echo(ed) signal

例句：

1. 1. The sound of the waves echoed through the valley.
   海浪的声音在山谷中回荡。
2. 2. The music echoed throughout the hall.
   音乐在整个大厅里回荡。
3. 3. The echoes of history are still felt in many places today.
   历史的声音仍然在许多地方感受到。