MATLAB - How do I get the Filter Function to get the output Energy Spectrum? The image was from a question I posted on reddit, so ignore the title.

I'm trying to write a program that plots these graphs


I know that the first plot is just a plot of the source-signal so the "time" domain of the voice signal. I have that down. 
the 2nd plot is the frequency domain signal, which I should be able to get with fft() fcn in matlab? but the plot it gave doesn't look right. 



weird fft plot of source signal - me - a female just saying "aaaaahhhh" for about 15 seconds 

And after I get the right filter function, I do conv??

Thanks in advance.
What u plotted is the complex fft samples.  In order to see the psd in matlab use plot([-1/2:1/ffteln:1/2-1/fftlen]*fs, 10*log10( abs( fftout)./length(fftout)).^2)).  I am assuming of coarse that your signal is real and therefore plotting from -fs/2:fs/2 is standard practice.  For complex signals usually you want to plot from 0:Fs because nyquist is Fs for complex.