Patent ID: 7711124

Claim:
A method for attenuating the low frequency noise generated at the outlet ( 18 ) of an exhaust line ( 14 ), wherein it comprises the steps of: defining a signal (Δf b ) representing the noise to be attenuated, emitting a first high-frequency sound wave (F 1 ) from a first transducer ( 22 ) into an attenuation zone ( 26 ) of the exhaust line ( 14 ), which first high-frequency sound wave (F 1 ) is inaudible and has a carrier frequency of higher than 50 kHz, and emitting a second high-frequency sound wave (F 1 +Δf cb ) from a second transducer ( 24 ) into the attenuation zone ( 26 ) of the exhaust line, the first and second transducers ( 22 , 24 ) being configured for generating interference between the first and second sound waves in the attenuation zone ( 26 ), which second sound wave is inaudible and has as its carrier frequency the carrier frequency of the first high-frequency sound wave (F 1 ) and contains a low-frequency counter-noise signal (Δf cb ), which is in opposition of phase to the signal (Δf b ) representing the noise to be attenuated.