HTC One X - recording filters high frequencies I've got an HTC One X, on which I'm trying to record uncompressed WAV audio. 

In particular, I'm interested in a 13.5 kHz sound. Other Android devices pick up that frequency easily, and so do iOS devices, but the HTC One X doesn't.

For example, the spectrogram below shows the same recording from the HTC One X (top) and an HTC One V (bottom), recorded with the same app (called Hertz, but any will do), with identical settings (mainly 44,100 Hz sampling rate).

Why is the One X not picking up the same?


Is the microphone different?
Is there any low-pass filter applied that I'm not aware of? If so, how can remove it?


Trying with different apps (e.g. Audalyzer) doesn't make any difference.
It doesn't say it on HTC's website under the specs for the One X, but this review points out that the phone has dual-microphones, used for sound cancellation during phone calls. My guess is perhaps your recording app is recording from the wrong microphone? Or using both to cancel out the pitch you're looking for?

I'd look for settings in your recording apps about using the dual-microphones. I don't have a phone with two, so I can't test that for you :/

Good luck though!