Axtell's Notes: June 30

So today we changed everything. Not quite, but it feels like it because we no longer use PeakData at all. Threshold has completely replaced it. I found the problems that were holding up Threshold (using the negative of the dB of that point for some reason...) and did a lot of testing as to which weighting function works best (A, B, C, D.) I also tried a slight shift on the decibel calculation when using A-, B- and C-Weightings because their functions use a shift to line up their numbers (Remember, none of these functions are perfect because no one has yet found an equation to match the ATH data set.)

I looked at four files (a440.wav, threenotes.wav, fade.wav and mapleleafrag.wav) with each weighting with and without the shift. (All images are of fade.wav)

A-Weighting lost a lot of data that was audible:

Fade.wav - A-Weighting

B-Weighting shows the most data without showing spill:

Fade.wav - B-Weighting

C-Weighting was a close second to B:

Fade.wav - C-Weighting

D-Weighting shows a lot of upper frequency spill, just barely visible here:

Fade.wav D-Weighting

So B without a shift was the winner and now our default weighing function. Here is Maple Leaf Rag using our new and improved Threshold:

Maple Leaf Rag

Compare that to this, the last Maple Leaf Rag I posted from June 25th:

Maple Leaf Rag - June 25

We gained some upper frequency spill, and lost a lot of lower frequency spill. I'll try to clean that up some more tomorrow.

I also did a little bit of updates to the color spectrum to work with Threshold. Tomorrow, I'll be adding decibels everywhere since we have that math working now! Finally.