PROBLEM TO BE SOLVED: To provide an ambient noise estimation device, capable of estimating the level of ambient noise even when sound is output constantly without silence from a speaker.;SOLUTION: A band-rejection filter 16 restricts an output frequency bandwidth of a flat speaker 13. A level detection unit 17 detects a sound pressure level of a sound signal input, and outputs it to an ambient noise level estimation unit 18. The ambient noise level estimation unit 18 estimates the ambient noise level around an audio output device 1 on the basis of a sound signal in which an element of prescribed frequency bandwidth is restricted by the band-rejection filter 16. An adjustment unit 19 adjusts an amplification amount of an amplifier 15 according to the ambient noise level input from the ambient noise level estimation unit 18. For instance, the amplifier amount is increased or decreased depending on the increase or decrease of the sound volume, assuming the ambient noise level input at the initial installation of the audio output device 1 as a reference sound volume.;COPYRIGHT: (C)2014,JPO&INPIT
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