Normalizing vectors to be the same size to retain PSD data
For function call [pxx, f] = periodogram(y_soundsource_data,window,nfft, Fs);
  you can get the pxx = PSD points= vector of y values, and f= frequency points tied 1:1 to the pxx values. 

... this requires that you specify nfft &amp; Fs


You can get y_soundsource_data and Fs&lt;-- sampling frequency, from the audioread function. file[y Fs]= audioread('100-daddy1.wav');
window and nfft are not understood by the periodogram function UNLESS you define them.


y_soundsource_data and Fs are understood, because audioread returns the data metrics. 
nfft - refers to the number of points used in the DFT. A larger nfft value will lead to a better estimation. nfft MUST be an integer. You can't have half a point. 
window = vector of the size of the y_soundsource_data. 1:length_y_soundsource_data
both window and nfft need to be defined before you call the periodogram function. 










keep getting errors with the [pxx,f] = periodogram(_,fs) version of the call. mathworks.com/help/signal/ref/periodogram.html