A Galaxy S21+ whose microphone is faint or silent has three microphones to consider: one on the bottom edge, one at the top and one next to the rear cameras. A case that covers the bottom edge, pocket lint in the openings or a thick film can muffle the main call microphone, and removing the case and brushing the openings is the quickest test. Record a voice memo to test the bottom microphone, a video to test the rear one and a call at the ear to test the top:
The checks in more detail
if only one is weak, you know which opening or part is the problem. The Samsung Members app has a microphone diagnostic. Turn off Bluetooth in case the call has moved to a headset, and check the call's noise reduction setting, which can clip a quiet voice. App permissions under Settings, Apps, the app, Permissions, Microphone matter for a single app. Restart and wipe the cache partition after a major update. A recording that is silent in every app after these steps needs a repair.
The S21+ is old enough that dust in the openings is common. Pocket lint in the bottom opening is the commonest cause on an S21+ that has lived in a jeans pocket for years, and a wooden toothpick or a soft brush cleans it, but never use a pin. If cleaning helps for a few weeks and the sound returns to muffled, lint is returning and a case with a bottom cover may help. If you use voice assistants, Bixby or Google Assistant use the same microphone, so test wake words in a quiet room;
a phone that hears you for Assistant but not for calls has a call-path problem and not a microphone fault. Update the Phone app through Galaxy Store, since call quality fixes arrive that way. Samsung Members' error reporting can collect logs of audio problems and share them with Samsung, which is useful when the fault is intermittent: if the microphone fails only now and then, enable the error report, reproduce the fault and send it. An intermittent fault is often a loose connection that a repair desk can find from the logs.
Differential
Likely causes of “Samsung Galaxy S21+ microphone is quiet, muffled or not working”, and how to tell them apart
- 1
A case or lint over the bottom edge
What separates it Voice is faint
How to confirm Remove the case and brush the openings
- 2
Bluetooth taking the call
What separates it The other person hears nothing
How to confirm Turn Bluetooth off
- 3
Noise reduction clipping
What separates it Quiet voices are cut
How to confirm Turn off noise reduction in call settings
- 4
A permission off
What separates it One app cannot use the mic
How to confirm Allow it in Permissions
- 5
A hardware fault
What separates it The recording is silent
How to confirm Contact Samsung
Before you touch a setting
Record this first — changing settings destroys the evidence
- Which of the three tests is weak
- Whether Bluetooth is connected
- The diagnostic result
- The case
Try in this order
0 of 8 completedTest the three microphones
ReversibleRecord a memo, a video and a call at the ear.
Remove the case
ReversibleAnd brush the openings.
Turn off Bluetooth
ReversibleTo test a call.
Check noise reduction
ReversibleIn call settings.
Run the diagnostic
ReversibleIn Samsung Members.
Wipe the cache partition
ReversibleAfter an update.
Clean the bottom opening
ReversibleWith a soft brush.
Choose a case with a bottom opening
ReversibleTo keep lint out.
Model-specific
What is true of this model and not of its siblings
- Three microphones
- Bottom, top and rear.
- Age
- Lint builds up over years.
- Pocket lint
- The commonest cause.
- Cases
- A good case limits lint.
Stop boundary
When this stops being a self-service repair
- !If a recording is silent in every app, contact Samsung
- !If only one microphone is weak, tell the repair desk
- !Water exposure needs service
Evidence ledger
Sources behind this answer
Exact questions
Common questions
Why can't people hear me on my S21+?+
A blocked opening, Bluetooth or a setting.
How many microphones does it have?+
Three.
How do I test them?+
With a memo, a video and a call.
Does lint matter?+
Yes.
How often should I clean?+
When sound is muffled.
Can I use a pin?+
No.