Need help modulating an audio file?

I need help modulating an audio file to sound like Darth Vader. What I have so far gets the job done, but the sound isnt very clean. Is there a better way to change the pitch to a lower tone and slow it down without altering the playback frequency. ex.(soundsc(yy,Fs/1.35))

[orig Fs] = audioread('man2_orig.wav'); N=200; echo = orig; for n=N+1:length(orig) echo(n) = orig(n) + orig(n-N); end

 delay1 = round(Fs*0.008); % FIR Delay
 delay2 = round(Fs*0.025); % IIR Delay
 coef = 0.25; % IIR Decay rate
 reverb = filter([1 zeros(1,delay1) coef],[1 zeros(1,delay2) -coef],echo);

yy = atan(5*reverb); soundsc(yy,Fs/1.35);

Answer 1

[Star Strider]

Assuming I understand your Question, there are a couple ways I can think of to do what you want, both requiring the Signal Processing Toolbox. The first is the resample function, and the second is the modulate function (use double-sideband-suppressed-carrier) together with a bandpass filter to pass only the lower sideband.