iPhone 7 - muffled top speaker + others complaining of my calls fading in/out

[NewBench]

I recently bought a used iPhone 7 (32GB, matte black).

When making or receiving a phone call, I experience the following issues:

• 'Muffled' audio from the top speaker, sounds like someone is talking through a radio, there is static/white noise when someone talks (I can still hear their voice and understand them, but it's accompanied by static/white noise when they talk).
• People on the other end of the call complaining about me sounding 'quiet' when I'm talking at a normal volume
• People on the other end of the call complaining about the sound fading in and out, sometimes almost completely silent according to them.

I tried recording a voice memo and playing it back through the top speaker and it sounded 'okay'. The bottom speaker is working fine.

Signal bars are always full, my network (O2 - UK) shows good 4G coverage inside and outside and not had this before with other iPhones. Tried making a call in another part of town with good network coverage and same issues.

The top speaker bar/grill looks clean, I've tried blowing air into it with no improvement.

Any suggestions?

Thanks

 

[C DM]

Perhaps there was some (liquid) damage at some point?

 

[NewBench]

Returned it, bought a different handset instead. Problem solved.

 

[Lekro]

FYI don’t blow air into speaker and microphone grills. It can kill the membrane.

The issue was probably audio IC with that 7. It was a good call to get a new phone.