics are met for conversion, in the output direction signal Xout according to equation (i), to a reference direction signal Xref scaled with G1 for G1=G2.

[0032] It has proven to be advantageous to determine the modified first amplification parameter as the first amplification parameter if the second directional signal has its minimum sensitivity in the direction of the source of the first useful signal and preferably has the most complete attenuation possible in this direction and particularly preferably the first directional signal has its maximum sensitivity. If for the first directional signal Xr1 the direction of maximum sensitivity lies in the direction of the first useful signal in which the second directional signal has its minimum sensitivity, this can be used in particular for normalizing the first directional signal so that the sensitivity in this direction is set to 1 and thus h T (α)·w=1 is applicable. Additionally, if the attenuation of the second directional signal in this direction is at least approximately complete, ie h T (α)·u≈0, then a=1 can be set in equation (ii), thereby obtaining G1′=G1 in equation (iii), that is, the first amplification parameter and the modified first amplification parameter are the same.

[0033] Preferably, a first intermediate signal and a second intermediate signal are formed from the first input signal and the second input signal, wherein the first direction signal is formed as a superposition of the first intermediate signal and the second intermediate signal and the associated first superposition parameter is determined therein, and / or the second direction signal is formed as a superposition of the second intermediate signal and the first intermediate signal and the associated second superposition parameter is determined therein. Forward and backward directed cardioid signals Xc, Xa are used in particular as the first intermediate signal and the second intermediate signal. The first superposition parameter a1 or the second superposition parameter a2 is given by the expression

[0034] (iv) Xr1=Xc+a1·Xa,

[0035] Xr2=a2·Xc+Xa,

[0036] is obtained and can in particular be determined adaptively. In the important special case, a2=0, i.e. the second directional signal Xr2 is provided (or given) by the backward-pointing cardioid signal Xa and therefore by the second intermediate signal Z2. This is, for example, the case when a first useful signal source, for which the second directional signal has a relative, preferably maximum, and particularly preferably complete attenuation, is located in the region of the notch of the backward-pointing cardioid signal or is received there.

[0037] In an advantageous embodiment, the first corrected amplification parameter G1 ′ is formed as the product of the first amplification parameter G1 and the first correction factor a, and the second corrected amplification parameter G2 ′ is formed as the product of the second amplification parameter G2 and the second correction factor b.

[0038] Preferably, a first reference superposition parameter aref1 and a second reference superposition parameter aref2 are defined for superposition of the first intermediate signal Z1 and the second intermediate signal Z2, the superposition forming the reference direction signal Xref, wherein the first correction factor a is formed as a function of the product of the second superposition parameter a2 and the second reference superposition parameter aref2, and in particular as a function of the difference between the product and the first reference superposition parameter aref1, and / or wherein the second correction factor b is formed as a function of the difference between the product of the first superposition parameter a1 and the first reference superposition parameter aref1 and the second reference superposition parameter aref2. Preferably, the output direction signal Xout is formed as a function of the first direction signal Xr1 weighted with the modified first amplification parameter G1' and as a function of the second direction signal Xr2 weighted with the modified second amplification parameter G2' according to equation (iii)

[0039] (v)Xout=G1′·Xr1+G2′·Xr2

[0040] (v')=a·G1·Xr1+b·G2·Xr2.

[0041] From equations (iv) and (ii), Xref can be provided from the forward and backward pointing cardioid signal Xc or Xa (ie from the two intermediate signals Z1 and Z2 and currently with Z1=Xc and Z2=Xa) as:

[0042] Xref=(a+b·a2)·Xc+(a·a1+b)·Xa,

[0043] (ii”)Xref=aref1·Xc+aref2·Xa.

[0044] The linear factor assigned to the forward or backward directed cardioid signal Xc or Xa in equation (ii") can be interpreted as the first or second reference superposition parameter aref1 or aref2, ie

[0045] (vi)aref1=a+b·a2,

[0046] aref2=a·a1+b.

[0047] The correction factors a and b in equation (v') are generated based on the two reference superposition parameters aref1 and aref2:

[0048] (vii)a=(aref1–a2·aref2) / (1–a1·a2),

[0049] b=(aref2–a1·aref1) / (1–a1·a2).

