Time changes of sound power spectrum

Hello,

I would like to evaluate power spectrum (amplitude) changes in several tens of seconds length sound record, only on some chosen frequencies. E.g. on 1,5kHz and 2kHz. I need to plot the changes as a time curves. No spectragraph.

V.

Answer 1

[Image Analyst]

Look up help on pwelch() and plot(). Get the spectrum, extract the value at the element corresponding to 1.5 and 2 kHz. Repeat for every spectrum and build up an array, then plot it.