Frequency domain analysis of a Audio signal

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

Answer 1

[Veera Kanmani]

[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');

[arshitha femin]

thank you,its of great use

[neelaksh sharma]

is there any inbuilt function to find out the value of peaks in the graph? findpeaks not working in this ..

[Veera Kanmani]

you can try 'max' function

[Pablo Talamantes Hernandez]

Do you know how to get the dominant frequency from the audio file?

[Vikas Ingle]

Why hold function is not working on this code?

[Paryul Jain]

How to get the dominant frequencies , so that they can be further used in the code?

[MANTHAN Rana]

What is the unit of 'Amplitude' in label y?