[0050] For the special case aref1 = 1, equation (vii) is transformed into

[0051] (vii')a=(1–aref2·a2) / (1–a1·a2),

[0052] b=(aref2–a1) / (1–a1·a2).

[0053] In a further advantageous design scheme, the first effective superposition parameter aeff1 and the second effective superposition parameter aeff2 are determined based on the first and second superposition parameters a1, a2, based on the first and second reference superposition parameters aref1, aref2, based on the first amplification parameter G1 and based on the second amplification parameter G2, wherein the output direction signal Xout is formed based on the superposition of the first intermediate signal Z1 weighted by the first effective superposition parameter aeff1 and the second intermediate signal Z2 weighted by the second effective superposition parameter aeff2, that is, in particular, it is formed as Xout∝aeff1·Z1+aeff2·Z2.

[0054] Using the definitions of equations (iv) and (iii), the following expression can also be derived from equation (v):

[0055] (viii) Xout=G1·[(a+b·a2·G2 / G1)·Xc+(a·a1+b·G2 / G1)·Xa].

[0056] A similar expression can be obtained by introducing the second amplification parameter G2 in brackets, wherein the expression selected in equation (viii) (introducing G1 in brackets) is particularly advantageous for the case where G1 ≥ G2. The linear factor associated with the forward or backward pointing cardioid signal Xc or Xa in equation (viii) can be interpreted as the first or second effective superposition parameter aeff1 or aeff2, i.e.

[0057] (ix) aeff1=a+b·a2·G2 / G1,

[0058] aeff2=a·a1+b·G2 / G1,

[0059] where a and b are provided by expressions according to equation (vii) (or for the special case aref1=1, by equation vii'), so that equation (viii) is converted to:

[0060] (viii')Xout=G1·(aeff1·Xc+aeff2·Xa).

[0061] For G1=G2, the first and second effective superposition parameters aeff1, aeff2 are converted into first and second reference superposition parameters aref1, aref2 according to equation (vi). This can now be used to first represent two correction parameters a, b, which are assigned to the two amplification parameters G1, G2 according to equation (iii), and finally represent the two effective superposition parameters aeff1, aeff2 according to the reference superposition parameters aref1, aref2.

[0062] Preferably, the form of Xout to be specifically selected, ie according to equation (v) or equation (viii'), is implemented depending on which of the two expressions (ii), (ii") is actually used for Xref. In particular, the value aref1=1 can be predefined for equation (ii").

[0063] When the second direction signal Xr2 is provided by the second intermediate signal Z2 , ie in particular by the backward-pointing cardioid signal Xa (and therefore a2=0 applies in equation iii), the first effective superposition parameter aeff1 is formed from the first reference superposition parameter aref1 , ie aeff1=aref1.

[0064] In addition, from equation (v), the following expressions can be derived for Z1=Xc, Z2=Xa according to some variations:

[0065] (x)Xout=Geff·(Z1+(aeff2 / aeff1)·Z2)

[0066] Wherein the effective amplification parameter Geff=(G1'+G2'·a2), and the ratio of the effective superposition parameters aeff2 / aeff1=(G1'·a1+G2') / Geff. According to the requirement, that is, for G1=G2, the output signal Xout should be converted into the scaled reference signal Xref, and thus the effective superposition parameters aeff1, aeff2 are converted into the corresponding reference superposition parameters aref1, aref2, and by the additional requirement, that in this case the output signal Xout can be amplified by the first amplification parameter G1, that is, Geff=G1, the following equation is obtained:

[0067] (xi)G1=Geff=G1·a+G2·b·a2,

[0068] aref1=aeff1=a+b·a2,

[0069] aref2=aeff2=a·a1+b.

[0070] For the above-mentioned special case, i.e. the second direction signal Xr2 is provided by the second intermediate signal Z2 (in particular in the form of a backward-pointing cardioid signal Xa), and therefore a2=0 applies, and the first reference superposition parameter is set to aref1=1, the first correction factor is a=1 (see equation vii'). Therefore, the modified first amplification parameter G1' is identical to the first amplification parameter G1. For the second correction factor b, b=aref2-1 applies.

[0071] Thus, the output signal is obtained:

[0072] (xii)Xout=G1·(Z1+a1·Z2)+G2·(aref2–a1)·Z2.

