Adaptive long-term prediction filter for adaptive whitening

摘要

The invention relates to a hearing instrument for processing an input sound to an output sound according to a user's needs. The invention further relates to a method of estimating acoustic feedback in a hearing instrument. The object of the present invention is to reduce the impact of tonal components in the target input signal on the quality of the estimate of acoustic feedback. The problem is solved in that hearing instrument comprises an input transducer for converting an input sound to an electric input signal and an output transducer for converting a processed electric output signal to an output sound, a forward path being defined between the input transducer and the output transducer and comprising a signal processing unit defining an input side and an output side of the forward path, a feedback loop from the output side to the input side comprising a feedback cancellation system for estimating the effect of acoustic feedback from the output transducer to the input transducer, the feedback cancellation system comprising a feedback path estimation unit receiving first and second estimation input signals from the input and output side of the forward path, respectively, wherein the first and second estimation input signal paths comprise first and second long term prediction filters P(z) each having an input and an output, the feedback cancellation system being adapted to provide that the variable parameters of at least one of the long term prediction filters are estimated based on the input signal to the filter in question. Embodiments of the invention have the advantage of leading to better feedback cancellation, even for tonal input signals. The invention may e.g. be used for the hearing instruments or headsets.