EP3490270B1 - Method for operating a hearing aid - Google Patents

Method for operating a hearing aid Download PDF

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Publication number
EP3490270B1
EP3490270B1 EP18200729.4A EP18200729A EP3490270B1 EP 3490270 B1 EP3490270 B1 EP 3490270B1 EP 18200729 A EP18200729 A EP 18200729A EP 3490270 B1 EP3490270 B1 EP 3490270B1
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Prior art keywords
signal
dependent
noise
microphone
parameter
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German (de)
French (fr)
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EP3490270A1 (en
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Sebastian BEST
Cecil Wilson
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Sivantos Pte Ltd
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Sivantos Pte Ltd
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
    • H04R25/45—Prevention of acoustic reaction, i.e. acoustic oscillatory feedback
    • H04R25/453—Prevention of acoustic reaction, i.e. acoustic oscillatory feedback electronically
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R3/00—Circuits for transducers, loudspeakers or microphones
    • H04R3/005—Circuits for transducers, loudspeakers or microphones for combining the signals of two or more microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
    • H04R25/40—Arrangements for obtaining a desired directivity characteristic
    • H04R25/405—Arrangements for obtaining a desired directivity characteristic by combining a plurality of transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
    • H04R25/40—Arrangements for obtaining a desired directivity characteristic
    • H04R25/407—Circuits for combining signals of a plurality of transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
    • H04R25/50—Customised settings for obtaining desired overall acoustical characteristics
    • H04R25/505—Customised settings for obtaining desired overall acoustical characteristics using digital signal processing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2225/00—Details of deaf aids covered by H04R25/00, not provided for in any of its subgroups
    • H04R2225/41—Detection or adaptation of hearing aid parameters or programs to listening situation, e.g. pub, forest
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2225/00—Details of deaf aids covered by H04R25/00, not provided for in any of its subgroups
    • H04R2225/43—Signal processing in hearing aids to enhance the speech intelligibility

Definitions

  • the invention relates to a method for operating a hearing aid, a first direction-dependent signal and a second direction-dependent signal being generated in the hearing aid from a sound signal from the environment, and a noise-optimized signal being generated from the first direction-dependent signal and the second direction-dependent signal.
  • SNR signal-to-noise ratio
  • This is often achieved by means of direction-dependent signal processing algorithms. It is often assumed here that a strongly localized useful signal component is present in the sound signal from the surroundings which is received by the hearing aid, for example in the form of contributions from a conversation partner. This useful signal component is now delimited by means of direction-dependent signals in the hearing aid from a background assumed to be a noise signal, although the noise signal can also have a considerable directional dependency.
  • the algorithms mentioned often use self-optimization, the directional characteristic of a direction-dependent signal being adapted in such a way that the influence of interference signals from the direction in which their contribution is greatest is minimized. This is usually done by minimizing the signal power of a corresponding directional signal.
  • a direction-dependent output signal is often produced by a linear combination of a forward-facing cardioid with a backward-facing one Cardioid reached.
  • a change in the directional characteristic can be achieved via the adaptation coefficient, which determines the contribution of the backward-facing cardioid. In this way, the contributions of interference noise sources, which can lie in a wide solid angle range with respect to the forward direction of the hearing aid, can be reduced.
  • Impinging signals should be background noises that are suppressed by the corresponding portion of the backward cardioid.
  • the EP 2 658 2 89 A1 calls a method for controlling a directional characteristic of a microphone device in a hearing system, in which a first feature value for speech in a first signal of a microphone device assigned to a first direction and a second feature value for speech in a second signal of the microphone device assigned to a second direction is determined. A control value is obtained from the difference between the two feature values. The directional characteristic of the microphone device is controlled with this control value.
  • the DE 101 14 101 A1 calls a hearing aid with two microphones, in which setting parameters of a signal processing unit, which affect the directional characteristic, the frequency response, the signal increase, the choice of the hearing program or the noise reduction, are set depending on the result of a signal analysis of the two microphone signals.
  • the signal analysis includes at least one modulation analysis of the incoming signals.
  • the invention is therefore based on the object of specifying a method for operating a hearing aid, by means of which an interfering noise can be suppressed with the least possible influence by a useful signal, regardless of its direction.
  • the object is achieved according to the invention by a method for operating a hearing aid, with a first direction-dependent signal and a second direction-dependent signal being generated in the hearing aid from a sound signal from the environment, a parameter being determined based on the first direction-dependent signal and the second direction-dependent signal represents a quantitative measure of the stationarity of the sound signal, wherein a noise-optimized signal is generated from the first direction-dependent signal and the second direction-dependent signal based on the parameter, and the parameter is determined in a signal feedback loop from the noise-optimized signal.
  • the first direction-dependent signal and the second direction-dependent signal are each generated on the basis of corresponding signals from at least two input sound converters, which can each be given, for example, by microphones.
  • a direction-dependent signal is to be understood as a signal that has a non-trivial directional characteristic, that is, for a test sound with constant sound pressure and the corresponding test sound source at a constant distance from the hearing aid, the sensitivity to the test sound in the respective direction-dependent signal has a measurable, preferably considerable directional and, in particular, angular dependence in the transverse plane of the carrier.
  • a quantitative measure of stationarity is to be understood here in particular as a measure that assigns a numerical value to a signal in such a way that the extreme value of the measure is assumed for a pure sine tone of constant frequency, and a correspondingly monotonous change in the case of an increasing variation in frequencies of signal components recorded in the numerical value.
  • the parameter can represent an absolute quantitative measure, which measures the stationarity of the signals to be checked using a standardized scale, and in particular have a fixed maximum and a fixed minimum value, or a relative measure, which in particular does not have a fixed extreme value for non-stationary ones Having signals.
  • a noise-optimized signal includes, in particular, a signal which, with respect to the useful signal components contained in the sound signal, has an SNR that is optimized relative to the first direction-dependent signal and relative to the second direction-dependent signal, if the useful signal components in the sound signal are superimposed by interfering noise components.
  • the first direction-dependent signal and the second direction-dependent signal can enter the noise-optimized signal linearly, i.e. the noise-optimized signal has a linear response to a change in the time-frequency domain that occurs at a specific point in time in one of the two direction-dependent signals .
  • a common procedure for noise suppression in hearing aids is first of all to interpret the first direction-dependent signal in such a way that its direction of maximum sensitivity coincides with the frontal direction of the wearer.
  • the second direction-dependent signal is now designed so that, on the one hand, its direction of maximum sensitivity points in a direction other than the frontal direction of the wearer, and instead the direction of minimum sensitivity coincides with the frontal direction of the wearer.
  • the directional characteristic of the first direction-dependent signal is preferably mirrored with respect to the frontal plane of the wearer when it is worn properly during operation.
  • the first direction-dependent signal which primarily picks up the voice signal components of a conversation partner in the frontal direction, is now dependent on the total energy of a resultant Signal with the second direction-dependent signal superimposed.
  • the second direction-dependent signal can suppress signal components which do not impinge on the wearer from the frontal direction and are thus assumed to be interfering noises. Because of the constant contribution by the first direction-dependent signal in the frontal direction, only the mentioned condition of the minimum total energy of the signal resulting from the superposition is required for effective suppression of interfering noises.
  • the approach proposed in the invention is based on the consideration that strongly directed interference, such as can be given for example by the hum of a motor or a household appliance, can be satisfactorily suppressed by the previous approach when hitting the carrier from the side, however in the event that the signal impinging from the side is a useful signal, that is to say, for example, a speech signal from another speaker who joins the group, a suppression also takes place, which in this case would now be undesirable.
  • the parameter is determined in a signal feedback loop from the noise-optimized signal. While the parameter could also be determined from the first direction-dependent signal and the second direction-dependent signal - i.e. without further processing to form the noise-optimized signal itself - from a purely technical point of view, determining the parameter from the noise-optimized signal has the advantage that this signal is what is required for further processing in the hearing aid intended signal can be used as a target variable. Complex conversions can therefore be omitted.
  • an autocorrelation function is determined as the parameter.
  • the autocorrelation function is preferably to be determined via a time window which is to be suitably determined with regard to the expected useful signals and the expected interfering noises.
  • the advantage of using the autocorrelation function as a parameter is that it often offers additional valuable information which can be of importance in the subsequent signal processing.
  • the noise-optimized signal is generated by superimposing the first direction-dependent signal and the second direction-dependent signal, a weighting factor for the superimposition being determined on the basis of the parameter.
  • the noise-optimized signal is of the form F + ⁇ ⁇ B, where F denotes the first direction-dependent signal and B the second direction-dependent signal, and ⁇ is the weighting factor determined on the basis of the parameter.
  • this superimposition is particularly easy to implement technically; on the other hand, the first direction-dependent signal can be aligned in such a way that the direction of maximum sensitivity to a conversation partner of the carrier, in particular is aligned in the frontal direction, which further facilitates the determination of the weighting factor ⁇ .
  • the noise-optimized signal preferably has an essentially omnidirectional directional characteristic for a non-stationary sound signal due to the weighting factor, and a maximum directional characteristic for a maximum stationary sound signal due to the weighting factor.
  • a maximum directional directional characteristic is to be understood here in particular as a global maximum of the directional effect within the framework of the directional signals available. This takes into account the fact that, for non-stationary sound signals, it is assumed that there are no interfering noises to be suppressed, but that speech signals hitting the side of the carrier may be present. In this case, an essentially omnidirectional directional characteristic of the noise-optimized signal is advantageous, since this allows speech signals from all spatial directions to be taken into account.
  • a directional characteristic of the noise-optimized signal in such a way that only the spatial direction in which a conversation partner is assumed, i.e. usually the frontal direction, makes significant signal contributions to the delivers a noise-optimized signal.
  • An essentially omnidirectional directional characteristic is to be understood here in particular as such a directional characteristic in which a deviation from perfect omnidirectionality compared to the directional effects occurring can be neglected, in particular in the case of the directional directional characteristics.
  • the parameter is determined in such a way that the noise-optimized signal is minimal with regard to the parameter. This can be done in particular by minimizing the noise-optimized signal with regard to the parameter. This procedure has the advantage that the noise-optimized signal always has the lowest possible stationarity and thus always the lowest possible noise component.
  • the noise-optimized signal is expediently minimized with regard to its signal energy and with regard to the parameter.
  • the noise-optimized signal which is formed from the first direction-dependent signal and the second direction-dependent signal, has a local minimum as a function of the variable signal energy and the parameter.
  • interference noises can be suppressed in particular that impinge on the wearer from different directions in a complex hearing situation, with a diffuse noise background also being present, while the interfering noises themselves may only be partially assumed to be stationary.
  • the first direction-dependent signal and / or the second direction-dependent signal are generated on the basis of a time-delayed superposition of the first microphone signal with the second microphone signal.
  • the acoustic transit time difference between the first microphone and the second microphone is preferably used for the time delay in the superimposition.
  • the first direction-dependent signal has a directional dependency in the form of a first cardioid, which is oriented in a first direction
  • the second direction-dependent signal has a directional dependency in the form of a second cardioid, which is oriented in a second direction.
  • a cardioid-shaped signal is characterized in that the direction of minimum sensitivity is opposite to the direction of maximum sensitivity. This is not the case, for example, for signals whose directional characteristic forms a supercardioid or a hypercardioid.
  • a sound signal from the direction of minimum sensitivity is, ideally, completely suppressed with a cardioid-shaped directional characteristic.
  • the symmetry between the direction of the maximum and the minimum sensitivity thus allows calculations for the first and the second superimposition for noise suppression particularly easy to keep, since there is also a strictly monotonous increase in sensitivity from the direction of minimum sensitivity to the direction of maximum sensitivity.
  • the first direction is particularly preferably opposite to the second direction.
  • the superimposition is preferably first formed using the minimum signal power, then the quantitative parameter for the stationarity is determined for the resulting signal, and the weighting in the superimposition is now adjusted, in particular iteratively, using the parameter until the parameter is minimal, see above that the resulting signal has a minimum stationarity in relation to the parameter.
  • the invention also mentions a hearing aid with a first microphone and a second microphone for generating a first direction-dependent signal and a second direction-dependent signal, which is set up to carry out the method described above.
  • the first direction-dependent signal and the second direction-dependent signal are each generated by means of both the first microphone and the second microphone.
  • Prefers the method is carried out during operation of the hearing aid by means of a control unit which is particularly preferably designed as part of the signal processing unit in which all further functions of the signal processing are implemented.
  • a wearer 1 of a hearing aid 2 is shown schematically in a plan view.
  • the carrier 1 is in a conversation situation with a conversation partner 4 who is positioned in the frontal direction 6 of the carrier 1.
  • a first direction-dependent signal 8f dashed line
  • a second direction-dependent signal 8r dotted line
  • the cardioid-shaped directional characteristic of the first direction-dependent signal 8f has the consequence that there is a maximum sensitivity for sound signals from the frontal direction 6 and thus sound signals from this direction enter the first direction-dependent signal 8f at a maximum, while sound signals from the reverse direction 10 opposite to the frontal direction 6 ideally be completely suppressed in the first direction-dependent signal 8f.
  • the second direction-dependent signal 8r has one to the first direction-dependent signal 8f on opposite directional dependence, so that in the second direction-dependent signal 8r sound signals from the rearward direction 10 enter maximally, while sound signals from the frontal direction 6 are ideally completely suppressed.
  • the contribution of the second direction-dependent signal 8r is thus to be adjusted in the resulting signal using the weighting factor ⁇ so that the resulting signal has a minimum signal level, not least because of the unchangeable contribution of the useful signal from the frontal direction 6 (see above) due to the unchangeable contribution of the useful signal from the frontal direction 6 (see above) it is set that the attenuation of the signal components, which do not come from the frontal direction 6, is maximal.
  • a further speaker 14 comes in, whose speech signal 16 does not come from the frontal direction 6, but from a lateral direction at the wearer 1, the procedure just described would initially ensure that the speech signal 16 is treated like the background noises 12a, 12b and accordingly is suppressed. To avoid this, a detection is made as to whether the laterally incident noises 12a, 12b, 16 are interference noises or potential useful signals, and only the interference noises 12a, 12b are suppressed. This is based on Fig. 2 described.
  • a method 20 for directional noise suppression in hearing aid 2 is shown by means of a block diagram.
  • a first microphone signal 26a is generated from the sound signal 22 of the surroundings by means of a first microphone 24a
  • a second microphone signal 26b is generated by means of a second microphone 24b.
  • the second microphone signal 26b is delayed by the time interval T, so that a time-delayed second microphone signal 28b is formed, which is subtracted from the first microphone signal 26a, so that the first direction-dependent signal 8f is formed.
  • the first microphone signal 26a is additionally delayed by the time interval T, thereby forming the first time-delayed microphone signal 28a, which is subtracted from the second microphone signal 26b and thereby forming the second direction-dependent signal 8r.
  • the first direction-dependent signal 8f and the second direction-dependent signal 8r each have the cardioid-shaped directional characteristics according to FIG Fig. 1 on.
  • a weighting factor ⁇ is now determined in such a way that the signal 32 resulting from the superposition 30 has a minimum stationarity.
  • the resulting signal 32 is fed to a signal feedback loop 34, where a parameter 36 for the stationarity of the signal components is determined.
  • the parameter 36 can be given, for example, by an autocorrelation function which is to be calculated over a suitable time window to be selected.
  • the superposition 30 becomes in the signal feedback loop 34 not changed any further. If, however, it is determined in the signal feedback loop 34 that the resulting signal 32 has a stationarity parameter 36 which is not minimal, for example on the basis of a consideration of the monotony of the parameter 36 with small variations of ⁇ around the present value, the weighting factor ⁇ in the overlay 30 is adapted to the effect that the parameter 36 is minimized. In particular, this can be done interactively.
  • a parameter 36 is also conceivable, which provides an absolute measure of stationarity and is in particular suitably normalized so that based on the value of parameter 36 for an overlay with a weighting factor ⁇ and based on the corresponding distance between the value of parameter 36 and the minimum value a quantitative statement about the necessary adjustment of the weighting factor ⁇ becomes possible.
  • the weighting factor ⁇ is to be determined in such a way that the signal components of the interference noises 12a, 12b via the second direction-dependent signal B are eliminated as far as possible in F + ⁇ ⁇ B. This is done using a negative weighting factor ⁇ with an amount ⁇ 1.
  • the resulting signal 32 essentially corresponds to the signal that would also be achieved by minimizing the signal energy, since the speech signal 13, which enters the resulting signal 32 through F, is non-stationary, and its signal components are due to the corrections of the stationary signal components are not impaired by means of the signal B.
  • the weighting factor ⁇ is now positive and is designed in such a way that it compensates as far as possible for the attenuation of the speech signal 16 due to the lateral weakening of the directional characteristic of the first direction-dependent signal 8f.

