| 摘要 |
PURPOSE:To effectively and easily execute the removal of an echo in a hall by adding the output of a serial connection circuit with an input signal and inputting the addition output to a speaker. CONSTITUTION:Sound signals to be regenerated by speakers 2, 3 are respectively inputted to input terminals 10, 11. The signal is converted at an A/D converter 12, 13 from an analog signal to a digital signal of about 8 bits, then inputted to addition points 14, 15, outputted there, converted inversely to the analog signal by D/A converters 16, 17, and inputted from output terminals 18, 19 to speakers 2, 3. The delay time of delay circuits 20, 21 are adjusted to a time added with time to reverse that signal, the attenuation quantity of a gain setting circuit 22, 23 is adjusted so that the output sound wave goes to the level of echoes A', B' at an audience seat 4, and equalizers 24, 25 are operated as an LPF of cut-off frequency 4kHz, for example. This output component is an inverted sound wave of a phase at the same level as the echoes A', B', so the echoes A', B' are cancelled by the sound wave for cancelling from the speaker. |
