iPhone's outbound is too low

[Flaki]

My mother has iPhone and everyone says that her voice is really low.

Is there any way to increase the outbound? Or is the build in mic in the stock earphone that comes with iPhone bad?

 

[Gadgetgeezer]

There might be dirt dust on the mic grill (right hand grill at bottom of phone). Or the mic might need changing out - a soldering job unless you change the mic/speaker/dock as a unit.