# What is the amplitude unit when we plot wav. files?

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Lis el 3 de Sept. de 2013
Comentada: Mohammed Alkhatib el 12 de Jun. de 2022
Hello, I work with bioacoustics and in my analysis I usually use softwares like Raven 1.4 and Adobe Audition. However, I've been urged to apply Matlab in my analysis.
I need to calculate underwater sound pressure levels. I usually take the values provided by Adobe (in dBFS) and perform the necessary conversions and calculations to obtain SPL. In Matlab I need to what is the amplitude unit when I open wav. files.
Can I calculate SPL directly from the wav. file using the amplitude levels and calibration data or do I need to insert a calibration file separately?
Thank you, Lis
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Walter Roberson el 3 de Sept. de 2013
Editada: Walter Roberson el 3 de Sept. de 2013
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Lis el 3 de Sept. de 2013
Thank you for reading my question. I understand that the amplitude range is –1.0 <= y <= +1.0. What I would like to know is if the values contained in this range are voltage values or if they are a normalized plot of voltage values that must be converted before the SPL calculation.
Lis
Walter Roberson el 3 de Sept. de 2013
They are normalized, with -1 to correspond to the minimum voltage that can be produced by the line driver, and +1 to correspond to the maximum voltage that can be produced by the line driver.

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### Más respuestas (1)

Daniel Shub el 3 de Sept. de 2013
Wav files come in two varieties. The first has a range -1 to 1 and the second has the range 0 to 255. For the first 20*log10(x) corresponds to dB FS while for the second 20*log10((x-128)/255) gives dB FS.
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Zhuoyi Ma el 20 de Sept. de 2020
You forgot to divide the x by P0= 20e-6
Mohammed Alkhatib el 12 de Jun. de 2022
he is right you are wrong. he said its dB FS in that case you dont need to divide but if its dBSPL then you have to divide by P0

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