| 摘要 |
An audio interface couples a telephone handset to a computer over a Universal Serial Bus and detects/attenuates echo return loss in the voice signals going through the interface. The computer is coupled to a packet switched network, such as the Internet or some other WAN. The audio interface includes a codec for generating 8-bit mu-law signals from analog voice signals and vice versa. A microprocessor converts the mu-law signals to 16-bit linear signals and monitors these signals for signs of speech. If receive speech is detected, the transmit path is attenuated. If transmit speech is detected, the receive path is attenuated. If both transmit and receive speech is detected, the receive path is partially attenuated.
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