| 摘要 |
PURPOSE:To adjust automatically the sound volume of a speaker according to a peripheral noise level by adjusting the sound volume of sound signals by the subtraction output if the output-side sound signal of a sound volume adjustment equipment has a value larger than the larger voltage value of two comparators and stopping the adjustment function otherwise. CONSTITUTION:Level comparators 13 and 14 compare the level of signals which are converted from output-side sound signals of sound volume adjustment epuipment 3. If the level of signals which are converted from output-side sound signals of sound volume adjustment equipment 3 is larger than the larger one of respective comparison voltage of comparators 13 and 14, the subtraction output is stored and held, and the storage holding function is released repeatedly for a fixed time at a fixed period to adjust the sound volume of sound signals by the subtraction output. Meanwhile, if the level of signals which are converted from output-side sound signals of adjustment equipment 3 is smaller than the smaller one of respective comparison voltages of comparators 13 and 14, the subtraction output is set to zero to stop the adjustment function of adjustment equipment 3. As a result, the sound volume of a speaker can be adjusted automatically according to the peripheral noise level. |
