Spectrogram on Android

A spectrogram could display several qualities of sound in a graphical way. It could map out the frequency of the sound component, color-code its intensity at each frequency.

As part of my Embedded DSP lab, we built this spectrogram program on Android platform. It records the sound, use Android NDK package to embed C code into Android program to process the sound with Fourier Transform and outputs its spectrogram.

pic 1

pic 1 shows the spectrogram of human voice, with different harmonics and intensity at each harmonic

The program’s sampling frequency is set at 8000Hz, thus it could detect highest frequency of 4000Hz without aliasing.

This is part of the Embedded Digital Signal Processing (DSP) lab, the code of this program could be found here