Description

Die Erfindung betrifft ein Verfahren zum Betrieb eines Hörgerätes, wobei im Hörgerät aus einem Schallsignal der Umgebung ein erstes richtungsabhängiges Signal und ein zweites richtungsabhängiges Signal erzeugt werden, und wobei aus dem ersten richtungsabhängigen Signal und dem zweiten richtungsabhängigen Signal ein rauschoptimiert es Signal erzeugt wird.The invention relates to a method for operating a hearing aid, a first direction-dependent signal and a second direction-dependent signal being generated in the hearing aid from a sound signal from the environment, and a noise-optimized signal being generated from the first direction-dependent signal and the second direction-dependent signal.

In Hörgeräten ist eines der am häufigsten auftretenden Probleme, für bestimmte Hörsituationen das Signal-zu-Rausch-Verhältnis (SNR) zu verbessern. Dies wird oftmals mittels richtungsabhängiger Signalverarbeitungs-Algorithmen erreicht. Hierbei wird häufig davon ausgegangen, dass im Schallsignal der Umgebung, welches in das Hörgerät eingeht, eine stark lokalisierte Nutzsignalkomponente präsent ist, beispielsweise in Form von Gesprächsbeiträgen eines Gesprächspartners. Diese Nutzsignalkomponente wird nun mittels richtungsabhängiger Signale im Hörgerät gegenüber einem als Rauschsignal angenommen Hintergrund abgegrenzt, wobei jedoch auch das Rauschsignal eine erhebliche Richtungsabhängigkeit aufweisen kann. Generell verwenden die genannten Algorithmen dabei oftmals eine Selbstoptimierung, wobei die Richtcharakteristik eines richtungsabhängigen Signals so adaptiert wird, dass der Einfluss von Störsignalen aus derjenigen Richtung minimiert wird, in welcher ihr Beitrag am größten ist. Üblicherweise geschieht dies durch eine Minimierung der Signalleistung eines entsprechenden Richtsignals.One of the most common problems in hearing aids is improving the signal-to-noise ratio (SNR) for certain listening situations. This is often achieved by means of direction-dependent signal processing algorithms. It is often assumed here that a strongly localized useful signal component is present in the sound signal from the surroundings which is received by the hearing aid, for example in the form of contributions from a conversation partner. This useful signal component is now delimited by means of direction-dependent signals in the hearing aid from a background assumed to be a noise signal, although the noise signal can also have a considerable directional dependency. In general, the algorithms mentioned often use self-optimization, the directional characteristic of a direction-dependent signal being adapted in such a way that the influence of interference signals from the direction in which their contribution is greatest is minimized. This is usually done by minimizing the signal power of a corresponding directional signal.

