Rick wrote,
| First, dB as a function of the signal is:
|
| dB = 10log10(power)
| or:
| dB = 20log10(amplitude)
That's good news (because it is exactly what I had guessed) and bad news
(because the guess wasn't panning out, so I wanted to hear something diffe-
rent that would work more reliably).
I knew that bels involved the common log of the power, and that I'd have to
multiply the number of bels by 10 to get decibels, but 10log(amplitude) was
coming up with roughly half the correct figure, so I figured it had to be
10log(amplitude^2) but didn't know why. So thank you for explaining that
amplitude=power^.5, Rick.
The downside is that 20log(amplitude) was exactly what I had guessed, but
when I get the amplitude from Exactaudiocopy (which preserves one more deci-
mal place than Audiograbber), 20 times its common log is always a little
lower (i.e., a greater negative, father below zero) than the peak amplitude
reported by Cool Edit in dB when Cool Edit re-examines the .wav that Exact-
audiocopy saved from the CD track. Sometimes the discrepancy crosses a .1 dB
boundary, and trusting Exactaudiocopy would lead me to overboost and clip if
Cool Edit is right, but it's a pain to run Cool Edit on the .wav files, so I
was hoping to get dependable results from Exactaudiocopy alone.
So which program do I believe?
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