| 摘要 |
PURPOSE:To save the number of echo cancellors by providing an echo cancellor in an exchange so as to use the echo canceller in common. CONSTITUTION:The exchange connecting lines between plural telephone sets including a loudspeaker telephone set is provided with the echo canceller, a loudspeaker talking detection circuit 608 and a control circuit 606. The circuit 606 detects whether or not a telephone set in line connecting state conducts loudspeaker talking and the circuit 606 inserts the echo canceller to the line at the loudspeaker talking depending on the output of the circuit 608 and controls the system so as to eliminate the acoustic coupling between the speaker and microphone of the loudspeaker telephone set 609. Thus the echo canceller is used in common and the required number is saved. |
