AUDIO HELMET WITH ACTIVE NON-ADAPTIVE TYPE NOISE CONTROL FOR LISTENING TO AUDIO MUSIC SOURCE AND / OR HANDS-FREE TELEPHONE FUNCTIONS

摘要

The helmet comprises two earphones each having a sound reproduction transducer (18) of an audio signal, housed in an acoustic cavity delimited by a shell provided with a circumaural pad. The active noise control includes, in parallel, a feedforward bandpass filter (32) receiving the signal from an external microphone (28), a feedback bandpass filter (42) receiving as input an error signal (e) ) delivered by an internal microphone (36), and a stabilizing bandpass filter (44) locally increasing the phase of the transfer function of the feedback filter in an instability zone, especially a waterbed effect area around 1 kHz . An adder (46) provides a weighted linear combination of the signals delivered by these filters as well as the audio signal to be reproduced (S). The control is non-adaptive, the parameters of the filters (32, 42, 44) being fixed.