1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Matlab: changing frequency of a .wav file

  1. Sep 12, 2010 #1
    1. The problem statement, all variables and given/known data
    Write a script which plays a Doppler shifted version of a WAV file.

    3. The attempt at a solution

    This is the code for a doppler shifted single frequency:
    Code (Text):
    vs = 1100; % speed of sound in feet per second
    v0 = s*22/15; % speed of the vehicle in feet per second
    fs = 10000; % sampling frequency
    ts = 1/fs; % the sampling period
    f0 = 440;
    td = d/vs; % this is the time for sound to move the distance d
    r = v0/vs; % this ratio should be much less than one of course
    t1 = sqrt(1 - td^2)/r -1; % time vehicle passes you
    t = [ t1-3: ts: t1+3]; % a time base for the signal, with 3 seconds each side
    a = (r^2)*(t-t1)/(1-(r^2));
    b = ((td^2)+(r^2).*(t-t1).^2)./(1-(r^2));
    tau = ((-1)*(2.*a)+sqrt(((2.*a).^2)+(4).*(b)))/(2); % quad form to solve for tau
    y = .5 * sin(2*pi*f0*(t-tau));
     
    What I need is to shift an entire wav file. I tried just setting f0 = wavread('file') but I get an error saying out of memory. Then when I change the f0*(t-tau) to f0.*(t-tau) I get an error saying matrix dimensions must agree.

    I'm not really sure which way it's supposed to be, anyways.

    Thanks.
     
  2. jcsd
  3. Sep 14, 2010 #2
    I'm not sure what you're doing exactly; you need to provide a complete code listing. Something is wrong with your setup if you are unable to use wavread to even read the file.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook