| 摘要 |
PROBLEM TO BE SOLVED: To provide broadcast easy to listen by avoiding noises when guidance broadcast should be carried out with a microphone and the like under intensively noisy environment. SOLUTION: A sound collecting means (4 or 13) is provided under noisy environment, and an equalizer (10) is inserted between the sound collecting means and an amplifying means (AMP) for receiving and amplifying an output signal of the sound collecting means. The equalizer is so pre-set that at least two patterns X (not shown) of a frequency factor and a gain to the frequency factor within an audible range from 2,000 Hz to 4,000 Hz can be changed. In this case, a control signal for turning on/off the pre-set equalizer intermittently in response to whether a noise sensor (1) senses prescribed sound pressure or not is fed to the equalizer. COPYRIGHT: (C)2006,JPO&NCIPI
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