| 摘要 |
PURPOSE:To prevent generation of echo and singing without interference in normal conversation by using only the half of a sound spectrum band. CONSTITUTION:Receiving sound signal a from receiver or two wire-four wire converter 6 has the sound spectrum band divided into narrow bands at, for example, an interval of 100Hz by receiving circuit 7, and only even-numbered narrow band spectrums are supplied to speaker 1. Meanwhile, voice of a talking person is converted to signal c by microphone 2, and only odd-numbered narrow band spectrums are supplied to transmitter or converter 6 by transmission circuit 8 having a characteristic complementary for receiving circuit 7. Consequently, sound radiated from speaker 1 is prevented from being transmitted to the transmission system through microphone 2 and circuit 8, so that complete simultaneous services can be performed. |
