How to set the audio read from matlab to zero offset?

[pradeept88]

Hi

please help me, i have recorded the sound from microphone using wavrecord instruction but i'm getting its slight below the zero offset please help me how to set it back to zero offset.

Here is my code.

Fs = 10000;
y = wavrecord(5*Fs,Fs,'double');
wavplay(y,Fs);
plot;


this program records sound of 5 seconds from microphone and samples tat at freq 10kHz and stores samples in array y.

But the plot i'm getting is not setted to zero offset plz help.

Thank U

With regards,
Pradeep

 

[amraldo]

What do you mean by zero offset?
The range or y is -1.0 <= Y < +1.0
--
Amr Ali

 

[pradeept88]

i mean the speech is signal is not centered at zero on x-axis its centered at negative point.

 

[amraldo]

It depends on the speech you are recording.
--
Amr Ali

 

[pradeept88]

but if i apply fft to this signal the response goes to negative.

 

[amraldo]

Did you try values other than 'double'?
--
Amr Ali

 

[pradeept88]

tat only changes amplitude values not the offset

 

[amraldo]

Can you share your fft code?
--
Amr Ali

 

[pradeept88]

Ya here it is,

Fs=10000;
NFFT = 2^nextpow2(L); % Next power of 2 from length of y
Y = fft(y,NFFT)/L;
f = Fs/2*linspace(0,1,NFFT/2+1);

% Plot single-sided amplitude spectrum.
plot(f,2*abs(Y(1:NFFT/2+1)))
title('Single-Sided Amplitude Spectrum of y(t)')
xlabel('Frequency (Hz)')
ylabel('|Y(f)|')

Added after 10 minutes:

for all the speech i read it starts frm negative so. fft output is zero.

Added after 2 minutes:

thank u for ur reply amar ali.