When I got my iPhone 4 I noticed that only the right speaker worked.
I got worried and even considered bringing the phone to an Apple Store to get it checked out, but soon I found a solution.
Well, the thing is, iPhones always had one speaker only!
That's right. If you also were worried about your left speaker wasn't working, just sit down and relax because the left one is not a speaker but yes a microphone.
Check the picture below with all iPhone 4 parts labeled.
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