| 摘要 |
The application relates to a hearing device, e.g. a hearing aid, comprising a) an input transducer for converting an input sound to an electric input signal representing sound, b) an output transducer for converting a processed electric output signal to an output sound, c) a signal processing unit operationally coupled to the input and output transducers and configured to apply a forward gain to the electric input signal or a signal originating therefrom, and d) a frequency shifting unit for de-correlating the processed electric output signal and the electric input signal. The input transducer, the signal processing unit, the frequency shifting unit, and the output transducer form part of a forward path of the hearing device. The hearing device further comprises e) a feedback cancellation system for reducing a risk of howl due to acoustic or mechanical feedback of an external feedback path from the output transducer to the input transducer. The feedback cancellation system comprises e1) a feedback estimation unit comprising e1.1) a first adaptive filter for providing an estimate of said external feedback path, and e2) a combination unit located in the forward path. The feedback estimation unit provides a resulting feedback estimate signal, which is combined with the electric input signal or a signal derived therefrom in the combination unit to provide a resulting feedback corrected signal. The application further relates to a method of operating a hearing device. The object of the present application is to improve feedback cancellation in hearing devices. The problem is solved in that the feedback estimation unit further comprises e1.2) a correction unit for influencing said estimate of the feedback path by diminishing a residual bias in said resulting estimate of the feedback path, said residual bias being (e.g. a result of the frequency shift) introduced by the frequency shifting unit. This has the advantage of improving feedback cancellation, in particular in an acoustic environment comprising tonal components. The invention may e.g. be used for the hearing aids, headsets, ear phones, active ear protection systems, handsfree telephone systems, mobile telephones, teleconferencing systems, public address systems, karaoke systems, classroom amplification systems, etc. |
