The invention relates to a method for operating a hearing apparatus comprising a first and a second omnidirectional microphone and an associated hearing apparatus specified with directional effect.
The speech behavior in an interference noise-filled environment is a frequently known problem of the hard-of-hearing, who require a high signal-to-noise ratio of up to 10 dB here in order to achieve the same speech intelligibility as a person with normal hearing. Moreover, the natural directional effect of the outer ear gets lost in the case of a supply with behind-the-ear hearing devices. The rehabilitation with hearing devices is therefore not only to include the individual compensation of the hearing loss by means of amplification and dynamic compression but instead also the reduction of interference noises in order to effect a significant improvement in the speech intelligibility in situations with interference noise. Modem digital hearing devices have interference noise suppression methods, which satisfy the hearing device-specific requirements in respect of efficiency, sound quality and artifact freedom.
Directional microphone systems rank here among the interference noise suppression methods established years ago and subsequently result in improving the speech intelligibility in hearing situations, in which the useful signal and the interference noise signals come from different directions. In modern hearing devices, the directional effect is generated by differentially processing two or more adjacent microphones with omnidirectional characteristics.
The disadvantage of directional microphone systems is that in the case of high amplification these are unstable as a result of feedback. Generally the amplification can be selected to be greater when using omnidirectional microphones, thereby being advantageous particularly in the case of extreme hearing difficulties.
DE 102 49 416 A1 specifies a method for adjusting and operating a hearing aid device which can be worn on the body of a test person comprising a microphone system arranged outside the auditory canals of the test person when the hearing aid device is being worn.
DE 698 03 933 T2 specifies an arrangement and a method for embodying a predetermined amplification characteristic as a function of the direction, from which the acoustic signals are received. To this end, delays in acoustic signals are determined relative to one another.
DE 603 16 474 T2 also specifies a method and a microphone system for providing a directional response, with an output signal being minimized in terms of energy.
CH 693 759 A5 also specifies an apparatus and a method for suppressing interference noises, with an output signal being formed from two microphones by means of filtering and wiring.
It is the object of the invention to specify a method for operating a hearing apparatus as well as a hearing apparatus, which enables a directional effect even when using omnidirectional microphone signals.
According to the invention, the set object is achieved with the method and the hearing apparatus of the independent claims.
The invention claims a method for operating a hearing apparatus comprising a first and a second microphone which can be shielded against certain directions. The microphones emit a first and/or a second microphone signal. The first and the second microphone indicate a different directional effect. The method includes the following steps:
This is advantageous in that a higher stability of omnidirectional microphones is combined with a directionally-dependent signal processing.
In one development, the directional effect can be effected by shielding against ambient sound. As a result, a microphone directional effect can be generated without additional measures.
In a further embodiment, as a result of the different shielding from the first microphone, the ambient sound can be predominantly recorded from the front and from the second microphone the ambient sound can be predominantly recorded from the rear. This enables speech to be identified from the front during the signal processing for instance.
The method may also comprise the following steps:
This is advantageous in that the omnidirectional signal is amplified in a frequency-dependent fashion as a function of the original direction of the processed signal.
The hearing apparatus can also include at least a third microphone emitting a third microphone signal. As a result, body microphones and hearing device microphones can be combined.
In one development, the method can include the following steps:
In one advantageous embodiment, the frequency-dependent amplification can be determined from a difference of the first and the second microphone signal. Sound from the front and sound from the rear can be separated in this way for instance.
The invention also specifies a hearing apparatus comprising a first and a second microphone emitting a first and a second microphone signal. The first and the second microphone have different directional effects. The two microphone signals can be transformed by a Fast Fourier Transformation or a filter bank into the frequency range and a frequency-dependent amplification can be determined for an output signal of the hearing apparatus from the two microphone signals transformed in the frequency range.
In one development, the directional effect can be achieved by shielding in respect of ambient sound.
In one further embodiment, as a result of the different shielding, the first microphone can receive the ambient sound predominantly from the front and the second microphone can receive the ambient sound predominantly from the rear.
The output signal can advantageously be formed from the first and/or the second microphone signal and the output signal can be amplified with the frequency-dependent amplification.
The hearing apparatus can also be embodied as a behind-the-ear hearing device, with the two microphones being arranged in the behind-the-ear hearing device.
In one further embodiment, the different shielding can be achieved by means of an outer ear shading.
In a preferred embodiment, the first and the second microphone can be embodied as body microphones and the hearing apparatus can include a hearing device with at least one third microphone emitting a third microphone signal.
The output signal can also be formed from the at least one third microphone signal and the output signal can be amplified with the frequency-dependent amplification.
The different shielding can be effected by the body of a hearing device wearer in one further embodiment.
In one development, the first and the second microphone can each include a radio transmitter facility, which transmits a frequency-dependent level information to the hearing device for determining the frequency-dependent amplification. Bandwidth-saving data can be transmitted as a result.
In one advantageous configuration, the first and the second microphone can be located in different hearing devices and the hearing devices can each include a radio transmitter facility, which transmits a frequency-dependent level information to the other hearing device in order to determine the frequency-dependent amplification. This is advantageous in that no additional body microphones are needed.
Further details and advantages of the invention are apparent from the subsequent explanations of several exemplary embodiments on the basis of schematic drawings, in which;
The signal of the third microphone 13 of the hearing device 6 is broken down in a second filter bank into its frequency components and is fed to an additional input of the multiplier 18. A frequency-independent amplification factor reaches the multiplier 18 from a basic amplification unit 17, for instance volume controller, by way of an additional input of the multiplier 18. The signal of the third microphone 13 is now amplified in the multiplier 18 according to the amplification factor and the amplified signal is then fed to an inverse Fourier transformation. The output signal converted into the time region is fed to an input of a receiver 12. The electrical signals are converted there into acoustic signals. A sound signal with directional information is thus made available to a hearing device user.
Mathematically, the method proceeding in the apparatus according to
The equations
S1(t)S1(t,n) (1)
S2(t)S2(t,n) (2)
S3(t)S3(t,n) (3)
describe a breakdown of three microphone signals by means of a filter bank, for instance similarly to filtering in the hearing device, into several channels, indicated by the frequency parameter n.
The frequency-transformed first and second microphone signals are transformed into frequency-dependent level information (e.g. by means of low pass filtering):
L
1(t,n)=Level{S1(t,n)} (4)
L
2(t,n)=Level{S2(t,n)} (5)
A frequency-dependent amplification g( ) is determined from the thus determined level information, said amplification being multiplied together with a basic amplification gain ( ) with the third microphone signal S3(t)
S
A(t,n)=S3(t,n){gain(n)+g[L1(t,n),L2(t,n)]}. (6)
The output signal SA(t) is then determined by recovery from the individual channel signals SA(t,n).
In one configuration of the invention, the weighting of the frequency-dependent amplification can be matched to the long time spectrum of speech. Speech-relevant signal parts arriving from the front can as a result be more easily detected.
In a further embodiment, the use of additional, external microphones can be avoided. To this end, level information is exchanged between a left and a right hearing device. As a result, laterally arriving sound can be detected. In
Number | Date | Country | Kind |
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10 2008 046 040.0 | May 2008 | DE | national |
This application claims priority of German application No. 10 2008 046 040.0 filed Sep. 5, 2008, and the provisional patent application 61/095,326 filed on Sep. 9, 2008. All of the priority applications are incorporated by reference herein in their entirety.
Number | Date | Country | |
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61095326 | Sep 2008 | US |