what is amplitudes of a wav signal...

i need to find amplitudes of a wav file. so how can i approach for it.. i have an idea, just tell me weather it is right or wrong. if it is so, please guide me in correct way...

abs(fft(wavefile))

is this can give amplitudes????

Answer 1

[Daniel Shub]

Assuming that wavefile is an array and not a string with the file name, then what you have will give you the amplitude as a function of frequency. It may make more sense to do:

20*log10(abs(fft(wavefile)))

Answer 2

[Wayne King]

Are you trying to relate the values of the wav file to some physical variable, like volts? If that is the case, then you need to rely on information about how the wave file was recorded.

Just looking at the .wav file in MATLAB is not going to give you that information in the absence of knowing exactly how it was recorded.

[Sandhu]

i am sorry about it. so can you please tell me , what is amplitude of a speech signal. and how we can find it....please tell me some wahys to find it.

thank you.

[Walter Roberson]

Are you looking for amplitude in terms of the voltage passed by the microphone to the "line in" connector? Or are you looking for the sound pressure level? Or the sound intensity level?

If you are looking for voltage, then there is a fairly simple linear relationship that can be calculated, but if you are looking for sound intensity level or sound pressure level, then a fair bit of work has to be done in order to calibrate your microphone response against known volumes or pressures.