Power Spectrum with frequency as x-axis and db level as y-axis

Dear all,

I currently have the plot below for a wav file. How can I create a plot with frequency as x-axis and db level as y-axis?

Answer 1

[Mathieu NOE]

hello

from what I see , the x axis units is already in Hz

to convert to dB scale , use this :

y_dB = 20*log10(abs(y_fft))

%see example attached