multiplying audio signal by using Matlab

I have an audio signal ( of my voice ) .However,I want to multiply it by cosine function.

t=[1:1000];

n=cos(2*pi*fc*t);

[y fs]=audioread('message.wav');

How can I do that ?

Answer 1

[Star Strider]

The cosine signal must be the same size as ‘y’.

One way to define it as such:

t = linspace(0, 1, fs);

Then create the cosine funciton to be what you want.

Try this:

t = linspace(0, 1, fs);
fc = 440;
n=cos(2*pi*fc*t).';
y_new = y .* n;
sound(y_new,Fs)

[Gentle EE]

It gives me an error massage saying

Matrix dimensions must agree.　in y_new = y .* n;

[Star Strider]

Try this:

y_new = bsxfun(@times, y, n);

The size of ‘y’ was not specifically stated.

[Gentle EE]

oh sorry I'm pretty new to the matlab

The size of ‘y’ is　　 360856 2　

and for this command y_new = bsxfun(@times, y, n); it gives me an Error message.

Non-singleton dimensions of the two input arrays must match each other.

sorry to bother you

[Star Strider]

Then define ‘t’ as:

t = linspace(0, 1, size(y,1));

That will equalise their lengths. You will need to define your cos call correctly to produce the result you want.

One possibility that may make that easier:

t = linspace(0, 1, size(y,1))/fs;

Experiment to get the result you want.

Remember that the cos call must produce a column vector.

The easiest way to do that is to use the (:) subscript convention to force ‘t’ to be a column vector:

n=cos(2*pi*fc*t(:));

This assumes that ‘fc’ is a scalar.

[Gentle EE]

Thank you so much !

[Star Strider]

As always, my pleasure!