Positive decibels???
i know that in the digital world the Audio In is from negative value of decibel to 0dB. But i would like to know if its possible to see in positive values from 0dB to forward.
thanksss
Sure. You just have to decide what you want to use as your 0 dB reference amplitude. In digital audio, an amplitude of 1 is used as the 0 dB reference. In measuring real-world sound, the human threshold of hearing at 1 KHz (I think it's something like .0002 microbar) is usually used as the 0 dB reference value. Here's an example using (what I think is) the smallest obtainable nonzero amplitude in a 16-bit signal as the reference value, yielding a scale from about 0 to 90 dB.
thankss Christopher, but if have a sound that has 110 dB what can i do?
the number 32768 is from (2^8)/2??? where do you get this information?
thanksss!!!
110 db/A should be possible.
your above assumption is not correct.
signals in music apps (and in maxmsp) are of a resolution of 32 bit floating
point (or more), which is why you can go over 0db - so unless you need to output
the audio data to a D/A hardware driver, which is only 24 bits, you can go "over".
speaking in decimal, 0db is NOT +-32768, it is +-1.0 .
0.5 is -3.0db/A, and 2.0 is +3.0db/A.
1024.0 already is +30.db/A and should be sufficient for most real life situations
when coding audio effects. going even higher will cause oyu problems when you
need to sum dozens of channels afterwards because there are no dedicated overflow
bits in maxmsp (in opposite to iOS or protools), but thats lesson 3. :D
for now just calculate yourself how much db "over" you can have with +-32767.
if it does not reach 110 db/A, you wont have to worry about it, because that means that
there will also be no 110 db/A audiofiles.
-110
All this post is because i would like to create a basic sonometer. then if i have a sound with 95 dB ... ill have a problem. But i think that should be fine with 0-90 for most of basic sounds.
thanksss for your help!
Hi
You need to do a LOT more research . . .
Yes in digital music there is 0db FS (FullScale) which basically means count backwards from maximumum cause thats all you get, whether it be 16bit or 32 bit . . .
But , decibels are not that simple, and neither are sonometers; nor their relationship . . . you should check that out too . . .
The measurements you will be dealing in will probably be dBV or dBm which you will want converted to phons or sones - this is not exactly a straightforward thing either . . . .
Cheers
MM