Why is the volume on my iphone 4s so low?

Question

On calls i can barely hear people but music and siri is loud and just fine..the volume is turned all the way up for calls so what could be the problem?

Answer 1

I replaced my iPhone4 with another one and it was no better.  Later I replaced it with an iPhone5.  It was much improved. Why ?  I am not really sure, but when I got the iPhone5 either the speaker is better or the Plastic Cover is a little different.  I think the openings on my 5's plastic protector are larger and I made sure the plastic does not even come close to the earpiece.  My wife did not want my 4 because she could not hear well on it; so, I bought her a 5 also.  She likes the 5 and says she can hear better.   Improved earpiece ? - perhaps.  Plastic Screen protector not covering the earpiece - I am sure it is not, but it was not on the 4 either.  I think if you drop a phone it might jar the earpiece, but I have never taken one apart.  The Apple Store should know, but I took my 4 there and they only listened to it and said it was ok, but it was not.
I think the earpieces are marginal and the circuitry are marginal prior to a 5 or perhaps the earpieces were not all manfactured by the same vendor.  Either way you look at it, if you have a problem hearing on a $600 phone, take it back until you get a good one.