[0073] It is obvious that for G1=G2, (xii) is converted into a reference direction signal Xref=Z1+aref2·Z2 scaled by G1 with a second reference superposition parameter aref2.

[0074] In the case where the second direction signal Xr2 is provided by the second intermediate signal Z2, it is advantageous if the second effective superposition parameter is formed by the first superposition parameter a1 and the ratio G2' / G1 of the modified second amplification parameter G2' to the first amplification parameter.

[0075] If the second useful signal is to be increased largely only by the second intermediate signal, then according to the first direction signal Xr1=Z1+a1·Z2, in the special case mentioned (in equation ix, aref1=1, a2=0, and therefore aeff1=1), according to equation (x) in particular a formula equivalent to equation (xii) can be obtained:

[0076] Xout=G1·(Z1+(aeff2 / aeff1)·Z2)

[0077] (xiii)=G1·{Z1+[a1+(aref2–a1)·G2 / G1]·Z2},

[0078] Therein, the term (aref2−a1)·G2 in aeff2 forms the modified second amplification parameter G2'. It should be noted that, for the case mentioned, the second direction signal Xr2 is provided by the second intermediate signal Z2, and therefore the second superposition parameter is set to a2=0. Thus, in equation (x), the effective amplification parameter Geff becomes G1 (a=1), which is taken into account in equation (xiii).

[0079] It has proven to be further advantageous if the reference directional characteristic of the reference directional signal is selected as an omnidirectional directional characteristic or in such a way that a masking effect of the human ear is simulated.

[0080] If the forward-pointing and backward-pointing cardioid signals Xc, Xa are used as intermediate signals for signal processing, for example to form at least a first directional signal, then in the case of an omnidirectional reference directional characteristic, the values ​​applicable for the two reference superposition parameters aref1, aref2 in the reference directional signal Xref=aref1·Xc+aref2·Xa are aref1=1, aref2=-1. In many cases, it is desirable to take as omnidirectional a hearing as possible as a starting point.

[0081] For the case where the masking effect of the human ear is to be simulated by the reference directional characteristic, the reference superposition parameters aref1, aref2 are preferably determined in advance so that the reference directional signal Xref=aref1·Xc+aref2·Xa simulates the desired spatial sensitivity as formed by the masking of the auricle on the human ear. In this case, aref1, aref2 can be determined on a universal ear model (e.g., of KEMAR) or can also be individually coordinated with the wearer of the hearing device by corresponding measurements.

[0082] Preferably, the first directional signal has a maximum attenuation in the direction of the first useful signal source and / or the second directional signal has a maximum, in particular complete, attenuation in the direction of the second useful signal source. This makes it possible to minimize the influence of the respective useful signal on the respective other directional signal and thus on the relative amplification parameter in a particularly effective manner.

[0083] Advantageously, the first directional signal is generated by means of an adaptive directional microphone, in particular as a function of the first intermediate signal and the second intermediate signal, and / or the second directional signal is generated by means of an adaptive directional microphone, in particular as a function of the first and second intermediate signals. It is thereby possible that the relevant directional signal has, on the one hand, the smallest possible, preferably the smallest, sensitivity in the direction of one of the two useful signal sources, thereby achieving a high, preferably the largest, attenuation in this direction, and has, on the other hand, the largest possible, preferably the largest, sensitivity in the direction of the respective other useful signal source.

[0084] It has been found to be further advantageous that the first intermediate signal is generated as a function of a superposition of the first input signal with a time delay of the second input signal achieved by means of a first delay parameter and / or that the second intermediate signal is generated as a function of a superposition of the second input signal with a time delay of the first input signal achieved by means of a second delay parameter. The first and second delay parameters can in particular be selected to be identical to one another and in particular the first intermediate signal can be generated symmetrically to the second intermediate signal with respect to a preferred plane of the hearing device, wherein the preferred plane preferably corresponds to a frontal plane assigned to the wearer when the hearing device is worn. The orientation of the directional signal in the frontal direction of the wearer facilitates signal processing, since the natural viewing direction of the wearer is thereby taken into account.

