I have a project in which I am considering using the microphone from a smartphone for the reception of inaudible signals (> 15khz).
What is the frequency range that such a microphone of receive sound? And what is the maximum frequency ?
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The best idea is to ignore what everyone says, and test it yourself. Install an app like "SpectralPro Analyzer", and either generate some high frequency sounds using PC programming (easy) or download some high-frequency MP3's from web sites.
I've done all of the above on many different phones - I find that I get excellent results for a very long way off the top of my hearing range, at least as high as 21kHz (the limit for those apps). The interesting thing about this is:
a) everyone who said PC speakers can't do 21kHz was wrong, and
b) everyone who said smartphone microphones can't pick up high frequencies was wrong too.
Bottom line - almost everyone who's never tried this stuff makes a guess. Good intentions don't make their guessing relevant though :-(
Best of luck with your project!
Here's a Samsung Galaxy Note-1 recording a Macbook Pro signal which went from 9kHz to 21kHz:
This is likely to be different for each manufacturer / model and something you'll either need to test yourself or do some searching of manufacturer specifications and/or tests that other have performed. For example here's an iPhone microphone frequency response comparison:
Also note that many people, especially the young, can hear up to 20 kHz and sometimes beyond so what you're trying to achieve probably won't be possible on most phones.
Apparently it is possible for a smartphone microphone to pick up on sounds that most people can't hear, because:
It depends entirely on the phone, they will all use different microphones/circuits.
Generally, an audio mic will be within a range of 20Hz - 20kHz. Many cheaper mics ( or intended for voice only) will have a lower cutoff frequency of 15kHz or less. The circuit the mic is attached to may intentionally roll off the frequency - various DSP techniques are used to minimise background noise and feedback, adjust compression, etc - so the software processing is quite sophisticated and dynamic on a modern mobile phone.
At a guess, you should be able to rely on at least 100Hz - 10kHz.
For a particular model, have a look at the specs, it should give at least some basic detail on the microphone input range. Or do some testing with a function generator and some recording app on the phone.
As a first time iPhone user (and trained BBC recordist) I am beyond impressed by the audio. Spectrum analyser app (Octave RTA) registers down to 16 Hz and up to 20 kHz on my iPhone 7. Live concert organ is very well recorded, pedals and all, albeit mono. The 19kHz pilot tone leakage from an FM radio speaker is perfectly visible.
I have no way to confirm flatness of response, though a natural white noise source such as a waterfall is displayed without evident peaks or banding. Recording speeach alongside a good studio condenser mic there's really not a lot of difference, just a bit bass light and mid-treble bright, easily EQ'd. Hope Apple never change the mic or input. Or maybe they did later?
Just a note: The maximum frequency you can get from your microphone is half the sampling speed of the AD converter. So half the sampling frequency.(nyquist freq?) (you need two samples to make a minimal "wave")
I've read that an electret microphone (if that is what is used) should be able to detect frequencies in up to 30kHz. If you would want to detect this signal you'd have to sample at 60kHz , i have no idea if you can change your microphone input sample freq, on smartphones .