MacBook Pro: diagnosing sound and microphone issues
Silent speakers, a mic that picks up poorly, a headphone jack that stops reacting: the checking method before suspecting a hardware failure.
Speakers and headphone jack
Missing or distorted sound affecting only internal or only external devices often comes from liquid damage or debris in the headphone jack. Remove any connected headphones or external speaker, gently clean the jack with a small, soft, non-metallic brush, then check in Sound settings that internal speakers are selected with an appropriate volume.
Microphone
A mic that picks up nothing, distorted audio, or an internal microphone missing from the device list share similar causes: liquid damage, or headphones plugged in blocking internal mic selection. Unplug any headphones, clean the jack, then check that the internal microphone is selected with a non-zero input level — the level indicator should react when you speak.
Beyond the basic checks
If the problem persists, Apple's diagnostic suites let you go further before considering replacing the audio board, the speakers, the top case (which houses the microphone), or the logic board.
