| 摘要 |
A speech transmitter having a tandem pass through function in an STM, ATM, and IP network. A noise canceller (21) is provided at the succeeding stage of an echo canceller (12) in an encoding section. If not a tandem connection state, noise is removed to carry out high-efficiency encoding; if the relay is in a tandem connection state, switching is carried out so that the operation of the noise canceller (21) is stopped so as to prevent degradation of speech quality due to excessive decoding and encoding. As a result, even if a portable telephone has no noise canceling function, high-quality speech transmission is realized in both normal and tandem pass through modes. By thus removing the noise component, the soundless portions in speech data increase, and the portions to be encoded decrease, thereby reducing the amount of data transmitted through the circuit. |
