# How do I create a frequency waterfall plot from an impulse response?

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Braedon Hall on 5 Aug 2019
Answered: Navya Seelam on 8 Aug 2019
Hi,
I am using the following code to plot magnitude from an impulse response. I would like to plot a waterfall showing amplitude over frequency over time, but I can't seem to make it work.
If anyone could suggest a solution that would be incredibly helpful.
Thanks
info = audioinfo('IR.wav');
Fs = 44100;
t = 0:seconds(1/Fs):seconds(info.Duration);
t = t(1:end-1);
NFFT = length(y);
Y = fft(y,NFFT);
Fy = ((0:1/NFFT:1-1/NFFT)*Fs).';
magnitude = abs(Y);
dB_mag=mag2db(magnitude);
figure(1)
plot(Fy(1:NFFT/2),dB_mag(1:NFFT/2))

Navya Seelam on 8 Aug 2019
Use waterfall function to obtain waterfall plot.
t=0:1/Fs:info.Duration;
t= t(1:end-1)';
Z=[dB_mag(1:NFFT/2) Fy(1:NFFT/2) t1(1:NFFT/2)];
waterfall(Z)
However, the magnitude obtained from fft corresponds to a particular frequency and does not have any time stamp. So, the magnitude obtained from fft can be used to visualize amplitude over frequency but not amplitude over time or frequency over time.