In einem differenziellen Richtmikrofon erster Ordnung mit nur einem Adaptionskoeffizienten wird oftmals ein richtungsabhängiges Ausgangssignal durch eine Linearkombination eines vorwärts gerichteten Kardioids mit einem rückwärts gerichteten Kardioid erreicht. Eine Veränderung der Richtcharakteristik kann dabei über den Adaptionskoeffizienten erreicht werden, welcher den Beitrag des rückwärts gerichteten Kardioids bestimmt. Hierdurch können die Beiträge von Störgeräuschquellen, welche bezüglich der Vorwärtsrichtung des Hörgerätes in einem weiten Raumwinkelbereich liegen können, reduziert werden. Die Adaption erfolgt dabei oftmals so, dass die Energie des Ausgangssignals minimiert wird, da man annimmt, dass der Träger des Hörgerätes seine Blickrichtung zur Nutzsignalquelle hin ausrichtet, welche durch das Vorwärts-Kardioid mit konstantem Signalanteil am Ausgangssignal repräsentiert wird, und somit aus anderen Richtungen auftreffende Signale Störgeräusche sein sollen, die über den entsprechenden Anteil des Rückwärts-Kardioids unterdrückt werden.In a differential directional microphone of the first order with only one adaptation coefficient, a direction-dependent output signal is often produced by a linear combination of a forward-facing cardioid with a backward-facing one Cardioid reached. A change in the directional characteristic can be achieved via the adaptation coefficient, which determines the contribution of the backward-facing cardioid. In this way, the contributions of interference noise sources, which can lie in a wide solid angle range with respect to the forward direction of the hearing aid, can be reduced. The adaptation often takes place in such a way that the energy of the output signal is minimized, since it is assumed that the wearer of the hearing aid aligns his or her line of sight to the useful signal source, which is represented by the forward cardioid with a constant signal component in the output signal, and thus from other directions Impinging signals should be background noises that are suppressed by the corresponding portion of the backward cardioid.

Falls jedoch ein Nutzsignal nicht aus der Vorwärtsrichtung auftrifft, beispielsweise Gesprächsbeiträge eines seitlich zum Träger positionierten Sprechers, werden diese entsprechend mit abgeschwächt.However, if a useful signal does not arrive from the forward direction, for example contributions from a speaker positioned to the side of the carrier, these are correspondingly attenuated.

Die EP 2 658 2 89 A1 nennt ein Verfahren zum Steuern einer Richtcharakteristik einer Mikrofoneinrichtung in einem Hörsystem, bei dem ein erster Merkmalswert bezüglich Sprache in einem einer ersten Richtung zugeordneten ersten Signal einer Mikrofoneinrichtung und ein zweiter Merkmalswert bezüglich Sprache in einem einer zweiten Richtung zugeordneten zweiten Signal der Mikrofoneinrichtung ermittelt wird. Aus der Differenz der beiden Merkmalswerte wird ein Steuerwert gewonnen. Mit diesem Steuerwert wird die Richtcharakteristik der Mikrofoneinrichtung gesteuert.The EP 2 658 2 89 A1 calls a method for controlling a directional characteristic of a microphone device in a hearing system, in which a first feature value for speech in a first signal of a microphone device assigned to a first direction and a second feature value for speech in a second signal of the microphone device assigned to a second direction is determined. A control value is obtained from the difference between the two feature values. The directional characteristic of the microphone device is controlled with this control value.

Die DE 101 14 101 A1 nennt ein Hörgerät mit zwei Mikrofonen, in welchem Einstellparameter einer Signalverarbeitungseinheit, die die Richtcharakteristik, den Frequenzgang, die Signalanhebung, die Wahl des Hörprogrammes oder die Störgeräuschreduktion betreffen, in Abhängigkeit des Ergebnisses einer Signalanalyse der beiden Mikrofonsignale eingestellt werden. Dabei umfasst die Signalanalyse wenigstens eine Modulationsanalyse der eingehenden Signale.The DE 101 14 101 A1 calls a hearing aid with two microphones, in which setting parameters of a signal processing unit, which affect the directional characteristic, the frequency response, the signal increase, the choice of the hearing program or the noise reduction, are set depending on the result of a signal analysis of the two microphone signals. The signal analysis includes at least one modulation analysis of the incoming signals.

Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren zum Betrieb eines Hörgerätes anzugeben, durch welches ein Störgeräusch unter möglichst geringer Beeinflussung durch ein Nutzsignal unabhängig von dessen Richtung unterdrückt werden kann.The invention is therefore based on the object of specifying a method for operating a hearing aid, by means of which an interfering noise can be suppressed with the least possible influence by a useful signal, regardless of its direction.

Die Aufgabe wird erfindungsgemäß gelöst durch ein Verfahren zum Betrieb eines Hörgerätes, wobei im Hörgerät aus einem Schallsignal der Umgebung ein erstes richtungsabhängiges Signal und ein zweites richtungsabhängiges Signal erzeugt werden, wobei anhand des ersten richtungsabhängigen Signals und des zweiten richtungsabhängigen Signals ein Parameter bestimmt wird, welcher ein quantitatives Maß für eine Stationarität des Schallsignals darstellt, wobei aus dem ersten richtungsabhängigen Signal und dem zweiten richtungsabhängigen Signal anhand des Parameters ein rauschoptimiertes Signal erzeugt wird, und wobei der Parameter in einer Signal-Rückkopplungsschleife aus dem rauschoptimierten Signal bestimmt wird. Vorteilhafte und teils für sich gesehen erfinderische Ausgestaltungen sind Gegenstand der Unteransprüche und der nachfolgenden Beschreibung.The object is achieved according to the invention by a method for operating a hearing aid, with a first direction-dependent signal and a second direction-dependent signal being generated in the hearing aid from a sound signal from the environment, a parameter being determined based on the first direction-dependent signal and the second direction-dependent signal represents a quantitative measure of the stationarity of the sound signal, wherein a noise-optimized signal is generated from the first direction-dependent signal and the second direction-dependent signal based on the parameter, and the parameter is determined in a signal feedback loop from the noise-optimized signal. Advantageous and in part inventive embodiments are the subject matter of the subclaims and the following description.

Bevorzugt werden das erste richtungsabhängige Signal und das zweite richtungsabhängige Signal jeweils anhand von entsprechenden Signalen von wenigstens zwei Eingangsschallwandlern erzeugt, welche beispielsweise jeweils durch Mikrofone gegeben sein können. Unter einem richtungsabhängigen Signal ist hierbei jeweils ein Signal zu verstehen, welches eine nicht-triviale Richtcharakteristik aufweist, d.h., für einen Testschall mit konstantem Schalldruck sowie der entsprechenden Testschallquelle in konstantem Abstand zum Hörgerät weist die Empfindlichkeit gegenüber dem Testschall im jeweiligen richtungsabhängigen Signal eine messbare, bevorzugt erhebliche Richtungs- und insbesondere Winkelabhängigkeit in der Transversalebene des Trägers auf.Preferably, the first direction-dependent signal and the second direction-dependent signal are each generated on the basis of corresponding signals from at least two input sound converters, which can each be given, for example, by microphones. In this context, a direction-dependent signal is to be understood as a signal that has a non-trivial directional characteristic, that is, for a test sound with constant sound pressure and the corresponding test sound source at a constant distance from the hearing aid, the sensitivity to the test sound in the respective direction-dependent signal has a measurable, preferably considerable directional and, in particular, angular dependence in the transverse plane of the carrier.

Unter einem quantitativen Maß für eine Stationarität ist hierbei insbesondere ein Maß zu verstehen, welches einem Signal derart einen Zahlwert zuordnet, dass für einen reinen Sinuston konstanter Frequenz der Extremalwert des Maßes eingenommen wird, und bei einer zunehmenden Variation von Frequenzen von Signalanteilen eine entsprechend monotone Veränderung im Zahlwert verzeichnet. Bevorzugt können für die genannte Zuordnung dem Fachmann gängige Definitionen der Stationarität berücksichtigt werden. Der Parameter kann dabei ein absolutes quantitatives Maß darstellen, welches die Stationarität der zu überprüfenden Signale anhand einer normierten Skala bemisst, und dabei insbesondere einen festen Maximal- und einen festen Minimalwert aufweisen, oder ein relatives Maß, welches insbesondere keinen festen Extremalwert für nicht-stationäre Signale aufweist.A quantitative measure of stationarity is to be understood here in particular as a measure that assigns a numerical value to a signal in such a way that the extreme value of the measure is assumed for a pure sine tone of constant frequency, and a correspondingly monotonous change in the case of an increasing variation in frequencies of signal components recorded in the numerical value. Prefers Definitions of stationarity that are common to those skilled in the art can be taken into account for the assignment mentioned. The parameter can represent an absolute quantitative measure, which measures the stationarity of the signals to be checked using a standardized scale, and in particular have a fixed maximum and a fixed minimum value, or a relative measure, which in particular does not have a fixed extreme value for non-stationary ones Having signals.