[0085] Preferably, the first intermediate signal is generated as a cardioid directional signal pointing forward, and / or the second intermediate signal is generated as a cardioid directional signal pointing backward. The cardioid directional signal can be formed in such a way that the two input signals are superimposed on each other with an acoustic propagation time delay corresponding to the distance of the input transducers. Thus, depending on the sign of this propagation time delay during superposition, the direction of maximum attenuation is in the front direction (cardioid directional signal pointing backward) or in the opposite direction thereto (cardioid directional signal pointing forward). The direction of maximum sensitivity is opposite to the direction of maximum attenuation. This makes further signal processing easier, since such an intermediate signal is particularly suitable for adaptive directional microphones.

[0086] The invention also relates to a hearing system having a hearing device having a first input converter for generating a first input signal from an ambient sound signal and a second input converter for generating a second input signal from an ambient sound signal, and having a control unit, which is designed to implement the aforementioned method. The control unit can be integrated in the hearing device in particular. In this case, the hearing system is provided directly via the hearing device. Essentially, the advantages mentioned for the method and its extended design can be transferred to the hearing system. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] The embodiments of the present invention are described in more detail below with reference to the accompanying drawings. Here, schematically:

[0088] Figure 1 shows a conversation situation of a wearer of a hearing device with two conversation partners; and

[0089] Figure 2 Shown in accordance with Figure 1 preferred directional signal processing for hearing devices in conversation situations;

[0090] Figure 3a Shown by Figure 2 directional characteristics of the output signal generated by the directional signal processing; and

[0091] Figure 3b shows an alternative by Figure 2 Directional signal processing produces a directional characteristic of the output signal.

[0092] Parts and variables that correspond to one another are provided with the same reference symbols in all the figures. DETAILED DESCRIPTION

[0093] Figure 1A wearer 1 of a hearing device 2 is schematically shown in a top view, the wearer being in a conversation situation with a first conversation partner 4 and a second conversation partner 8. The first conversation partner 4 is positioned in a first direction 6 relative to the wearer 1, and the second conversation partner 8 is positioned in a second direction 10 relative to the wearer 1. The first conversation partner 4 is the main conversation partner of the wearer 1, and the second conversation partner 8 participates in the conversation only through individual language contributions. The conversation situation described here is for Figure 1 The above and the following figures are the same. The language contribution of the first dialogue partner 4 In this case, a first useful signal S1 is formed, and the speech contribution of the second conversation partner 8 forms a second useful signal S2 .

[0094] In order to reduce the level peaks of the first useful signal S1 and the second useful signal S2 for the wearer 1 of the hearing device 2 in the output sound signal of the hearing device 2, as in Figure 1 As shown in the above figure, firstly, a first directional signal Xr1 is generated by means of an adaptive directional microphone, so that this first directional signal has a maximum and preferably complete attenuation in the second direction 10 (the second conversation partner 8 is positioned along the second direction). This means that the useful signal S2 is not included in the first directional signal Xr1. Therefore, the compression factor calculated based on the first directional signal Xr1 only responds to the first conversation partner with respect to the two useful signal sources 14, 18 provided by the first or second conversation partner 4 and 8. In this case, a first amplification parameter G1 is determined, which determines the optimal signal amplification for each moment with respect to the first useful signal S1 of the first useful signal source 14 (i.e., the first conversation partner 4), and therefore implicitly also determines the corresponding compression ratio.

[0095] exist Figure 1 In the lower figure of FIG. , similar to the upper figure, a second directional signal Xr2 is shown in the same hearing situation, which has a maximum, preferably complete attenuation in the first direction 6, that is, in the direction of the first conversation partner 4. Since the first direction 6 coincides with the front direction of the wearer 1, the second directional signal Xr2 is designed as a cardioid directional signal Xa pointing backwards. Therefore, the second amplification parameter G2 determined according to the second directional signal Xr2 and assigned thereto always represents the optimal amplification with respect to the second useful signal S2, and in particular the associated compression ratio.

