signals addition

Hi, I have the following code.

x1=wavread('speech.wav'); x2=wavread('speech_noise.wav');

I have to do x2-x1

I am getting the error as Dimension mismatch. How to rectify it?

Answer 1

[Richard Brown]

Assuming they correspond to the same sampling rates, truncate one of them to be of the same length as the smaller one:

n1 = length(x1);
n2 = length(x2);

% Assuming n1 < n2
x2 = x2(1:n1)

Or maybe you want to interpolate

x2 = interp1(1:n2, x2, linspace(1, n2, n1));

Or maybe you want to refer back to your other question: http://www.mathworks.com/matlabcentral/answers/36587-adding-of-signals

[Sivakumaran Chandrasekaran]

Hi Richard,

It works well. Thanks for your support. I tried the first method of yours. I shall check with the speakers and get back to you.

[Sivakumaran Chandrasekaran]

Hi Richard,

My code is

x1=wavread('speech.wav');

x2=wavread('speech_noise.wav');

v=x1-x2

x1 is clean voice. x2 is clean+noise.

will i get 'v' as noise signal alone

[Richard Brown]

It depends - is x2 a modified version of x1? And if so, why is it a different size?

[Sivakumaran Chandrasekaran]

i am speaking inside a room ... x1

i am speaking the same content in a crowd(noises)....x2

Answer 2

[Sk Group]

Signal Addition function in MATLAB

MATLAB CODE:

function [y n] = sigadd(x1,n1,x2,n2)

if n1(1)< n2(1)

a = n1(1)

x1 = [zeros(1,abs(n1(1)-n2(1))) x1]

else

a = n2(1)

x1 = [zeros(1,abs(n1(1)-n2(1))) x1]

end

if n1(end)>n2(end)

b = n1(end)

x2 = [x2 zeros(1,abs(n1(end)-n2(end)))]

else

b = n2(end)

x2 = [x2 zeros(1,abs(n1(end)-n2(end)))]

end

n = a:b;

y = x1+x2;

Signal Addition function (Alternate Method) in MATLAB

MATLAB CODE:

function [y n] = sigadd_another_method(x1,n1,x2,n2)

n = min(min(n1),min(n2)):max(max(n1),max(n2));

y1 = zeros(1,length(n));

y2 = y1;

y1(find((n>=min(n1))&(n<=max(n1))==1))=x1;

y2(find((n>=min(n2))&(n<=max(n2))==1))=x2;

y = y1+y2;