Microphone frequency response for the iPhone 4

Microphone frequency responses for the previous iPhone:

What these curves say is what my feedback for the iStethoscope app has been suggesting: the original iphone had a poor built-in mic, the 3G had a very impressive mic (look at the low frequencies), the 3GS had a worse mic (iPad similar), and the iPhone 4 is slightly better than the 3GS.

Perhaps the most surprising result is that the inline mic provided with the white earphones may be better than we thought. According to those charts it should be better than all of the built in mics! The problem may be with the earphones themselves - they can't play the low frequencies back properly, so you just can't hear what the mic records. So one option if you're using a device with a worse built-in microphone compared to the iPhone 3G is to use the inline mic from the white headphones to gather the sounds, then use better headphones to listen to what you just sampled. Of course if you're using an iPad you can plug a USB mic into the camera connection kit and have great quality sound that way. Reports suggest that you can't do the same with the iPhone, however.