| 摘要 |
PROBLEM TO BE SOLVED: To provide a loudspeaker which can adjust a volume automatically according to the condition of a place where guidance broadcasting is provided, such as a station platform, and reduce leak of sound around neighbors. SOLUTION: In the loudspeaker including a sound source for generating a sound signal, a controller for adjusting a volume of the sound signal generated by the sound source, an amplifier for amplifying the sound signal output from the controller, and a narrow directivity speaker for converting the sound signal output from the amplifier to sound waves and emitting the sound waves in a specified direction with a high directivity, there is further provided a measuring section which measures conditions in a range where the sound waves are emitted by the narrow directivity speaker and outputs the result as a measurement signal, so that the controller performs volume adjustment for the sound signal generated by the sound source according to the measurement signal output from the measuring section. COPYRIGHT: (C)2009,JPO&INPIT
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