How do I plot a 3-D graph of an audio signal that show whole signal amplitude VS time(s) VS frequency(hz)?

Hi there!

I'm trying to plot a 3-D plot of my audio file that shows the Amplitude, Frequncy(Hz) and Time(s).Can this be done with surf function? What method is the easiest/shortest way to do the task? This is the code I'm using:

[input, fs] = wavread('address.wav');

L = length(input)./fs; % duration of the audio file in seconds

Ts = 1/fs; % sampling period

t= 0:Ts:L-Ts; % time vector

N= length(t); % length of time vector =15360

F= fs/N;

f= (-fs/2):F:(fs/2)-F; % frequncy vector

Thank You in advance!

Answer 1

[Star Strider]

See the Signal Processing Toolbox spectrogram function. It can produce the data you need from your .wav file, and one of the 3D plotting functions (consider mesh, surf, ribbon) can do the plots.

From the spectrogram documentation:

• [S,F,T] = spectrogram(...) returns a vector of frequencies, F, and a vector of times, T, at which the spectrogram is computed. F has length equal to the number of rows of S. T has length k (defined above) and the values in T correspond to the center of each segment.