Sound issues???

[CoryBantic]

I recently went to a concert and took some video of a performance with my Evo. My cousin went with me and he recorded some video with his Iphone 4. The next day we e-mailed each other the videos and the sound from my vid was very distorted while his was very clear. Could it be that I have a bad microphone? Or is his phone's just better? Is there a way to adjust the incoming volume on the Evo or maybe an app?