Symptoms
- Constant hissing or white-noise sound layered under the call
- Hiss is present even in quiet rooms
- Other person also hears the hiss
- Hiss disappears when switching to speakerphone or a different mic
Likely causes
- CommonWeak cellular signal introducing line noiseMarginal signal areas often add a persistent hiss or static-like noise to calls.
- CommonBluetooth device with a noisy or failing connectionSome Bluetooth accessories introduce a hiss when the connection is weak or the device is aging.
- PossibleBackground noise suppression malfunctioningThe phone's software noise reduction can occasionally introduce artifacts instead of removing noise.
- PossibleEnvironmental noise being picked up by the micFans, AC units, or wind can create a hiss-like sound that the mic picks up.
- Less commonMicrophone hardware issueA failing mic component can produce a constant hiss regardless of environment.
What to do
- Move to an area with better cellular signal and see if the hiss reduces.
- Disconnect Bluetooth and use the phone's built-in mic and speaker to compare.
- Move away from fans, air conditioning units, or open windows that could be adding background noise.
- Restart the phone to reset any stuck noise-processing software.
- Ask the other caller if the hiss is coming from your end or theirs.
- Update your phone's software in case a noise suppression bug has been fixed.
- Test the mic with a voice memo recording in a silent room to check for hiss outside of calls.
- If hiss is present in every recording and call regardless of environment, have the microphone checked professionally.
When to call a pro
If a constant hiss appears in every recording and call regardless of signal or environment, have the microphone hardware tested.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.