[0096] In order to be able to reduce the level peaks caused by the conversational contributions of the first conversation partner 4 and the second conversation partner 8 in the output sound signal of the hearing device 2 for the wearer 1 of the hearing device by means of compression to a level that is comfortable for the wearer 1, this output sound signal can now be formed on the one hand from a linear combination of the first and second directional signals Xr1, Xr2, which are weighted with their respective amplification parameters G1, G2. Since the first directional signal Xr1 is also formed by means of an adaptive directional microphone from a forward-pointing cardioid directional signal and from a backward-pointing cardioid directional signal Xa, this linear combination results in an output sound signal whose directional characteristic is similar to the shape of the directional characteristic of the first directional signal Xr1, but wherein the notch 22 of the maximum attenuation is shifted away from the second direction 10. This leads on the one hand to a possibly undesirable, completely "deaf" region away from the second useful signal source 18, which on the other hand, due to the dependence of this linear combination on the speech contribution of the first conversation partner 4, can also fluctuate in its orientation.

[0097] Figure 2 The block diagram schematically shows a Figure 1 The situation described in Figure 1 A method for directional signal processing of a hearing device 2 is provided, which method is intended in particular to reduce the level peaks of the two useful signals S1, S2 of the useful signal sources 14, 18 provided by the respective conversation partners 4, 8. A first input converter 24 and a second input converter 26 are arranged in the hearing device 2, which generate the first input signal E1 and the second input signal E2 respectively from the sound signal 28. The sound signal 28 is the ambient sound here, which also contains the first and second useful signals S1, S2. Possible preprocessing, such as A / D conversion, etc., should already be included in the input converters 24, 26, which also each have a preferably omnidirectional microphone.

[0098] The first input signal E1 is now superimposed with the second input signal E2 delayed by the first delay parameter T1, and a first intermediate signal Z1 is formed thereby. Similarly, the second input signal E2 is superimposed with the first input signal E1 delayed by the second delay parameter T2, and a second intermediate signal Z2 is formed thereby. Presently and without limiting the generality, the first and second delay parameters T1, T2 are respectively selected to be identical (T1=T2) and are furthermore selected such that the first intermediate signal Z1 is provided by the forward-pointing cardioid directional signal Xc and the second intermediate signal Z2 is provided by the backward-pointing cardioid directional signal Xa. Now, based on the first intermediate signal Z1 and the second intermediate signal Z2, according to Figure 1By means of the adaptive directional microphone 40, a first direction signal Xr1=Z1+a1·Z2 is generated while determining the first superposition parameter a1, so that the contribution of the second conversation partner 8, that is, the second useful signal S2, is maximally suppressed in the first direction signal Xr1. Based on the first direction signal Xr1, a first amplification parameter G1 is determined for the first useful signal S1. Therefore, the determined first amplification parameter G1 represents the optimal amplification and compression of the signal contribution of the first conversation partner 4 by the first direction signal Xr1.

[0099] With the help of the adaptive directional microphone 42, a second direction signal Xr2 can be generated from the first intermediate signal Z1 and the second intermediate signal Z2, which second direction signal maximally suppresses the contribution of the first conversation partner 4, that is, the first useful signal S1. Since the first conversation partner is currently located in the front direction relative to the wearer 1, the second direction signal Xr2 is provided by the backward-pointing cardioid direction signal Xa, as already mentioned. The second direction signal Xr2 can be continuously assumed to be the backward-pointing cardioid direction signal Xa. On the other hand, with the help of the adaptive directional microphone 42, changes in the position of the first conversation partner 4 can also be taken into account for forming the second direction signal Xr2 from the first and second intermediate signals Z1, Z2.

[0100] Analogously to the first amplification parameter G1, the second amplification parameter G2 is also determined as a function of the second direction signal Xr2. The second amplification parameter represents the optimal amplification and compression of the second useful signal S2 by the second direction signal Xr2.

[0101] Furthermore, a reference direction characteristic 63 is defined for the reference direction signal Xref. The reference direction signal Xref is generated here as a superposition of two intermediate signals Z1, Z2:

[0102] Xref=aref1·Z1+aref2·Z2

[0103] That is, it has a corresponding first reference superposition parameter aref1 and a second reference superposition parameter aref2, which are selected so that the reference direction signal Xref has a desired reference direction characteristic 63, that is, for example, in particular, a spatial filtering effect of the auricle on the human ear is simulated in a band-like manner. For some or all frequency bands, an omnidirectional direction characteristic can also be selected for the reference direction signal Xref (the reference direction signal thereby loses its directionality). Here, the reference direction signal Xref is used to define the reference direction characteristic 63 and the reference superposition parameters aref1, aref2, and does not have to be generated as an independent signal from the two intermediate signals Z1 and Z2 (respectively shown by dotted lines); on the contrary, the reference superposition parameters aref1, aref2 can be determined in advance. In particular, it can be determined that aref1=1, so that the reference direction characteristic 63 of the reference direction signal Xref is not attenuated in the front direction.

