If you’re recording sound through your computer’s sound port, you can adjust the input volume to compensate for the sound source being too loud or quiet.
For example, if you’re recording loud music, lower the input volume so the recorded sound isn’t too loud or distorted. Or if you are recording someone who is speaking softly, increase the input volume so your Mac can better capture the person’s voice.
To capture less background noise when using your computer’s built-in microphone, select “Use ambient noise reduction.”
Note: You can’t adjust the input volume for a digital input device using your computer’s controls. You must adjust the input volume from its source, such as a receiver.