Unter einem rauschoptimierten Signal ist insbesondere ein Signal umfasst, welches bezüglich den im Schallsignal enthaltenen Nutzsignalanteilen ein gegenüber dem ersten richtungsabhängigen Signal und gegenüber dem zweiten richtungsabhängigen Signal optimiertes SNR aufweist, falls die Nutzsignalanteile im Schallsignal von Störgeräuschanteilen überlagert sind. Insbesondere können dabei das erste richtungsabhängige Signal und das zweite richtungsabhängige Signal linear in das rauschoptimierte Signal eingehen, d.h., dass das rauschoptimierte Signal bezüglich einer zu einem bestimmten Zeitpunkt in einem der beiden richtungsabhängigen Signale eintretende Veränderung in der Zeit-Frequenz-Domäne eine lineare Antwort aufweist.A noise-optimized signal includes, in particular, a signal which, with respect to the useful signal components contained in the sound signal, has an SNR that is optimized relative to the first direction-dependent signal and relative to the second direction-dependent signal, if the useful signal components in the sound signal are superimposed by interfering noise components. In particular, the first direction-dependent signal and the second direction-dependent signal can enter the noise-optimized signal linearly, i.e. the noise-optimized signal has a linear response to a change in the time-frequency domain that occurs at a specific point in time in one of the two direction-dependent signals .

Eine in Hörgeräten übliche Vorgehensweise zur Rauschunterdrückung ist es, zunächst das erste richtungsabhängige Signal derart auszulegen, dass seine Richtung maximaler Empfindlichkeit mit der Frontalrichtung des Trägers zusammenfällt. Das zweite richtungsabhängige Signal wird nun so ausgelegt, dass einerseits seine Richtung maximaler Empfindlichkeit in eine andere Richtung als die Frontalrichtung des Trägers zeigt, und stattdessen die Richtung minimaler Empfindlichkeit mit der Frontalrichtung des Trägers zusammenfällt. Bevorzugt ist dabei für die Richtcharakteristik des zweiten richtungsabhängigen Signals die Richtcharakteristik des ersten richtungsabhängigen Signals bezüglich der Frontalebene des Trägers bei einem ordnungsgemäßen Tragen im Betrieb gespiegelt.A common procedure for noise suppression in hearing aids is first of all to interpret the first direction-dependent signal in such a way that its direction of maximum sensitivity coincides with the frontal direction of the wearer. The second direction-dependent signal is now designed so that, on the one hand, its direction of maximum sensitivity points in a direction other than the frontal direction of the wearer, and instead the direction of minimum sensitivity coincides with the frontal direction of the wearer. For the directional characteristic of the second direction-dependent signal, the directional characteristic of the first direction-dependent signal is preferably mirrored with respect to the frontal plane of the wearer when it is worn properly during operation.

Zur Unterdrückung eines Störgeräusches wird nun das erste richtungsabhängige Signal, welches vornehmlich die Sprachsignalanteile eines Gesprächspartners in Frontalrichtung aufnimmt, in Abhängigkeit von der Gesamtenergie eines resultierenden Signals mit dem zweiten richtungsabhängigen Signal überlagert. Hierbei können durch das zweite richtungsabhängige Signal Signalanteile, welche nicht aus der Frontalrichtung auf den Träger auftreffen, und somit als Störgeräusche angenommen werden, unterdrückt werden. Aufgrund des konstanten Beitrages durch das erste richtungsabhängige Signal in Frontalrichtung ist dabei für eine wirksame Unterdrückung von Störgeräuschen nur die genannte Bedingung der minimalen Gesamtenergie des aus der Überlagerung resultierenden Signales erforderlich.In order to suppress an interfering noise, the first direction-dependent signal, which primarily picks up the voice signal components of a conversation partner in the frontal direction, is now dependent on the total energy of a resultant Signal with the second direction-dependent signal superimposed. In this case, the second direction-dependent signal can suppress signal components which do not impinge on the wearer from the frontal direction and are thus assumed to be interfering noises. Because of the constant contribution by the first direction-dependent signal in the frontal direction, only the mentioned condition of the minimum total energy of the signal resulting from the superposition is required for effective suppression of interfering noises.

Dem gegenüber wird nun vorgeschlagen, anhand des ersten richtungsabhängigen Signals und des zweiten richtungsabhängigen Signals die Stationarität des Schallsignals über einen entsprechenden Parameter zu untersuchen. Dem in der Erfindung vorgeschlagenen Vorgehen liegt dabei die Überlegung zugrunde, dass stark gerichtete Störgeräusche, wie sie beispielsweise durch das Summen eines Motors oder eines Haushaltsgerätes gegeben sein können, bei einem seitlichen Auftreffen auf den Träger zwar durch das bisherige Vorgehen zufriedenstellend unterdrückt werden können, jedoch für den Fall, dass das seitlich auftreffende Signal ein Nutzsignal ist, also z.B. ein Sprachsignal eines weiteren, hinzutretenden Sprechers, ebenfalls eine Unterdrückung stattfindet, welche in diesem Fall nun unerwünscht wäre. Hierfür wird nun eine Unterscheidung zwischen einem möglichen Nutzsignal und einem möglichen Störgeräusch durchgeführt, wobei berücksichtigt wird, dass übliche Nutzsignale wie Sprache oder Musik meist eine wesentlich geringere Stationarität aufweisen als die meisten gerichteten Störgeräusche und auch als ein diffuses Hintergrundrauschen, wie es beispielsweise bei einem Gespräch mit mehreren Personen in einem Raum auftreten kann, in welchem noch weitere Gespräche erfolgen (sog. "Cocktail-Party"-Hörsituation).In contrast, it is now proposed to use the first direction-dependent signal and the second direction-dependent signal to examine the stationarity of the sound signal using a corresponding parameter. The approach proposed in the invention is based on the consideration that strongly directed interference, such as can be given for example by the hum of a motor or a household appliance, can be satisfactorily suppressed by the previous approach when hitting the carrier from the side, however in the event that the signal impinging from the side is a useful signal, that is to say, for example, a speech signal from another speaker who joins the group, a suppression also takes place, which in this case would now be undesirable. For this purpose, a distinction is made between a possible useful signal and a possible interfering noise, taking into account that common useful signals such as speech or music usually have a significantly lower stationarity than most directed interfering noises and also as a diffuse background noise, as is the case, for example, in a conversation can appear with several people in a room in which further conversations take place (so-called "cocktail party" listening situation).

Dies ermöglicht nun beispielsweise, bei einer niedrigen Stationarität das rauschoptimierte Signal derart aus den beiden richtungsabhängigen Signalen zu erzeugen, dass eine möglichst geringe direktionale Unterdrückung von Signalanteilen erfolgt, und hierdurch eventuelle, seitlich auf den Träger auftreffende Sprachsignale entsprechend nicht unterdrückt, sondern mit verstärkt werden. Im Gegenzug kann bei einer festgestellten erhöhten Stationarität unter der Annahme, dass nun erhebliche Störgeräusche vorliegen dürften, eine direktionale Unterdrückung derart erfolgen, dass das rauschoptimierte Signal vorranging nur das Sprachsignal eines Gesprächspartners umfasst, auf welchen hin bevorzugt die Richtung maximaler Empfindlichkeit des ersten richtungsabhängigen Signales auszurichten ist.This now makes it possible, for example, to generate the noise-optimized signal from the two direction-dependent signals with a low level of stationarity in such a way that the lowest possible directional suppression of signal components takes place, and as a result, any speech signals hitting the side of the carrier are not suppressed, but also amplified. In return, if there is an increased stationarity, assuming that now Considerable background noise is likely to be present, directional suppression takes place in such a way that the noise-optimized signal primarily comprises only the voice signal of a conversation partner, towards which the direction of maximum sensitivity of the first direction-dependent signal is preferably to be aligned.

Erfindungsgemäß wird der Parameter dabei in einer Signal-Rückkopplungsschleife aus dem rauschoptimierten Signal bestimmt. Während der Parameter sich rein technisch auch aus dem ersten richtungsabhängigen Signal und dem zweiten richtungsabhängigen Signal - also ohne Weiterverarbeitung zum rauschoptimierten Signal selbst - ermitteln ließe, hat eine Bestimmung des Parameters aus dem rauschoptimierten Signal den Vorteil, dass dieses Signal das für eine Weiterverarbeitung im Hörgerät vorgesehene Signal ist, als Zielgröße herangezogen werden kann. Aufwendige Umrechnungen können somit unterbleiben.According to the invention, the parameter is determined in a signal feedback loop from the noise-optimized signal. While the parameter could also be determined from the first direction-dependent signal and the second direction-dependent signal - i.e. without further processing to form the noise-optimized signal itself - from a purely technical point of view, determining the parameter from the noise-optimized signal has the advantage that this signal is what is required for further processing in the hearing aid intended signal can be used as a target variable. Complex conversions can therefore be omitted.

Als vorteilhaft erweist es sich, wenn als Parameter eine Autokorrelationsfunktion ermittelt wird. Bevorzugt ist hierbei die Autokorrelationsfunktion über ein hinsichtlich der zu erwartenden Nutzsignale und der zu erwartenden Störgeräusche geeignet zu bestimmendes Zeitfenster zu bestimmen. Der Vorteil der Verwendung der Autokorrelationsfunktion als Parameter liegt darin, dass selbige oftmals noch weitere wertvolle Informationen bietet, welche in der nachfolgenden Signalverarbeitung von Belang sein können.It proves to be advantageous if an autocorrelation function is determined as the parameter. In this case, the autocorrelation function is preferably to be determined via a time window which is to be suitably determined with regard to the expected useful signals and the expected interfering noises. The advantage of using the autocorrelation function as a parameter is that it often offers additional valuable information which can be of importance in the subsequent signal processing.

