他通过调音台调节声音的音调，使其更加柔和。

He ___modulates the pitch of the sound through the mixer to make it softer.

智能音响会根据周围噪音自动调节音量。

The smart speaker automatically ___modulates the volume based on ambient noise.

智能手机通过调制无线电信号来发送信息。

Smartphones ___modulate radio signals to send messages.