| 摘要 |
PURPOSE:To set the optimal sound volume corresponding to the external environment by controlling automatically the sound volume generated by an acoustic device in accordance with a tendency of a variation of a noise of the external environment. CONSTITUTION:An electric signal inputted from a sound generating part 11 is outputted through an amplifying part 26 for executing an amplification processing by obtained gain (g). This gain (g) is changed automatically in accordance with a variation of a noise level of the outside of an acoustic device by setting a sound volume level set by a user's volume operation as an initial value. In such a state, when a code of an average variation G at the time when it is varied in the direction in which a noise level becomes high is positive, the gain (g) set to the amplifying part 26 is increased by taking the sum to the initialized gain G by a gain calculating part 22. Accordingly, as the noise level becomes high, the sound volume becomes large. On the other hand, in the case the noise level is varied in the direction in which it becomes low, the average variation G becomes negative, the sum to the gain G is taken by the calculating part 22, and (g) of the amplifying part 26 becomes small. |
