getUserMedia - Audio: Chrome Android cuts Frequencies above 4 kHz(?)

I'm using some code by another student for acoustic communication. It uses the audio live stream input provided by getUserMedia API. The code works fine between 2 PCs. The developer says this is 'cause Chrome for PC cuts frequencies above 15 kHz due to better quality. The same code used on my smartphone (Galaxy S5) with Chrome just let me use frequencies below 4 kHz. I think here are also some filters applied to cut the frequency.

I also tried using the code with Chrome Apps for Mobile using Cordova and the audioCapture plugin to enable the getUserMedia-API. However, the cause for the script and the app should be the same: something in the underlying chromium.

For my research the frequencies are usable, but the original idea was to exchange data in an inaudible range. So I'd like to know why those frequencies are cut off or if there could be another cause.

Philipp