How is squelch adjusted so that a weak FM signal can be heard?

The squelch circuit mutes the receiver's audio when no signal is present, saving you from having to listen to constant background static. To hear a very weak FM signal that isn't strong enough to automatically 'break' the squelch, you must manually lower the squelch threshold until the background noise is heard continuously. Opening the squelch fully ensures that the audio path remains active, allowing any faint, incoming signal to pass through the speaker along with the static. Turning up the audio volume will not open the squelch gate, and standard radios do not feature 'anti-squelch' or 'squelch enhancement' functions.