| 摘要 |
PURPOSE:To reduce noise near a microphone by applying phase correction to an output signal from the microphone, supplying the result to an acoustic transducer so as to interfere noise near the microphone with a sound generated from the acoustic transducer. CONSTITUTION:The output signal of the microphone 1 arranged near the head of a person seated on a seat is subjected to phase correction and the result is supplied to the acoustic transducer 2 arranged near the microphone 1. Thus, the noise near the microphone 1 and the sound generated from the acoustic transducer 2 are interfered with each other to cancel noise. Thus, the noise near the microphone 1 is reduced. Moreover, the acoustic transducer 2 consists of a gas adsorbing body 4 and a temperature control means 5 controlling the temperature of the gas adsorbing body 4 and since the transducer 2 generates efficiently the sound of a low sound frequency especially regardless of small sized configuration, the noise at low sound frequency is decreased. |
