Decibel Levels

[Ron Nossaman]

>Hi Ron, does your little "how loud" have peak hold?  Is it
>digital or analog?

Hi Newton, it's analog, no peak hold, metered -10 to +6 from base scales of
60, 70, to 120 db. There is a slow/fast response toggle, and an A/C
weighting toggle. Truly a no frills listener.

>Discontent minds require "no".

Why?


>I have a real time analyzer for the computer but it is a
>professional program for which I paid lots of money years
>ago.  The electronics tech at Rutgers was able to get more
>and better equalization for the sound system in ten minutes
>with it than he had been able to get during the last ten
>years.  Meat tool.
>-- 
>		Newton Hunt

I'm working on a couple of Windows versions (my first foray into the
bizarre world of Windows programming). They are both intended for piano
research, since I've never detected even a hint of the nearly universal
enthusiasm of the American male for electronic sound systems in my own
self. One is real time and gives you a visual plot of the FFT, and a
horizontal scroll display of the time sequence with frequencies on the
vertical scale, and amplitudes on a color scale. This one is intended for
quick tests of partials produced, and immediate visual verification of
general changes in the spectrum with voicing, duplex muting, and such. It's
mostly working, but on hold while I work on the biggie. The second one is
much more interesting, and isn't intended for real time analysis. It takes
a four second sample from the mic, applies whatever filters I've chosen,
and plots a 3-D perspective grid of the results. The display looks like
those that Jim Ellis reproduced in the Journal with his natural beats
article. I can set the mic level, and trigger level for the record. I can
specify time duration, amplitude, and frequency ranges of the plot from
sliders on screen, so I can zoom in for detail anywhere in the spectrum I
want from 3hz to over 11,000. I've included an ambient noise record and
compensate filter to take those 60hz florescent peaks (and multiples
thereof) and computer fan noises out of the sample. I've got Blackman and
Hamming filters to minimize noise and end effects from the sample, if
necessary, and a linear or log amplitude display, depending on what you
want to see in the spectrum. It will load and save recorded samples for
archival purposes.

At the moment, I'm whacking away at a function that scans the input record
and reports the frequencies and amplitudes of the peaks. It's coming along,
but I have to go back to Kindergarten with the Trig every time I do
something like this. It just doesn't seem to stick to my greasy old brain.
I'll get it though.

Next, I'll want a split screen display to compare before and after samples
of voicing and termination experiments, and a built in file database
management system so I can include piano information and notes with the file.

Eventually, I'll get all this extra stuff figured out, but to date, it's
quite functional and looks like it will prove to be useful and educational
for a long time to come.


Ron N