error using + matrix dimension must agree

y1=audioread('bel.wav');
var = 0.1; 
N=length(y1) ;
noise_1=var.*randn(N,1);
y_1n=y1 + noise_1;
subplot(311)
plot(y_1n)

may I know why I keep getting this error:

error using +
matrix dimensions must agree
error in
y_1n=y1 + noise_1;

Answer 1

[Dyuman Joshi]

Without the data, we can only guess. And the most probable guess is that y1 is a 2D array and using length() with non-vector array results in ambiguous outputs. A better option is to use size().

Try this -

y1 = audioread('bel.wav');
var = 0.1; 
N = size(y1,1);
noise_1 = var.*randn(N,1);
y_1n = y1 + noise_1;
subplot(311)
plot(y_1n)

[Adam Danz]

☝️ +1

Slight improvement in case there is more than 1 audio channel:

noise_1 = var.*randn(size(y1));