Erfindungsgemäß wird das rauschoptimierte Signal durch eine Überlagerung des ersten richtungsabhängigen Signals und des zweiten richtungsabhängigen Signals erzeugt, wobei ein Gewichtungsfaktor für die Überlagerung anhand des Parameters ermittelt wird. Dies bedeutet insbesondere, dass das rauschoptimierte Signal von der Form F + α · B ist, wobei F das erste richtungsabhängige Signal und B das zweite richtungsabhängige Signal bezeichnen, und α der anhand des Parameters bestimmte Gewichtungsfaktor ist. Diese Überlagerung ist technisch einerseits besonders einfach zu implementieren, andererseits kann hierbei das erste richtungsabhängige Signal derart ausgerichtet werden, dass die Richtung maximaler Empfindlichkeit auf einen Gesprächspartner des Trägers hin, insbesondere in Frontalrichtung hin, ausgerichtet wird, was die Ermittlung des Gewichtungsfaktors α weiter erleichtert.According to the invention, the noise-optimized signal is generated by superimposing the first direction-dependent signal and the second direction-dependent signal, a weighting factor for the superimposition being determined on the basis of the parameter. This means in particular that the noise-optimized signal is of the form F + α · B, where F denotes the first direction-dependent signal and B the second direction-dependent signal, and α is the weighting factor determined on the basis of the parameter. On the one hand, this superimposition is particularly easy to implement technically; on the other hand, the first direction-dependent signal can be aligned in such a way that the direction of maximum sensitivity to a conversation partner of the carrier, in particular is aligned in the frontal direction, which further facilitates the determination of the weighting factor α.

Bevorzugt weist hierbei das rauschoptimierte Signal für ein nicht-stationäres Schallsignal durch den Gewichtungsfaktor eine im Wesentlichen omnidirektionale Richtcharakteristik auf, und für ein maximal stationäres Schallsignal in Folge des Gewichtungsfaktors eine maximal direktionale Richtcharakteristik. Unter einer maximal direktionalen Richtcharakteristik ist hierbei insbesondere ein globales Maximum der Richtwirkung im Rahmen der zur Verfügung stehenden Richtsignale zu verstehen. Dies trägt dem Umstand Rechnung, dass für nicht-stationäre Schallsignale angenommen wird, dass keine zu unterdrückenden Störgeräusche vorliegen, hingegen jedoch möglicherweise seitlich auf den Träger auftreffende Sprachsignale vorliegen können. In diesem Fall ist eine im Wesentlichen omnidirektionale Richtcharakteristik des rauschoptimierten Signals vorteilhaft, da hierdurch Sprachsignale aus allen Raumrichtungen berücksichtigt werden können. Im Gegenzug wird für ein maximal stationäres Schallsignal angenommen, dass ein erheblicher Störgeräuschanteil vorliegt, welcher entsprechend durch eine Richtcharakteristik des rauschoptimierten Signals derart zu unterdrücken ist, dass nur noch die Raumrichtung, in welcher ein Gesprächspartner angenommen wird, also üblicherweise die Frontalrichtung, nennenswerte Signalbeiträge zum rauschoptimierten Signal liefert. Unter einer im Wesentlichen omnidirektionalen Richtcharakteristik ist hierbei insbesondere eine derartige Richtcharakteristik zu verstehen, in welcher eine Abweichung von einer perfekten Omnidirektionalität gegenüber den auftretenden Richtwirkungen insbesondere bei den direktionalen Richtcharakteristiken vernachlässigt werden kann.The noise-optimized signal preferably has an essentially omnidirectional directional characteristic for a non-stationary sound signal due to the weighting factor, and a maximum directional characteristic for a maximum stationary sound signal due to the weighting factor. A maximum directional directional characteristic is to be understood here in particular as a global maximum of the directional effect within the framework of the directional signals available. This takes into account the fact that, for non-stationary sound signals, it is assumed that there are no interfering noises to be suppressed, but that speech signals hitting the side of the carrier may be present. In this case, an essentially omnidirectional directional characteristic of the noise-optimized signal is advantageous, since this allows speech signals from all spatial directions to be taken into account. On the other hand, for a maximally stationary sound signal, it is assumed that there is a considerable amount of background noise, which is to be suppressed accordingly by a directional characteristic of the noise-optimized signal in such a way that only the spatial direction in which a conversation partner is assumed, i.e. usually the frontal direction, makes significant signal contributions to the delivers a noise-optimized signal. An essentially omnidirectional directional characteristic is to be understood here in particular as such a directional characteristic in which a deviation from perfect omnidirectionality compared to the directional effects occurring can be neglected, in particular in the case of the directional directional characteristics.

In einer weiter vorteilhaften Ausgestaltung der Erfindung wird der Parameter derart bestimmt, dass das rauschoptimierte Signal hinsichtlich des Parameters minimal ist. Dies kann insbesondere durch eine Minimierung des rauschoptimierten Signals hinsichtlich des Parameters erfolgen. Dieses Vorgehen hat den Vorteil, dass das rauschoptimierte Signal stets die geringstmögliche Stationarität und somit stets den geringstmöglichen Störgeräuschanteil aufweist.In a further advantageous embodiment of the invention, the parameter is determined in such a way that the noise-optimized signal is minimal with regard to the parameter. This can be done in particular by minimizing the noise-optimized signal with regard to the parameter. This procedure has the advantage that the noise-optimized signal always has the lowest possible stationarity and thus always the lowest possible noise component.

Zweckmäßigerweise wird das rauschoptimierte Signal bezüglich seiner Signalenergie sowie bezüglich des Parameters minimiert. Dies bedeutet insbesondere, dass das rauschoptimierte Signal, welches aus den ersten richtungsabhängigen Signal und dem zweiten richtungsabhängigen Signal gebildet wird, als Funktion der Variablen Signalenergie sowie des Parameters ein lokales Minimum aufweist. Hierdurch können insbesondere derartige Störgeräusche unterdrückt werden, welche in einer komplexen Hörsituation aus unterschiedlichen Richtungen auf den Träger auftreffen, wobei zudem ein diffuser Rauschhintergrund vorliegen mag, während die Störgeräusche selbst nur teilweise als stationär angenommen werden dürfen.The noise-optimized signal is expediently minimized with regard to its signal energy and with regard to the parameter. This means in particular that the noise-optimized signal, which is formed from the first direction-dependent signal and the second direction-dependent signal, has a local minimum as a function of the variable signal energy and the parameter. In this way, interference noises can be suppressed in particular that impinge on the wearer from different directions in a complex hearing situation, with a diffuse noise background also being present, while the interfering noises themselves may only be partially assumed to be stationary.

Erfindungsgemäß werden hierbei das erste richtungsabhängige Signal und/oder das zweite richtungsabhängige Signal anhand einer zeitverzögerten Überlagerung des ersten Mikrofonsignals mit dem zweiten Mikrofonsignal erzeugt. Bevorzugt wird hierbei für die Zeitverzögerung in der Überlagerung die akustische Laufzeitdifferenz zwischen dem ersten Mikrofon und dem zweiten Mikrofon herangezogen. Dies ist ein besonders einfach zu implementierendes und dennoch effizientes Verfahren für die Erzeugung eines richtungsabhängigen Signals, wenn die zugrundeliegenden Mikrofonsignale von richtungsunabhängigen Mikrofonen stammen.According to the invention, the first direction-dependent signal and / or the second direction-dependent signal are generated on the basis of a time-delayed superposition of the first microphone signal with the second microphone signal. The acoustic transit time difference between the first microphone and the second microphone is preferably used for the time delay in the superimposition. This is a particularly simple to implement and yet efficient method for generating a direction-dependent signal when the underlying microphone signals originate from direction-independent microphones.

Besonders bevorzugt weist hierbei das erste richtungsabhängige Signal eine Richtungsabhängigkeit in Form eines ersten Kardioids auf, welches in einer ersten Richtung ausgerichtet ist, und/oder das zweite richtungsabhängige Signal eine Richtungsabhängigkeit in Form eines zweiten Kardioids, welches in einer zweiten Richtung ausgerichtet ist. Ein kardioid-förmiges Signal zeichnet sich dadurch aus, dass die Richtung minimaler Empfindlichkeit der Richtung maximaler Empfindlichkeit entgegengesetzt ist. Dies ist beispielsweise für Signale, deren Richtcharakteristik ein Superkardioid oder ein Hyperkardioid bildet, nicht der Fall. Zudem wird ein Schallsignal aus der Richtung der minimalen Empfindlichkeit im Idealfall bei einer kardioid-förmigen Richtcharakteristik vollständig unterdrückt. Die Symmetrie zwischen der Richtung der maximalen und der minimalen Empfindlichkeit erlaubt es somit, Berechnungen für die erste und die zweite Überlagerung zur Störgeräusch-Unterdrückung besonders einfach zu halten, da zudem von der Richtung minimaler Empfindlichkeit zur Richtung maximaler Empfindlichkeit eine streng monotone Zunahme der Empfindlichkeit stattfindet. Besonders bevorzugt liegt in diesem Fall die erste Richtung der zweiten Richtung entgegengesetzt.Particularly preferably, the first direction-dependent signal has a directional dependency in the form of a first cardioid, which is oriented in a first direction, and / or the second direction-dependent signal has a directional dependency in the form of a second cardioid, which is oriented in a second direction. A cardioid-shaped signal is characterized in that the direction of minimum sensitivity is opposite to the direction of maximum sensitivity. This is not the case, for example, for signals whose directional characteristic forms a supercardioid or a hypercardioid. In addition, a sound signal from the direction of minimum sensitivity is, ideally, completely suppressed with a cardioid-shaped directional characteristic. The symmetry between the direction of the maximum and the minimum sensitivity thus allows calculations for the first and the second superimposition for noise suppression particularly easy to keep, since there is also a strictly monotonous increase in sensitivity from the direction of minimum sensitivity to the direction of maximum sensitivity. In this case, the first direction is particularly preferably opposite to the second direction.

