I want to increase the FS to 44100 from 8000, when I do so i get an error regarding the size of the "CELL ARRAY" saying "Matrix dimensions must agree". I am using a function as i am recording simultaneously with the recording. Much appreciated.

function recording = audioOI(x,fs)
% audioOI - Simulataneously plays and records the test signal.
%           Uses Parallel Computing Toolbox.
% INPUT:    x - test signal
%           fs - sampling frequency
% OUTPUT:   y - recorded signal
 
time = length(x)/fs;  % play/record time
recObj = audiorecorder;
parfor ii = 1:2
    if ii==1
        recordblocking(recObj, time);
        recording{ii} = getaudiodata(recObj);
    elseif ii==2
        soundsc(x, fs);
    end
end

%% Audio Input-Output 
% y = getaudiodata(recording)
recording = cell(2,1);          % sliced cell array "recording", to store the recorded signal
% load('chirp.mat');            % Create a signal to play and record
% x = chirp;
fs = 44100;                      % sampling frequency
time = 5;                       % signal duration
N = time * fs;                  % number of samples
x = randn(1,N);                 % Gaussian white noise
 
% play, record and plot
recording = audioOI(x,fs);
y = cell2mat(recording);
% plot(y); grid on;
h2 = ifft(fft(y)./fft(x')); plot(h2);

[Walter Roberson]

I bet recording{2} exists and is empty and that is interfering with the cell2mat

[codefanta]

Hello

thank you for the feedback!

I am quite new to MATLAB so i dont quite understand what you mean?

KInd regards

Oliver

[Image Analyst]

Please attach a .mat file with the x and fs you pass into the function, like

save('answers.mat', 'x', 'fs');

then upload answers.mat. We need this because we need to know what you're passing in to the function.

[codefanta]

Hello

I have attached the file below, I hope its what you needed

KInd regards

Oliver

[codefanta]

I sent the wrong file in the first comment, apoligies and the correct one is in this comment

Answer 1

[Walter Roberson]

You have

fft(y)./fft(x')

where y is 40000 x 1 and x is 1 x 220500

The source of the difficulty is that you generate x as 5 seconds of 44100 Hz, but you generate y as 5 seconds of audiorecorder. The default for audiorecorder is 8000 Hz.

Note: when you ask audiorecorder for 5 seconds of 44100, you should not assume that it will return exactly 220500 samples. It would be safer to extract the length corresponding to the shorter of the 2.

[codefanta]

thank you very much for the help