[0104] Now, for the following calculations it is taken into account that Xr2=Z2=Xa and therefore a2=0 applies, wherein aref1=1 is also set.

[0105] Based on the second magnification parameter G2, the first superposition parameter a1 and the reference superposition parameter aref2, the modified second magnification parameter G2' is now determined as:

[0106] G2'=G2·(aref2–a1).

[0107] Now, the output direction signal Xout is formed as follows based on the first direction signal Xr1=Z1+a1·Z2, weighted by the first amplification parameter G1, and based on the second direction signal Xr2, which currently corresponds to the second intermediate signal Z2, weighted by the modified second amplification parameter G2':

[0108] Xout=G1·Xr1+G2'·Z2

[0109] (xii')=G1·(Z1+a1·Z2)+G2·(aref2–a1)·Z2.

[0110] Now, if, for example, the first useful signal S1 and the second useful signal S2 are equally loud in a frequency range, they are each assigned the same amplification parameter G1=G2 for this frequency range. In this case, in the output direction signal Xout, the contributions cancel each other out proportionally to the first superposition parameter a1, and the output direction signal Xout is converted to Xout=G1·(Z1+aref2·Z2), i.e., to the reference direction signal Xref amplified ("scaled") by G1.

[0111] Instead of the illustrated generation of the output direction signal Xout from the first direction signal Xr1 and the backwards directed cardioid signal Xa as the second intermediate signal Z2, the output direction signal Xout can also be generated in such a way that the first effective superimposition parameter aeff1 and the second effective superimposition parameter aeff2 are formed as a function of the first superimposition parameter a1, as a function of the modified second amplification parameter G2' and as a function of the first amplification parameter G1:

[0112] aeff2=a1+G2' / G1

[0113] (xiv)=a1+(aref2–a1)·G2 / G1.

[0114] In the present special case, the first effective superposition parameter aeff1 has the value aeff1=1, but can also have non-trivial values, in particular for a2≠0. The correspondingly formed output direction signal

[0115] Xout=G1·(aeff1·Z1+aeff2·Z2)

[0116] Wherein, by aeff2 according to equation (xiv) and aeff1=1, it is presented in the form described in equation (xii'). Due to the current generation, the output direction signal Xout has a directional characteristic, which has an amplification or attenuation of a factor G1 relative to the reference direction signal Xref in the direction of the first useful signal source 14 (i.e., the direction of the first useful signal S1), and has an amplification or attenuation of a factor G2 relative to the reference direction signal Xref in the direction of the second useful signal source 18 (i.e., the direction of the second useful signal S2) (see also Figure 3a and Figure 3b ).

[0117] As a function of the output direction signal Xout, an output signal Yout is finally generated by a signal processing step 50 , which may in particular include an additional frequency band-dependent noise suppression, and is converted by an output converter 52 of the hearing instrument 2 into an output sound signal 54 .

[0118] exist Figure 3a For wearer 1 Figure 1 The listening situation shown shows that Figure 2 The directional characteristic 60 of the output directional signal Xout generated as described in FIG. The reference directional characteristic 62 (dashed line) is provided here as an omnidirectional directional characteristic. For better intuitiveness, the first amplification parameter G1 is selected as 0 dB, and the second amplification parameter G2 is selected as -6 dB. The formed directional characteristic 60 of the output directional signal Xout has a significant deviation from the omnidirectional reference directional characteristic 62 along the second direction 10 (i.e., the direction of the second useful signal source 18).

[0119] exist Figure 3b , instead of the omnidirectional reference directional characteristic 62, a reference directional signal Xref (dashed line) with a reference directional characteristic 64 is selected, which models the filtering of the ambient sound by the auricle and the corresponding masking effect. The first amplification parameter G1 is again selected as 0 dB here, and the second amplification parameter G2 is selected as -6 dB. The resulting directional characteristic 66 of the output directional signal Xout again has a significant deviation from the omnidirectional reference directional characteristic 64 in the direction of the second useful signal source 18, wherein now an additional attenuation is achieved in this direction by the definition of the reference directional signal Xref, which is included in the reference directional characteristic 64 due to the masking effect of the auricle.

