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# generate echo with convolution and cancel it

## generate echo with convolution and cancel it

(OP)
hello guys

i am beginner at using matlab

i want to generate echo on a sound file i recorded in wav and then made echo on it with convolution method.

and the second part cancel the echo

i dont know how to do it in matlab , i know formulas only .

any help i will be thankful

thx

### RE: generate echo with convolution and cancel it

(OP)
thx :)

i have this code for do echo:

#### CODE --> matlab

%working code for echo in conv

x = zeros(1000,1);
x(1) = 1;
x(1000)=1;

z= conv(x,y);
sound (z,Fs); 

i want remove the echo from the sound and get back original sound but with using convolution method only??!!

i tried this method

#### CODE --> matlab

%cancelling

N=25199; % delay in samples

y=z; % Signal with echo

x(1:N)=y(1:N); % First N samples of x and y agree

for i=N+2:length(y)

x(i)=y(i)-0.75*x(i-N); % Inverse filtering

end

subplot(211)

plot(y); % Plot signal with echo

title('SIGNAL WITH ECHO');

subplot(212)

plot(x); % Plot signal without echo

title('SIGNAL WITHOUT ECHO');

soundsc(y); % Listen to signal with echo

soundsc(x); % Listen to signal without echo 

x sound only same as echo one and when reduce N samples to less .... there is echo come over the original one

any help plz??!!!

### RE: generate echo with convolution and cancel it

(OP)
yeah , it a project

i have a work code for cancel the echo:

#### CODE --> matlab

l=max([length(z);length(x)]);
a=fft([z;zeros(l-length(z),1)]);
b=fft([x;zeros(l-length(x),1)]);
c=real(ifft(a./b));
sound(c,Fs); 

it works fine , but they want me use conv function to remove echo , i dont know how :\

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