Method for operating a hearing device, and hearing device
A method operates a hearing device. The hearing device has a microphone by which ambient sound is picked up and is converted into an input signal that has a wanted component and a noise component. A stationarity of the input signal is determined. A signal-to-noise ratio of the input signal is determined on a basis of a scaling factor. The scaling factor is determined on a basis of the stationarity, namely on a basis of a function that indicates the scaling factor on a basis of the stationarity of the input signal. A corresponding hearing device implements such a method.
1. A method for operating a hearing device having a microphone, which comprises the steps of:
picking up and converting an ambient sound into an input signal having a wanted component and a noise component via the microphone;
determining a stationarity of the input signal; and
determining a signal-to-noise ratio of the input signal on a basis of a scaling factor, wherein the scaling factor is determined on a basis of the stationarity, namely on a basis of a function that indicates the scaling factor on a basis of the stationarity of the input signal.
2. The method according to claim 1 , which further comprises:
measuring an input level of the input signal;
determining an estimated noise component of the input signal and the estimated noise component is multiplied by the scaling factor, so that a scaled, estimated noise component is obtained; and
calculating the signal-to-noise ratio by virtue of a difference being formed from the input level and the scaled, estimated noise component and by virtue of the signal-to-noise ratio being calculated as a ratio of a difference to the scaled, estimated noise component.
3. The method according to claim 2 , wherein the hearing device has a first level meter and a second level meter, and the method further comprises the steps of:
using the first level meter to determine the input level; and
using a second level meter to determine the estimated noise component.
4. The method according to claim 3 , which further comprises determining the estimated noise component using the second level meter that is operated with two asymmetric time constants.
5. The method according to claim 4 , wherein the second level meter is operated with an attack that is longer than a release of the second level meter.
6. The method according to claim 1 , wherein the function is in a form such that a greater scaling factor is determined when the stationarity is greater.
7. The method according to claim 1 , wherein the function is predefined by means of a calibration measurement that involves an actual signal-to-noise ratio being determined for different ratios of the wanted component and the noise component and the actual signal-to-noise ratio being compared with a calculated signal-to-noise ratio.
8. The method according to claim 1 , wherein the function for the scaling factor is adapted on a basis of the stationarity of the noise component.
9. The method according to claim 8 , which further comprises determining the stationarity of the noise component by virtue of temporal dynamics of the input signal being analyzed.
10. The method according to claim 8 , which further comprising selecting the function for the scaling factor from at least two basic functions on a basis of the stationarity of the noise component.
11. The method according to claim 8 , wherein there are two basic functions available and the function is determined by virtue of the two basic functions being mixed with one another in a mix ratio that is dependent on the stationarity of the noise component.
12. The method according to claim 1 , wherein the hearing device has multiple frequency channels, and the method further comprises calculating the signal-to-noise ratio for each frequency channel from a partial number of the frequency channels, so that multiple signal-to-noise ratios are obtained, from which a mean value is then formed that is an averaged signal-to-noise ratio.
13. The method according to claim 1 , wherein:
an operating parameter of the hearing device is adjusted on a basis of the signal-to-noise ratio; and
the operating parameter is a parameter of a beamformer or a parameter of a noise reduction system.
14. The method according to claim 8 , which further comprises determining the stationarity of the noise component by virtue of temporal dynamics of the input signal being analyzed, namely by virtue of a maximum level and a minimum level of the input signal being ascertained and being compared with one another.
15. A hearing device, comprising:
a microphone;
a receiver; and
a signal processing unit connected to said microphone and said receiver, said signal processing unit configured to perform a method according to claim 1 .