The short answer
Phones have two or three microphones for calls, noise cancellation and video. Test each one with a voice recorder, the camera and a speakerphone call, because the results tell you which is blocked. Lint in the bottom microphone port and a case covering it are the two most common causes.
A modern phone uses several microphones together: one at the bottom for your voice, one at the top for noise cancellation, and often one near the camera for video. Noise cancellation works by comparing what the microphones hear and subtracting the difference, which means a blocked microphone does not simply reduce volume, it can actively remove your voice.
Test each microphone
Record with the voice recorder app
This uses the bottom microphone. Speak normally, then play it back. Quiet or muffled means that microphone is blocked.
Record a video
This uses the top or rear microphone. Compare the clarity against the voice recorder.
Make a call on speakerphone
This often uses a different microphone configuration. If people can hear you on speaker but not otherwise, the bottom microphone is the problem.
Try a call with headphones
If you are clear through headphones, the phone’s own microphones are the issue rather than the network or the app.
Cover each microphone in turn while recording
This confirms which opening corresponds to which microphone on your model, and whether one is already effectively covered.
Cause 1: something is blocking it
- Pocket lint in the bottom port, which sits beside the charging connector and collects the same debris. This is the most common cause by a wide margin.
- A case covering a microphone opening, particularly a case fitted slightly off or one made for a similar but different model.
- A screen protector covering the top microphone, which sits near the earpiece.
- A film left on a new phone over the microphone opening.
Clean carefully with a dry soft brush, pointing the phone downwards so debris falls out. Do not push anything into the opening, and do not use liquid or compressed air, both of which can damage the microphone membrane.
Microphone membranes are delicate. A pin or a needle pushed into the port will destroy it, and this is a frequent cause of turning a cleanable blockage into a repair. Brush from the outside only.
Cause 2: noise cancellation working against you
If one microphone is blocked, the noise cancellation algorithm may interpret your voice as noise and remove it. The result is people hearing background sound clearly and your voice barely at all, which is a distinctive symptom.
Some phones allow noise cancellation to be disabled in call settings or accessibility options. Turning it off as a test is worthwhile, and if your voice returns, the underlying problem is still a blocked microphone that needs cleaning.
Cause 3: software and permissions
- Microphone permission for the calling or messaging app, which can be revoked by an update or by an unused-app cleanup.
- Another app holding the microphone, such as a recorder or an assistant left running. Close everything and retry.
- A Bluetooth device connected, which routes the microphone to earbuds in your pocket or a car in the driveway. This is extremely common and produces exactly this complaint.
- Restart the phone, which clears a stuck audio routing state.
- Safe mode on Android to rule out a third-party app interfering.
- A system update, since audio routing regressions do occur and are usually fixed quickly.
The Bluetooth one deserves emphasis: if earbuds are connected and in a drawer, the phone is faithfully transmitting the inside of the drawer. Check the Bluetooth status before anything else.
Cause 4: the network
If your voice is intermittent rather than absent, and the problem happens only in certain places, it is the connection rather than the microphone. Weak signal causes dropouts that the other person hears as your voice cutting out.
Wi-Fi calling can help, and on a poor Wi-Fi connection it makes things worse. Test on mobile data with a good signal to separate the two.
Cause 5: water damage
Water in a microphone port produces muffled or absent audio, and it often improves as the phone dries. Leave it somewhere warm and dry for a day. If the phone has been in salt water, rinse with fresh water first, since salt residue continues to corrode after the water has gone.
Before booking a repair, check whether the manufacturer’s support app includes a microphone test. Most do, and running it gives you a definitive result to take to the repair shop rather than a description of the symptom.
When it is hardware
If one microphone tests as dead across every app, with the port clean, no case, no Bluetooth device connected and after a restart, the microphone or its connector has failed. On most phones the bottom microphone is part of the charging port assembly, which is a modular and relatively inexpensive repair. That is worth knowing, because it is one of the cheaper faults to fix.
Why can people hear me on speakerphone but not normally?
Different microphones are used. Working on speaker and failing otherwise points at the bottom microphone being blocked or failed, which is the one beside the charging port.
Can a case block the microphone?
Easily, particularly a case made for a similar model or fitted slightly off. Removing the case and testing takes ten seconds and resolves a surprising number of cases.
Why does my voice sound like it is cutting out?
That is usually connection quality rather than the microphone. Test in a place with a strong signal and on a different network to confirm.
How do I clean a phone microphone safely?
A dry soft brush from the outside, with the phone pointing downwards. Never insert anything into the opening, and never use liquid or compressed air.
Is a microphone repair expensive?
On most phones the bottom microphone is part of the charging port module, which is one of the cheaper modular repairs. Get a quote rather than assuming the phone needs replacing.
The order
Check Bluetooth is not routing your voice to earbuds in a drawer. Take the case off and test each microphone with the recorder, the camera and a speakerphone call. Brush the bottom port dry. Check app permissions and restart. Test on a strong signal to rule out the network. Then run the manufacturer’s microphone test before booking anything.
