Create an LTI system from .wav file

Question

Bernardo Rodriguez Jr 2022-4-28

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1706850-create-an-lti-system-from-wav-file

评论： Star Strider 2022-5-6

I'm using Matlab for the first time and would like to know how to use the data from a .wav file to create an LTI system and play that as a sound. So far I have some basic functionality with the program, the DFT, magnitue and phase of the DFT if that makes any difference.

I've attempted something along these lines, but i'm certain it's not the right way to go about it

n = info.BitsPerSample;

y(n) = x(n) + 0.5*x(n-1) + 0.7*x(n-2);

sound(y(n), FS);

For the audio itself I have the following

[data,Fs] = audioread('sound.wav');

info = audioinfo('sound.wav');

sound(data, Fs);

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Star Strider 2022-4-29

@Bernardo Rodriguez Jr — That’s all there is to it. The LTI system estimate simply will do its best to model the transfer function as depicted in the Fourier transform of the sound.

I’m curious as to what your professor wanted to demonstrate with that assignment or lab exercise.

Mathieu NOE 2022-4-29

@Bernardo Rodriguez Jr

well

that wav file is the output of a system , if we can call the system = the guitar ; and your fingers are your inputs

so yes maybe we could build a model of the guitar , but having only the output is not sufficient to know / modelize the guitar ; you can look at matlab function tfestimate to see how input and output data together can help you create a transfer function of a process , that can be transformed to a LTI model .

Also there are techniques to build models directly from time domain data (but always input and output data is needed)

% Reference:

% Subspace Identification for Linear Systems

% Theory - Implementation - Applications

% Peter Van Overschee / Bart De Moor

% Kluwer Academic Publishers, 1996

% Stochastic algorithm: Figure 3.13 page 90 (positive)

% Combined algorithm: Figure 4.8 page 131 (robust)

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Answer 1

Chandra 2022-5-6

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在 MATLAB Online 中打开

Hi,

To pass a signal through a LTI system is done through convolution of transfer function and input signal

[data,Fs] = audioread('sound.wav');
%y(n) = x(n) + 0.5*x(n-1) + 0.7*x(n-2);
b = [1 0.5 0.7]; %numerator coefficients
a = 1;           %denominator coefficients
y = filter(b,a,data);
sound(y, Fs);
%OR%
b = [1 0.5 0.7];
w(:,1) = conv(data(:,1),b);
w(:,2) = conv(data(:,2),b);
y = w;
sound(y, Fs);