Noise reducing sound reproduction system

摘要

A noise reducing sound reproduction system and method may be operable with an input signal supplied to a loudspeaker by which it is acoustically radiated. The signal radiated by the loudspeaker may be received by a microphone that is acoustically coupled to the loudspeaker via a secondary path and that provides a microphone output signal. From the microphone output signal a useful-signal can be subtracted to generate a filter input signal. The filter input signal is filtered in an active noise reduction filter to generate an error signal, and the useful-signal is subtracted from the error signal to generate the loudspeaker input signal. In addition, the useful-signal is filtered by one or more spectrum shaping filters prior to subtraction from the microphone output signal or the loudspeaker input signal or both.

主权项

1. A noise reducing sound reproduction system comprising:
a loudspeaker that is connected to a loudspeaker input path; a microphone that is acoustically coupled to the loudspeaker via a secondary path and connected to a first end of a microphone output path, the secondary path having a secondary path transfer characteristic; a first subtractor that is connected to a second end of the microphone output path and a first end of a first useful-signal path; an active noise reduction filter that is connected downstream of the first subtractor; and a second subtractor that is connected between the active noise reduction filter and the loudspeaker input path, the second subtractor further connected to a first end of a second useful-signal path; wherein
a second end of the first useful-signal path and a second end of the second useful-signal path are connected with each other and configured to receive a useful signal to be reproduced by the loudspeaker, the useful signal being a signal before subtraction at the first or second subtractor,at least one of the first useful-signal path or the second useful-signal path comprises one or more spectrum shaping filters, at least one of the one or more spectrum shaping filters having a transfer characteristic that models the secondary path transfer characteristic, anda filter input signal is supplied to the active noise reduction filter by the first subtractor, the filter input signal approaching zero when noise reduction of the noise reduction filter is active.