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 ?

  • Brand and model of cell phone please! – placeholder Feb 26 '13 at 2:35
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    In actuality for most modern phones, you are likely to see the lowpass filter in the ADC and related signal chain, often at around .45 FS rather than the microphone. – Chris Stratton Feb 26 '13 at 13:11
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    15kHz isn't inaudible. – user207421 Nov 1 '14 at 22:05

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 MIC's 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:- spectograph recording http://www.geek.net.au/pic/Specgraph.png

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    it's not a binary statement though. That is the microphone may catch high frequency but with more attenuation than other frequencies. The mic has a resonance frequency where it has the maximum sensitivity and also there are circuits that deliberately attenuate inaudible frequencies. Anyway many modern MEMS mics have a flattened response curve (gain as a function of applied frequency) so the test suggested here is the only way to be 100% sure. – fhlb Jul 14 '16 at 17:11

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:

http://blog.faberacoustical.com/2009/ios/iphone/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:

"Narrate's Zoosh software leverages smartphones' speakers and microphones to enable the same data communications between devices that today's NFC provides, but with ultrasonics frequencies that are inaudible to humans." -- Eweek, Slashdot.

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.

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