What is the amplitude unit when we plot wav. files?
56 views (last 30 days)
Show older comments
Lis on 3 Sep 2013
Commented: Mohammed Alkhatib on 12 Jun 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
Edited: Walter Roberson on 3 Sep 2013
Usually wav files are 0 to 255, or -1 x < 1 (notice that is not '<=' 1). See <http://www.mathworks.com/help/matlab/ref/wavwrite.html
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.
More Answers (1)
Daniel Shub on 3 Sep 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.
Mohammed Alkhatib on 12 Jun 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
Find more on Audio and Video Data in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!Start Hunting!