Frequency domain analysis of a Audio signal

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Harry_108 2016-4-27

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https://ww2.mathworks.cn/matlabcentral/answers/281261-frequency-domain-analysis-of-a-audio-signal

评论： MANTHAN Rana 2020-6-18

fig2.png

在 MATLAB Online 中打开

hi Matlab experts,

I am relatively new to Matlab.

I have an Audio sample of an electric motor running noise. The Audio file is 25 Sec long, it has got 551251 samples. I did following FFT analysis on the signal.

if true
% code start
y = wavread('audio_signal');
N = lendth (y);
Fs = N / 25;
f = (Fs/N).*(0:N-1);
Y = fft(y,N);
Y = abs (Y(1:N)./(N/2));
Y(Y==0) = eps;
Y = 20log10(Y);
plot (f,Y);
grid on
% code end

on running this code it has created attached figure.

Now I don't understand what kind of information can I extract from this figure. I basically want peak frequency components, various noise information and power information.

Please help me to understand this figure.

thanks in Advance,

Harry

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回答（1 个）

Veera Kanmani 2018-2-28

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/281261-frequency-domain-analysis-of-a-audio-signal#answer_307554

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[audio_in,audio_freq_sampl]=audioread('audio_signal');
Length_audio=length(audio_in);
df=audio_freq_sampl/Length_audio;
frequency_audio=-audio_freq_sampl/2:df:audio_freq_sampl/2-df;
figure
FFT_audio_in=fftshift(fft(audio_in))/length(fft(audio_in));
plot(frequency_audio,abs(FFT_audio_in));
title('FFT of Input Audio');
xlabel('Frequency(Hz)');
ylabel('Amplitude');