I'm using Audio Queue Framework with sample rate 44100 Hz to record data from the microphone on iPhone.
Then I test frequency response for iPhone 4 and iPhone 4s. iPhone 4s mic is blind on frequencies higher than 20 kHz unlike iPhone 4.
It seems like the microphone is better on previous model. Is it hardware limitation? Is it software limitation? Or some misconfiguration (enabled noise compession or something else)?