To way the sound of.

改变(音调)。

To tone down.

缓和；减轻。

To impress upon (a carrier wave) the low-frequency pattern of sound waves or other signals by varying the amplitude, frequency, or phase of the carrier wave.

【电】调节频率(改变载波之振幅、周波或周率以加强低频率之音波)。

To pass from one key to a related key.

【乐】转调。