| 摘要 |
PROBLEM TO BE SOLVED: To reduce the abnormal sound by resonance caused by walls, furniture, lighting machines in a listening room without causing quality deterioration on audibility. SOLUTION: A volume value is set at an initial value (S101), a pure tone signal of a predetermined frequency is output as a test signal from a speaker (S102), and an output test signal is picked up by a microphone (S103). When the signal level of harmonic component of a pickup signal is a threshold or higher, the volume value is reduced until the signal level becomes under the threshold (S106), and the volume value after the reduction is stored (S110). When an acoustic signal is output, the signal level of the frequency of the acoustic signal is adjusted so that the product of the signal level at the stored frequency and the present volume value does not exceed the product of the signal level of the test signal and the stored volume value. COPYRIGHT: (C)2011,JPO&INPIT
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