| 摘要 |
A hands-free telephone set which is connected to both an analog cellular scheme line and a digital cellular scheme line includes first and second FIR filters. The first FIR filter is connected to a transmission path in an analog line connection state to cancel an acoustic echo generated when reception speech leaks to the transmission path. The second FIR filter is connected to a reception path in the analog line connection state, disconnected from the reception path, and cascaded to the first FIR filter in a digital line connection state. The second FIR filter constitutes a line echo canceler for canceling a line echo generated when transmission speech leaks to the reception path. In the digital line connection state, the cascaded first and second FIR filters constitute an acoustic echo canceler for canceling an acoustic echo generated when reception speech leaks to the transmission path.
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