[0120] Although the present invention has been described in detail by means of preferred embodiments, the present invention is not limited to the disclosed examples and other variations may be derived therefrom by those skilled in the art without departing from the scope of protection of the present invention.

[0121] Reference numerals list

[0122] 1 Wearer

[0123] 2 Hearing devices

[0124] 4 First dialogue partner

[0125] 6 First Direction

[0126] 8 Second dialogue partner

[0127] 10 Second Direction

[0128] 14 First useful signal source

[0129] 18 Second useful signal source

[0130] 22 Notch

[0131] 24 First input converter

[0132] 26 Second input converter

[0133] 28 Sound signal

[0134] 40 Adaptive directional microphone

[0135] 42 Adaptive directional microphones

[0136] 50 Signal Processing Steps

[0137] 52 Output Converter

[0138] 54 Output sound signal

[0139] 60 Directional characteristics

[0140] 62 (omnidirectional) reference directional characteristics

[0141] 63 Reference direction characteristics

[0142] 64 Reference direction characteristics

[0143] 66 Directional characteristics

[0144] a1 first superposition parameter

[0145] aeff1 The first effective superposition parameter

[0146] aeff2 Second effective superposition parameter

[0147] aref1 First reference superposition parameter

[0148] aref2 Second reference superposition parameter

[0149] E1 First input signal

[0150] E2 Second input signal

[0151] G1 first amplification parameter

[0152] G2 Second magnification parameter

[0153] G2' Corrected second magnification parameter

[0154] S1 First useful signal

[0155] S2 Second useful signal

[0156] T1 First Delay Parameter

[0157] T2 Second delay parameter

[0158] Xa Backward-pointing cardioid signal

[0159] Xc forward pointing cardioid signal

[0160] Xout output direction signal

[0161] Xr1 First direction signal

[0162] Xr2 Second direction signal

[0163] Yout Output Signal

[0164] Z1 First intermediate signal

[0165] Z2 Second intermediate signal

Claims

1. A method for directional signal processing for a hearing device (2), -in, A first input signal (E1) is generated from an ambient sound signal (28) by a first input converter (24) of the hearing device (2), wherein a second input signal (E2) is generated by a second input transducer (26) of the hearing device (2) from an ambient sound signal (28), - wherein a first direction signal (Xr1) and a second direction signal (Xr2) are respectively formed according to the first input signal (E1) and the second input signal (E2), - wherein the second directional signal (Xr2) has a relative attenuation in the direction of the first useful signal source (14), - wherein the first directional signal (Xr1) has a relative attenuation in the direction of the second useful signal source (18), wherein a first amplification parameter (G1) for amplifying a first useful signal (S1) of a first useful signal source (14) and a second amplification parameter (G2) for amplifying a second useful signal (S2) of a second useful signal source (18) are determined, - wherein a reference direction characteristic (62, 63, 64) for a reference direction signal (Xref) is defined, - wherein, according to the first amplification parameter (G1) and / or the second amplification parameter (G2), a modified first amplification parameter and a modified second amplification parameter (G2') are determined in accordance with the reference directional characteristic (62, 63, 64) such that when the first amplification parameter (G1) is equal to the second amplification parameter (G2), the output directional signal (Xout) is converted into a linearly scaled reference directional signal (Xref), the output directional signal being formed as the sum of a first directional signal (Xr1) weighted by the modified first amplification parameter and a second directional signal (Xr2) weighted by the modified second amplification parameter (G2'), and - wherein at least one of the two mentioned corrected amplification parameters differs from the corresponding basic amplification parameter (G2).

2. The method according to claim 1, in, The modified second amplification parameter (G2') is determined such that the second useful signal (S2) is amplified by the output direction signal (Xout) with the second amplification parameter (G2) relative to the reference directional characteristic (62, 63, 64), and / or The modified first amplification parameter is determined so that the first useful signal (S1) is amplified by the first amplification parameter (G1) via the output direction signal (Xout) relative to the reference directional characteristic (62, 63, 64).

