| 摘要 |
PURPOSE:To convert a training signal, which is rasping and damages an acoustic system, to a mimic chord signal by providing a filter, which converts the training signal to the mimic chord signal, and a reverse filter having the opposite transmission characteristic before and after an echo path. CONSTITUTION:The inputted training signal is expressed with a function d'n. Consequently, a formula I indicates that the performance of an echo canceller 10 is not affected by insertion of two filters 1 and 2, which has transmission characteristics opposite to each other, between the canceller 10 and an echo path 3 of impulse response Ri. If a digital filter using the PARCOR system is used as the filter 1, the rasping training signal is converted to melody. It is converted back to the training signal again by the reverse filter 2 through the echo path 3; and thus, melody is heard from a speaker or an earphone during the training period.
|