Vor dem Hintergrund, dass in einem Richtsignal mit kardioid-förmiger Richtcharakteristik Schallsignale aus der Richtung der minimalen Empfindlichkeit im Idealfall vollständig unterdrückt werden, kann hierdurch die Berechnung der konkreten Gewichtung der beiden richtungsabhängige Signale in der Überlagerung noch weiter vereinfacht werden, da das erste richtungsabhängige Signal als eine Referenz angenommen werden kann, welche auf eine erste Nutzsignalquelle gerichtet ist, und in diesem Fall - wenn das zweite, kardioid-förmige richtungsabhängige Signal entgegen des ersten richtungsabhängigen Signals ausgerichtet ist - eine Störgeräusch-Unterdrückung durch das zweite richtungsabhängige Signal keinen Einfluss auf den Beitrag des ersten Nutzsignals hat.Against the background that in a directional signal with a cardioid-shaped directional characteristic, sound signals from the direction of minimum sensitivity are ideally completely suppressed, the calculation of the concrete weighting of the two direction-dependent signals in the superposition can be simplified even further, since the first direction-dependent signal can be assumed as a reference, which is directed to a first useful signal source, and in this case - if the second, cardioid-shaped directional signal is aligned against the first directional signal - interference noise suppression by the second directional signal has no effect on the Contribution of the first useful signal has.

Somit kann zur Bestimmung der Gewichtungen für eine möglichst effiziente Störgeräusch-Unterdrückung im Fall stationärer Signale einfach eine minimale Signalleistung im aus der Überlagerung resultierenden Signal gefordert werden, ohne dass dies einen Einfluss auf den Beitrag des ersten Nutzsignals hat. Bevorzugt wird hierfür zunächst die Überlagerung anhand der minimalen Signalleistung gebildet, anschließend für das resultierende Signal der quantitative Parameter für die Stationarität ermittelt, und nun anhand des Parameters, insbesondere iterativ, die Gewichtung in der Überlagerung so lange angepasst, bis der Parameter minimal ist, so dass das resultierende Signal eine bezogen auf den Parameter minimale Stationarität aufweist.Thus, to determine the weightings for the most efficient possible interference noise suppression in the case of stationary signals, a minimum signal power can simply be required in the signal resulting from the superposition, without this having an influence on the contribution of the first useful signal. For this purpose, the superimposition is preferably first formed using the minimum signal power, then the quantitative parameter for the stationarity is determined for the resulting signal, and the weighting in the superimposition is now adjusted, in particular iteratively, using the parameter until the parameter is minimal, see above that the resulting signal has a minimum stationarity in relation to the parameter.

Die Erfindung nennt weiter ein Hörgerät mit einem ersten Mikrofon und einem zweiten Mikrofon zur Erzeugung eines ersten richtungsabhängigen Signals und eines zweiten Richtungsabhängigen Signals, welches dazu eingerichtet ist, das vorbeschriebene Verfahren durchzuführen. Insbesondere werden hierbei das ersten richtungsabhängige Signal und das zweite richtungsabhängige Signal jeweils mittels sowohl des ersten Mikrofons als auch des zweiten Mikrofons erzeugt. Bevorzugt erfolgt die Durchführung des Verfahrens im Betrieb des Hörgerätes mittels einer Steuereinheit, welche besonders bevorzugt als Teil der Signalverarbeitungseinheit, in welcher sämtliche weiteren Funktionen der Signalverarbeitung implementiert sind, ausgebildet ist. Die für das Verfahren und für seine Weiterbildungen angegebenen Vorteile können sinngemäß auf das Hörgerät übertragen werden.The invention also mentions a hearing aid with a first microphone and a second microphone for generating a first direction-dependent signal and a second direction-dependent signal, which is set up to carry out the method described above. In particular, the first direction-dependent signal and the second direction-dependent signal are each generated by means of both the first microphone and the second microphone. Prefers the method is carried out during operation of the hearing aid by means of a control unit which is particularly preferably designed as part of the signal processing unit in which all further functions of the signal processing are implemented. The advantages specified for the method and for its developments can be applied analogously to the hearing aid.

Nachfolgend wird ein Ausführungsbeispiel der Erfindung anhand einer Zeichnung näher erläutert. Hierbei zeigen jeweils schematisch:

Fig. 1
in einer Draufsicht die Abschwächung eines gerichteten Störsignals mittels einer Überlagerung zweier Richtsignale in einem Hörgerät, und
Fig. 2
in einem Blockdiagramm den Ablauf eines Verfahrens zur Abschwächung von Störsignalen in einem Hörgerät bei gleichzeitiger Anwesenheit von Nutzsignalen aus unterschiedlichen Richtungen.
An exemplary embodiment of the invention is explained in more detail below with reference to a drawing. The following are shown schematically in each case:
Fig. 1
in a plan view the attenuation of a directional interference signal by means of a superposition of two directional signals in a hearing aid, and
Fig. 2
in a block diagram the sequence of a method for attenuating interference signals in a hearing aid with the simultaneous presence of useful signals from different directions.

Einander entsprechende Teile und Größen sind in allen Figuren jeweils mit gleichen Bezugszeichen versehen.Corresponding parts and sizes are provided with the same reference symbols in each of the figures.

In Fig. 1 ist schematisch in einer Draufsicht ein Träger 1 eines Hörgerätes 2 gezeigt. Der Trägers 1 befindet sich hierbei in einer Gesprächssituation mit einem Gesprächspartner 4, der bzgl. des Trägers 1 in dessen Frontalrichtung 6 positioniert ist. In nicht näher dargestellter Weise werden nun im Hörgerät 2 ein erstes richtungsabhängiges Signal 8f (gestrichelte Linie) und ein zweites richtungsabhängiges Signal 8r (gepunktete Linie) gebildet, deren Richtcharakteristik jeweils durch ein Kardioid gegeben ist. Die Kardioid-förmige Richtcharakteristik des ersten richtungsabhängigen Signals 8f hat zur Folge, dass für Schallsignale aus der Frontalrichtung 6 eine maximale Empfindlichkeit vorliegt und somit Schallsignale aus dieser Richtung maximal in das erste richtungsabhängige Signal 8f eingehen, während Schallsignale aus der zur Frontalrichtung 6 entgegengesetzten Rückwärtsrichtung 10 idealerweise im ersten richtungsabhängigen Signal 8f vollständig unterdrückt werden. Das zweite richtungsabhängige Signal 8r weist eine zum ersten richtungsabhängigen Signal 8f entgegengesetzte Richtungsabhängigkeit auf, sodass in das zweite richtungsabhängige Signal 8r Schallsignale aus der Rückwärtsrichtung 10 maximal eingehen, während Schallsignale aus der Frontalrichtung 6 idealerweise vollständig unterdrückt werden.In Fig. 1 a wearer 1 of a hearing aid 2 is shown schematically in a plan view. The carrier 1 is in a conversation situation with a conversation partner 4 who is positioned in the frontal direction 6 of the carrier 1. In a manner not shown, a first direction-dependent signal 8f (dashed line) and a second direction-dependent signal 8r (dotted line) are now formed in the hearing aid 2, the directional characteristics of which are each given by a cardioid. The cardioid-shaped directional characteristic of the first direction-dependent signal 8f has the consequence that there is a maximum sensitivity for sound signals from the frontal direction 6 and thus sound signals from this direction enter the first direction-dependent signal 8f at a maximum, while sound signals from the reverse direction 10 opposite to the frontal direction 6 ideally be completely suppressed in the first direction-dependent signal 8f. The second direction-dependent signal 8r has one to the first direction-dependent signal 8f on opposite directional dependence, so that in the second direction-dependent signal 8r sound signals from the rearward direction 10 enter maximally, while sound signals from the frontal direction 6 are ideally completely suppressed.

Die Gesprächssituation des Trägers 1 mit dem Gesprächspartner 4 wird nun hierbei überlagert von verschiedenen Störgeräuschen 12a, 12b, wobei 12a und 12b stark direktionale Störgeräusche sind, welche also jeweils von einer lokalisierbaren Quelle wie z.B. einem Motor oder einem elektrischen Haushaltsgerät emittiert werden.The conversation situation of the carrier 1 with the conversation partner 4 is now superimposed by various interfering noises 12a, 12b, with 12a and 12b being strongly directional interfering noises, which are thus each emitted by a localizable source such as a motor or an electrical household appliance.

