MATLAB: How to extract Human response from wave file

Question

Hi all, I have a audio wav file which contains fMRi scanner noise as well as human response. Are we able to extract human response from scanner noise? Since scanner noise has some specific frequency wrt to human response.

Answer 1

You can use filters, probably low-pass filters or band-stop filters, as a fair bit of gradient noise tends to be above the key frequency ranges used by humans. You might need to get a bit creative as the slice repositioning noises are low enough frequency for there to be meaningful overlap. The "clunk" from the coil relaxation is, if I recall, within normal human speech range, but relatively distinctive.

One problem is that a portion of fmri scanner noise tends towards white noise, crossing the key human frequencies. You might be able to use techniques such as median filtering to reduce the white-ish noise.

Darn, it's too late at night for me to remember what causes the white-ish noise. It has been years since I last went in while the scanner was operating, and I could be mis-remembering. On the other hand, the movement of the coils in a device like that is going to generate some turbulent air flow that should come out as white-ish noise, I think.

Note: I was around research mri scanners. No pretty cover, and acoustic noise baffling was not the first priority.