초록 ▼

In order to reduce the noise signal of an acoustic origin contained in an input signal coming from a microphone located in a noisy environment, a noise reducing arrangement includes a filter (6) which receives the input signal and eliminates a frequency band of some hundreds of Hertz, centered aroun

In order to reduce the noise signal of an acoustic origin contained in an input signal coming from a microphone located in a noisy environment, a noise reducing arrangement includes a filter (6) which receives the input signal and eliminates a frequency band of some hundreds of Hertz, centered around the average frequency of the first formant of the speech signal, a detector circuit (7) detecting the output signal of the filter (6) with a time constant to the order of some tenths of a second, finally a variable-threshold circuit (9) which uses the detected signal as the threshold signal and which is arranged for transmitting the variations of the input signal when the latter has an absolute value which is higher than the threshold signal.

대표청구항 ▼

An arrangement for reducing the noise in an input signal formed by a speech signal mixed with noise, characterized in that the arrangement comprises a band-stop filter which receives the input signal and eliminates a frequency band which is approximately centered around the average frequency of the

An arrangement for reducing the noise in an input signal formed by a speech signal mixed with noise, characterized in that the arrangement comprises a band-stop filter which receives the input signal and eliminates a frequency band which is approximately centered around the average frequency of the first formant of the speech signal and which covers at least a portion of the frequency band of the first format, a detection circuit for detecting the level of the output signal of the band-stop filter, said detection circuit having a long time constant to the order of the time constant of the variation of the average noise level, and a variable-threshold circuit to which a threshold signal is applied, said threshold signal being formed from the detected signal and which is arranged for transmitting the variation of the input signal when the absolute value of said input signal is higher than the threshold level.