Zur Bereinigung des Sprachsignals 13 des Gesprächspartners 4 von den Störgeräuschen 12a, 12b werden nun im Hörgerät 2 durch eine Überlagerung des ersten richtungsabhängigen Signals 8f mit dem zweiten richtungsabhängigen Signal 8r der Form F + α · B abgeschwächt, wobei F und B das erste bzw. zweite richtungsabhängige Signal 8f, 8r sind und α ein entsprechend zu wählender Gewichtungsfaktor ist. Hierbei wird ausgenutzt, dass die Nutzsignalquelle, also hier der Gesprächspartner 4, als in Frontalrichtung 6 angenommen wird, und somit ihre Beiträge im zweiten richtungsabhängigen Signal 8r vollständig unterdrückt werden, und deshalb nur durch das erste richtungsabhängige Signal 8f in das aus der Überlagerung resultierende Signal F + α B Eingang finden. Der Beitrag des zweiten richtungsabhängigen Signals 8r ist somit im resultierenden Signal so über den Gewichtungsfaktor α anzupassen, dass das resultierende Signal einen minimalen Signalpegel aufweist, da nicht zuletzt infolge des bei einer Variation von α unveränderlichen Beitrages des Nutzsignals aus der Frontalrichtung 6 (s.o.) sicher gestellt wird, dass die Abschwächung der Signalkomponenten, welche nicht aus der Frontalrichtung 6 kommen, maximal ist.In order to clean the speech signal 13 of the interlocutor 4 from the interfering noises 12a, 12b are now attenuated in the hearing aid 2 by superimposing the first direction-dependent signal 8f with the second direction-dependent signal 8r of the form F + α · B, where F and B are the first or second direction-dependent signals 8f, 8r and α is a weighting factor to be selected accordingly. This makes use of the fact that the useful signal source, i.e. here the interlocutor 4, is assumed to be in the frontal direction 6, and thus its contributions are completely suppressed in the second direction-dependent signal 8r, and therefore only by the first direction-dependent signal 8f in the signal resulting from the superimposition F + α B find entrance. The contribution of the second direction-dependent signal 8r is thus to be adjusted in the resulting signal using the weighting factor α so that the resulting signal has a minimum signal level, not least because of the unchangeable contribution of the useful signal from the frontal direction 6 (see above) due to the unchangeable contribution of the useful signal from the frontal direction 6 (see above) it is set that the attenuation of the signal components, which do not come from the frontal direction 6, is maximal.

Tritt nun ein weiterer Sprecher 14 hinzu, dessen Sprachsignal 16 nicht aus der Frontalrichtung 6, sondern aus einer seitlichen Richtung beim Träger 1 auftrifft, so würde zunächst die eben beschriebene Vorgehensweise dafür sorgen, dass das Sprachsignal 16 wie die Störgeräusche 12a, 12b behandelt und entsprechend unterdrückt wird. Um dies zu vermeiden, wird eine Erkennung vorgenommen, ob es sich bei den seitlich auftreffenden Geräuschen 12a, 12b, 16 um Störgeräusche oder um potentielle Nutzsignale handelt, und nur die Störgeräusche 12a, 12b unterdrückt. Dies ist anhand von Fig. 2 beschrieben.If a further speaker 14 comes in, whose speech signal 16 does not come from the frontal direction 6, but from a lateral direction at the wearer 1, the procedure just described would initially ensure that the speech signal 16 is treated like the background noises 12a, 12b and accordingly is suppressed. To avoid this, a detection is made as to whether the laterally incident noises 12a, 12b, 16 are interference noises or potential useful signals, and only the interference noises 12a, 12b are suppressed. This is based on Fig. 2 described.

In Fig. 2 ist mittels eines Blockschaltbildes ein Verfahren 20 zur direktionalen Rauschunterdrückung im Hörgerät 2 dargestellt. Im Hörgerät 2 wird aus dem Schallsignal 22 der Umgebung mittels eines ersten Mikrofons 24a ein erstes Mikrofonsignal 26a erzeugt, und mittels eines zweiten Mikrofons 24b ein zweites Mikrofonsignal 26b erzeugt. Das zweite Mikrofonsignal 26b wird hierbei einerseits um das Zeitintervall T verzögert, sodass hierdurch ein zeitverzögertes zweites Mikrofonsignal 28b gebildet wird, welches vom ersten Mikrofonsignal 26a subtrahiert wird, sodass hierdurch das erste richtungsabhängige Signal 8f gebildet wird. Auf gleiche Weise wird das erste Mikrofonsignal 26a zusätzlich um das Zeitintervall T verzögert, und hierdurch das erste zeitverzögerte Mikrofonsignal 28a gebildet, welches vom zweiten Mikrofonsignal 26b subtrahiert wird und hierdurch das zweite richtungsabhängige Signal 8r gebildet wird. Das erste richtungsabhängige Signal 8f und das zweite richtungsabhängige Signal 8r weisen hierbei jeweils die kardioid-förmigen Richtcharakteristiken gemäß Fig. 1 auf.In Fig. 2 a method 20 for directional noise suppression in hearing aid 2 is shown by means of a block diagram. In the hearing aid 2, a first microphone signal 26a is generated from the sound signal 22 of the surroundings by means of a first microphone 24a, and a second microphone signal 26b is generated by means of a second microphone 24b. The second microphone signal 26b is delayed by the time interval T, so that a time-delayed second microphone signal 28b is formed, which is subtracted from the first microphone signal 26a, so that the first direction-dependent signal 8f is formed. In the same way, the first microphone signal 26a is additionally delayed by the time interval T, thereby forming the first time-delayed microphone signal 28a, which is subtracted from the second microphone signal 26b and thereby forming the second direction-dependent signal 8r. The first direction-dependent signal 8f and the second direction-dependent signal 8r each have the cardioid-shaped directional characteristics according to FIG Fig. 1 on.

In einer Überlagerung 30 der Form F + α · B wird nun ein Gewichtungsfaktor α derart bestimmt, dass das aus der Überlagerung 30 resultierende Signal 32 eine minimale Stationarität aufweist. Hierfür wird das resultierende Signal 32 einer Signal-Rückkopplungsschleife 34 zugeführt, und dort ein Parameter 36 für die Stationarität der Signalanteile ermittelt. Der Parameter 36 kann beispielsweise gegeben sein durch eine Autokorrelationsfunktion, welche über ein geeignet zu wählendes Zeitfenster zu berechnen ist.In a superposition 30 of the form F + α · B, a weighting factor α is now determined in such a way that the signal 32 resulting from the superposition 30 has a minimum stationarity. For this purpose, the resulting signal 32 is fed to a signal feedback loop 34, where a parameter 36 for the stationarity of the signal components is determined. The parameter 36 can be given, for example, by an autocorrelation function which is to be calculated over a suitable time window to be selected.

Wird nun festgestellt, dass das zu einem Gewichtungsfaktor α resultierende Signal 32 eine hinsichtlich des Parameters 36 eine minimale Stationarität aufweist, d.h., dass der Parameter 36 für die vorliegende Überlagerung 30 ein lokales Minimum einnimmt, so wird in der Signal-Rückkopplungsschleife 34 die Überlagerung 30 nicht weiter verändert. Wird jedoch in der Signal-Rückkopplungs-Schleife 34 festgestellt, dass das resultierende Signal 32 einen Stationaritäts-Parameter 36 aufweist, welcher nicht minimal ist, z.B. anhand einer Betrachtung der Monotonie des Parameters 36 bei geringen Variationen von α um den vorliegenden Wert, so wird der Gewichtungsfaktor α in der Überlagerung 30 dahingehend angepasst, dass der Parameter 36 minimiert wird. Dies kann insbesondere interaktiv geschehen. Auch ist ein Parameter 36 denkbar, welcher ein absolutes Maß für Stationarität liefert, und dabei insbesondere geeignet normiert ist, so dass anhand des Wertes Parameters 36 zu einer vorliegenden Überlagerung mit einem Gewichtungsfaktor α und anhand des entsprechenden Abstands des Wertes des Parameters 36 vom Minimalwert auch eine quantitative Aussage über die notwendige Anpassung des Gewichtungsfaktors α möglich wird.If it is now found that the signal 32 resulting in a weighting factor α has a minimum stationarity with regard to the parameter 36, that is to say that the parameter 36 assumes a local minimum for the present superposition 30, then the superposition 30 becomes in the signal feedback loop 34 not changed any further. If, however, it is determined in the signal feedback loop 34 that the resulting signal 32 has a stationarity parameter 36 which is not minimal, for example on the basis of a consideration of the monotony of the parameter 36 with small variations of α around the present value, the weighting factor α in the overlay 30 is adapted to the effect that the parameter 36 is minimized. In particular, this can be done interactively. A parameter 36 is also conceivable, which provides an absolute measure of stationarity and is in particular suitably normalized so that based on the value of parameter 36 for an overlay with a weighting factor α and based on the corresponding distance between the value of parameter 36 and the minimum value a quantitative statement about the necessary adjustment of the weighting factor α becomes possible.

