I just tried repeating the .mat file export with a speaker playing a 1kHz sine wave. SSPro reported the correct frequency on the graph. I exported a .mat file, and when I was returned to the FFT analyzer screen (which was still running), the sine wave frequency peak drifted down from 1kHz (presumably 44100/48000 * 1kHz). I tried exporting that curve as a .mat and SSpro crashed on me.
Restarting SSpro, I could see the frequency was correct again, but I can no longer export a .mat file, as SSpro continues to crash each time I try. Even after clearing SSpro from the background and restarting the iPod Touch, SSpro seems insistent on crashing every time I try to export a .mat file.
I tried exporting to PDF with the same results, SSpro crashes after one successful export. I was able to capture a screenshot of before and after a .mat export to highlight the 1kHz frequency peak oddity.
I was getting the same results with and without my external headset mic plugged in.
During this session today I was careful to not be running any additional apps, audio or otherwise. This was confirmed by checking background processes by pressing the home button twice to bring up the background screen.
Let me know if you have any questions.