Speech signal transmission system e.g. for motor vehicle hands-free telephone, adjusts filter so that difference signal is minimum for given harmonic frequency

摘要

A sensor detects the fundamental frequency of a discrete noise signal spectrum. The sensor is connected to at least one control circuit comprising a reference signal source, an adjustable filter and a subtraction circuit which subtracts the filtered reference signal from the speech signal produced by an electroacoustic transducer. The filter is adjusted so that the difference signal is minimized for a certain harmonic frequency. An Independent claim is included for a method of speech signal transmission for vehicles.