Method for compensating for a feedback signal, and hearing device
Feedback in a hearing device and, more particularly, in a hearing aid should be compensated for before it becomes audible. To this end, a method is proposed for compensating for a feedback signal in a hearing device with an input-transducer apparatus, a signal-processing apparatus and an output-transducer apparatus, in which method a feedback signal is compensated for, which feedback signal is fed back to the input-transducer apparatus from the output-transducer apparatus or the signal-processing apparatus. More particularly, a probability of having a plurality of notches, equally spaced apart from one another, in the spectrum of an input signal is established, which input signal originates directly from the input-transducer apparatus or which is a difference signal between the signal directly from the input-transducer apparatus and a compensation signal serving for compensation. The compensation is modified or the signal-processing apparatus is amplified as a function of this established probability.
1. A method for compensating for a feedback signal in a hearing device having an input-transducer apparatus, a signal-processing apparatus and an output-transducer apparatus, which comprises the steps of:
compensating for the feedback signal being fed back to the input-transducer apparatus from the output-transducer apparatus or the signal-processing apparatus;
establishing a probability of having a plurality of notches, equally spaced apart from one another, in a spectrum of an input signal, which originates directly from the input-transducer apparatus or which is a difference signal between a signal directly from the input-transducer apparatus and a compensation signal serving for compensation; and
modifying a compensation or an amplification of the signal-processing apparatus in dependence on the probability established.
2. The method according to claim 1 , which comprises establishing the probability in a speech phase during an intended operation of the hearing device.
3. The method according to claim 1 , wherein a transfer function from the input signal to the output signal corresponds to a comb filter.
4. The method according to claim 1 , which further comprises establishing the probability in a noisy frequency range of the input signal.
5. The method according to claim 1 , which further comprises verifying the feedback signal by virtue of the fact that an output signal is phase modulated and the notches are analyzed in respect of phase modulation.
6. The method according to claim 1 , which further comprises bringing about compensation via an adaptive filter and modifying an adaptation speed in dependence on the probability.
7. The method according to claim 6 , which further comprises modifying the compensation to the effect that a transfer function of a compensated signal, created by mixing the input signal with the compensation signal for compensating for the feedback signal, to the output signal is substantially without a gradient in a greatest part of a prescribed spectral range, which should be influenced by the compensation.
8. The method according to claim 1 , wherein the notches, equally spaced apart from one another, in the input signal after the input-transducer apparatus are directly compared to same spaced-apart notches in a compensated signal for validating a detection of a feedback situation.
9. A hearing device, comprising:
an input-transducer apparatus;
a signal-processing apparatus for processing an input signal emitted by said input-transducer apparatus to form an output signal;
an output-transducer apparatus for converting the output signal into an acoustic output signal;
a compensation apparatus for compensating for a feedback signal, being fed back to said input-transducer apparatus from said output-transducer apparatus or said signal-processing apparatus;
a detection apparatus for establishing a probability of a spectrum of the input signal having a plurality of notches, equally spaced apart from one another; and
said compensation apparatus being controlled in dependence on the probability established.