Liegen beispielsweise in der Gesprächssituation nach Fig. 1 nur das Sprachsignal 13 des Gesprächspartners 4 sowie die beiden Störgeräusche 12a, 12b vor, so ist das Sprachsignal hierbei nicht-stationär, während die beiden Störgeräusche 12a, 12b hochgradig stationär sind. Für die Überlagerung 30 ist der Gewichtungsfaktor α derart zu bestimmen, dass in F + α · B die Signalanteile der Störgeräusche 12a, 12b über das zweite richtungsabhängige Signal B möglichst eliminiert werden. Dies erfolgt durch einen negativen Gewichtungsfaktor α vom Betrag <1. In diesem Fall entspricht das resultierende Signal 32 im Wesentlichen demjenigen Signal, welches man auch durch eine Minimierung der Signalenergie erreichen würde, da das Sprachsignal 13, welches durch F in das resultierende Signal 32 eingeht, nicht-stationär ist, und seine Signalanteile durch die Korrekturen der stationären Signalanteile mittels des Signals B nicht beeinträchtigt werden.Lags behind in the conversation situation, for example Fig. 1 If only the speech signal 13 of the interlocutor 4 and the two interfering noises 12a, 12b are present, then the speech signal is non-stationary, while the two interfering noises 12a, 12b are highly stationary. For the superimposition 30, the weighting factor α is to be determined in such a way that the signal components of the interference noises 12a, 12b via the second direction-dependent signal B are eliminated as far as possible in F + α · B. This is done using a negative weighting factor α with an amount <1. In this case, the resulting signal 32 essentially corresponds to the signal that would also be achieved by minimizing the signal energy, since the speech signal 13, which enters the resulting signal 32 through F, is non-stationary, and its signal components are due to the corrections of the stationary signal components are not impaired by means of the signal B.

Liegen andererseits in der Gesprächssituation nach Fig. 1 nur das Sprachsignal 13 des Gesprächspartners 4 sowie das Sprachsignal 16 des Gesprächspartners 14 vor, würde eine Überlagerung 30, welche auf einer Minimierung der Energie des resultierenden Signals 32 basiert, das Sprachsignal 16 des Gesprächspartners 14 erheblich unterdrücken, was unerwünscht ist. Da jedoch die Bestimmung des Gewichtungsfaktors α nicht auf einer Minimierung der Energie des resultierenden Signals 32, sondern auf einer Minimierung seiner Stationarität - gemessen am Parameter 36 - beruht, werden in F + α · B die Signale weitgehend addiert, wodurch sich eine weitgehend omnidirektionale Richtcharakteristik für das resultierende Signal 32 ergibt.On the other hand, they lag behind in the conversation Fig. 1 If only the voice signal 13 of the interlocutor 4 and the voice signal 16 of the interlocutor 14 are present, an overlay 30 based on minimizing the energy of the resulting signal 32 would significantly suppress the voice signal 16 of the interlocutor 14, which is undesirable. However, since the determination of the weighting factor α is not based on a minimization of the energy of the resulting signal 32, but on a minimization of its stationarity - as measured by the parameter 36 - the signals are largely added in F + α · B, which results in a largely omnidirectional directional characteristic for the resulting signal 32.

Durch die zusätzlichen Beiträge des Sprachsignals 14 im Signal B wird im resultierenden Signal 32 die ohnehin schon geringe Stationarität des Sprachsignals13 infolge der unterschiedlichen Gesprächspartner 4, 14 und somit der unterschiedlichen spektralen Beiträge noch weiter reduziert. Der Gewichtungsfaktor α ist nun positiv, und so ausgelegt, dass er die Abschwächung des Sprachsignals 16 durch die seitliche Abschwächung der Richtcharakteristik des ersten richtungsabhängigen Signals 8f möglichst kompensiert.Due to the additional contributions of the speech signal 14 in the signal B, the already low stationarity of the speech signal 13 due to the different interlocutors 4, 14 and thus the different spectral contributions is reduced even further in the resulting signal 32. The weighting factor α is now positive and is designed in such a way that it compensates as far as possible for the attenuation of the speech signal 16 due to the lateral weakening of the directional characteristic of the first direction-dependent signal 8f.

Falls in der Gesprächssituation nach Fig. 1 beide Sprachsignale 13, 16 und beide Störgeräusche 12a, 12b vorliegen, wird die Minimierung der Stationarität des resultierenden Signals 32 dazu führen, dass einerseits die stationären Störgeräusche 12a, 12b möglichst geringe Beiträge zum resultierenden Signal 32 liefern, andererseits das nicht-stationäre Sprachsignal 16 möglichst wenig unterdrückt wird. Da nur ein Freiheitsgrad - der Gewichtungsfaktor α - zur Verfügung steht, ist dies nur mit Einschränkungen möglich, das resultierende Signal 32 ist hinsichtlich der Signalenergie nicht mehr minimal in a, jedoch wird dies angesichts der komplexen Gesprächssituation in Kauf genommen, um nicht das Sprachsignal 16 unerwünschterweise zu unterdrücken.If in the conversation situation after Fig. 1 Both speech signals 13, 16 and both interfering noises 12a, 12b are present, the minimization of the stationarity of the resulting signal 32 will result in the stationary interfering noises 12a, 12b contributing as little as possible to the resulting signal 32 on the one hand, and the non-stationary speech signal 16 on the other hand being as small as possible is little suppressed. Since only one degree of freedom - the weighting factor α - is available, this is only possible with restrictions, the resulting signal 32 is no longer minimal in a with regard to the signal energy, but this is accepted in view of the complex conversation situation, not the speech signal 16 undesirably suppress.

Durch das beschriebene Vorgehen werden einerseits Störgeräusche der Form 12a, 12b unterdrückt, hingegen nicht die Signalanteile des Sprachsignals 16, sodass das aus der Überlagerung resultierende Signal 32 ein rauschoptimiertes Signal ist.Through the procedure described, on the one hand interfering noises of the form 12a, 12b are suppressed, on the other hand not the signal components of the speech signal 16, so that the signal 32 resulting from the superposition is a noise-optimized signal.

Obwohl die Erfindung im Detail durch das bevorzugte Ausführungsbeispiel näher illustriert und beschrieben wurde, ist die Erfindung nicht durch dieses Ausführungsbeispiel eingeschränkt. Andere Variationen können vom Fachmann hieraus abgeleitet werden, ohne den Schutzumfang der Erfindung zu verlassen.Although the invention has been illustrated and described in more detail by the preferred exemplary embodiment, the invention is not restricted by this exemplary embodiment. Other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.

BezugszeichenlisteList of reference symbols

11
Trägercarrier
22
HörgerätHearing aid
44th
GesprächspartnerInterlocutor
66th
FrontalrichtungFrontal direction
8f8f
erstes richtungsabhängiges Signalfirst directional signal
8r8r
zweites richtungsabhängiges Signalsecond directional signal
1010
RückwärtsrichtungReverse direction
12a, b12a, b
StörgeräuschBackground noise
1313th
SprachsignalVoice signal
1414th
GesprächspartnerInterlocutor
1616
SprachsignalVoice signal
2020th
VerfahrenProcedure
2222nd
SchallsignalSound signal
24a/b24a / b
erstes/zweites Mikrofonfirst / second microphone
26a/b26a / b
erstes/zweites Mikrofonsignalfirst / second microphone signal
28a/b28a / b
erstes/zweites zeitverzögertes Mikrofonsignalfirst / second time-delayed microphone signal
3030th
ÜberlagerungOverlay
3232
resultierendes/rauschoptimiertes Signalresulting / noise-optimized signal
3434
Signal-RückkopplungsschleifeSignal feedback loop
3636
Parameterparameter
TT
ZeitintervallTime interval

Claims (7)

  1. A method for operating a hearing device (2),
    wherein in the hearing device (2), a first direction-dependent signal (8f) and a second direction-depending signal (8r) are generated from a sound signal (22) of the environment,
    wherein in the hearing device (2), from the sound signal (22), a first microphone signal (26a) is generated by a first microphone (24a), and a second microphone signal (26b) is generated by a second microphone (24b),
    wherein the first direction-dependent signal (8f) and/or the second direction-dependent signal (8r) are generated by means of a time-delayed superposition of the first microphone signal (26a) with the second microphone signal (26b), respectively, wherein by means of the first direction-dependent signal (8f) and the second direction - dependent signal (8r), a parameter is determined, which represents a quantitative measure for a stationarity of the sound signal (22),
    characterized in that a noise-optimized signal (32) is generated from the first direction-dependent signal (8f) and the second direction-dependent signal (8r) by means of the parameter (36), the parameter (36) is determined in a signal feedback loop (34) from the noise-optimized signal (32),
    the noise-optimized signal (32) is generated by a superposition of the first direction-dependent signal (8f) and the second direction-dependent signal (8r), and a weighting factor for the superposition is ascertained by means of the parameter (36), wherein the noise-optimized signal (32) is composed by a superposition of the first direction-dependent signal (8f) and the second direction-dependent signal (8r), the latter being multiplied with the weighting factor, and, wherein the weighting factor is determined such that the noise-optimized signal (32) has a minimal stationarity.
  2. The method according to claim 1,
    wherein as the parameter (36), an autocorrelation function is ascertained.
  3. The method according to claim 1 or claim 2,
    wherein for a non-stationary sound signal (13, 16), the noise-optimized signal (32) shows an essentially omni-directional directivity characteristic due to the weighting factor, and
    wherein for a maximally stationary sound signal (12a, 12b), the noise-optimized signal (32) shows a maximally directional directivity characteristic due to the weighting factor.
  4. The method according to one of the preceding claims,
    wherein the weighting factor is determined such that the noise-optimized signal (32) is minimal with respect to its signal energy as well as with respect to the parameter (36).
  5. The method according to one of the preceding claims,
    wherein the first direction-dependent signal (8f) shows a directional dependence in the shape of a first cardioid aligned in a first direction (6), and/or
    wherein the second direction-dependent signal (8r) shows a directional dependence in the shape of a second cardioid aligned in a second direction (10).
  6. The method according to claim 5,
    wherein the first direction (6) is opposite to the second direction (10).
  7. A hearing device (2) with a first microphone (24a) and a second microphone (24b) for generating a first direction-dependent signal (8f) and a second direction-dependent signal (8r), respectively, the hearing device (2) being configured to perform the method according to one of the preceding claims.
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