3. The method according to claim 1 or 2, in, The corrected second amplification parameter (G2′) is formed as the product of the second amplification parameter (G2) and a correction factor, Wherein, when the reference direction signal (Xref) is represented as a linear combination of the first direction signal (Xr1) and the second direction signal (Xr2), the correction factor corresponds to a linear coefficient of the second direction signal (Xr2).

4. The method according to claim 1 or 2, in, If the first directional signal (Xr1) has its minimum sensitivity in the direction of the second useful signal source (18), the modified first amplification parameter is determined as the first amplification parameter (G1).

5. The method according to claim 1 or 2, in, forming a first intermediate signal (Z1) and a second intermediate signal (Z2) according to the first input signal (E1) and the second input signal (E2), wherein the first direction signal (Xr1) is formed as a superposition of a first intermediate signal (Z1) and a second intermediate signal (Z2), and a first superposition parameter (a1) associated therewith is determined, and / or The second direction signal (Xr2) is formed as a superposition of the second intermediate signal (Z2) and the first intermediate signal (Z1), and an associated second superposition parameter (a2) is determined in the process.

6. The method according to claim 1 or 2, in, The corrected first amplification parameter (G1') is formed as the product of the first amplification parameter (G1) and a first correction factor, Therein, the corrected second amplification parameter (G2') is formed as a product of the second amplification parameter (G2) and a second correction factor.

7. The method according to claim 5, in, The corrected first amplification parameter (G1') is formed as the product of the first amplification parameter (G1) and a first correction factor, Therein, the corrected second amplification parameter (G2') is formed as a product of the second amplification parameter (G2) and a second correction factor.

8. The method according to claim 7, in, A first reference superposition parameter (aref1) and a second reference superposition parameter (aref2) are defined for superposition of the first intermediate signal (Z1) and the second intermediate signal (Z2), said superposition forming a reference direction signal (Xref), wherein the first correction factor is formed according to the product of the second superposition parameter (a2) and the second reference superposition parameter (aref2), and / or The second correction factor is formed according to the difference between the product of the first superposition parameter (a1) and the first reference superposition parameter (aref1) and the second reference superposition parameter (aref2).

9. The method according to claim 6, in, The output directional signal (Xout) is formed from a first directional signal (Xr1) weighted with a modified first amplification parameter (G1') and from a second directional signal (Xr2) weighted with a modified second amplification parameter (G2').

10. The method according to claim 8, in, determining a first effective overlay parameter (aeff1) and a second effective overlay parameter (aeff2) according to the first overlay parameter (a1) and the second overlay parameter (a2), the first reference overlay parameter (aref1) and the second reference overlay parameter (aref2), and according to the first magnification parameter (G1) and the second magnification parameter (G2), and The output direction signal (Xout) is formed by superimposing a first intermediate signal (Z1) weighted by a first effective superposition parameter (aeff1) and a second intermediate signal (Z2) weighted by a second effective superposition parameter (aeff2).

11. The method according to claim 10, in, For the case where the second direction signal (Xr2) is provided by means of a second intermediate signal (Z2), the first effective superposition parameter (aeff1) is formed by a first reference superposition parameter (aref1).

12. The method according to claim 5, in, determining a second effective superposition parameter (aeff2) according to the first superposition parameter (a1), according to the modified first magnification parameter (G1') and according to the modified second magnification parameter (G2'), and The output direction signal (Xout) is formed by superimposing the first intermediate signal (Z1) and a second intermediate signal (Z2) weighted by a second effective superposition parameter (aeff2).

13. The method according to claim 12, in, For the case where the second direction signal (Xr2) is provided by the second intermediate signal (Z2), the second effective superposition parameter (aeff2) is formed by the first superposition parameter (a1) and the ratio of the modified second amplification parameter (G2') to the first amplification parameter (G1).

14. The method according to claim 1 or 2, in, The reference directional characteristic (63) of the reference directional signal (Xref) is selected to be the omnidirectional directional characteristic (62), or is selected to simulate the masking effect of the human ear.

15. A hearing system comprising: - a hearing device (2) having a first input transducer (24) for generating a first input signal (E1) from an ambient sound signal (28) and a second input transducer (26) for generating a second input signal (E2) from an ambient sound signal (28); and - A control unit designed to carry out the method according to any of the preceding claims.

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