[sdiy] dx, chorus and Spock

[Batz Goodfortune]

Y-ellow Don, gene 'n' all.

At 05:48 PM 8/15/02 +0000, Scott Gravenhorst wrote:
>Don Tillman <don at till.com> wrote:
> >   > From: Gene Stopp <gene at ixiacom.com>
> >   > Date: Thu, 15 Aug 2002 16:23:52 -0700
> >   >
> >   > Do precise waveforms sound better than "sloppy" ones?
> >
> >I have a theory about our sense of hearing: I claim that we can't hear
> >waveforms or harmonics very accurately at all, but we are remarkably
> >sensitive to the subtleties of the *process* that's making the
> >waveform.
>
>Using a square wave, without any filtering to isolate them, I hear
>quite well and quite distinctly the fundamental AND the 3rd harmonic.
>Higher than that, I can't pick them out, but square waves sound, to me,
>very much like a fundamental plus a perfect fifth in the next octave.
>I'm not sure if that's what you mean, but I can hear this.

There is probably something in all of this but if you look at the way the 
human hearing mechanism works, it's really the ultimate in real-time 
fourier transformation. It is therefore almost entirely harmonically based.

I'm going to generalize here and there will be holes but I don't want to 
take up too much time getting into all the nooks and crannies here. The ear 
has millions of tiny little hairs in it. The name escapes me for the moment 
but they are in effect each, a tiny little tuning fork. Each one tuned very 
specifically to a certain frequency. We're not talking double or even 
tripple redundancy here. It is uncertain from case to case how many of 
these hairs share the same frequency but, that ringing you get in you ears 
some times, thats one of these little hairs folding over and possibly 
becoming non-functional.

Each of those hairs is attached to a nerve. The millions of nerves become a 
nerve bundle and feed the millions of amplitude signals into the sound 
processing region of the brain. The brain in it self being a neural network 
of some 10 billion neurons. All controlled by a plethora of chemical 
operatives called neurotransmitters. When the millions of signals enter the 
brain and form along neural paths they form conceptual groupings. A given 
sound will produce a pattern of neuronal firings. When that pattern is 
close to or exactly the same as something we recognize we call that a 
memory. If that happens to be the memory of something we remember as 
dangerous then it will also trigger patterns that need a response. etc etc.

So each of these hairs would represent a single sine wave. What ever it is 
that we perceive at that level, it is only the amplitude of that sinewave. 
Therefore, in theory you're right. We can't actually hear a sine wave as 
such. BUT! We should be able to hear combinations of harmonics since 
anything other than a pure sine wave would involve more than a single tuned 
hair. (assuming here we've removed the redundancy factor and there is 
theoretically 1 hair per frequency.)

Of course the real world is full of artifacts from the colouring of the 
sound by your ear canal and the environment, to the health of your ear's 
components. A loud sine wave may sound entirely different as adjacent hairs 
get energized and this becomes distortion.

The brain actually hears in mono. The perception of stereo hearing is that 
some of that audio information is transformed into spatial information. The 
sound and the direction it comes from are actually two different things. 
Evolutionary wise, our sense of hearing grew from our sense of touch. Some 
of Earth's life forms still have no ears and communicate solely by feeling 
vibrations through their skin. And this is how the ear evolved.

There is a curious device which is made primarily for learning but is used 
for the deaf as well. It's like a set of headphones but has two tiny 
electrodes. There is something like 3KV potential developed across these 
electrodes. I do not know what that feels like but the thing is that when 
it's modulated with audio, you can actually hear it. Even if you're ears 
are completely stuffed. In fact you can put the thing on the tip of your 
finger and hear it. Once the brain realizes that the sensation closely 
matches that of sound, it passes that information automatically to the 
audio processing region of the brain and you hear it rather than feel it.

The brain is an amazing device to say the least. The same can be done with 
sight. Where a blind person can be hooked to a television camera which 
controls little solenoid devices worn against the skin on the person's 
back. Forming a dot matrix. Very crude but with a little getting use to, 
the person can begin to navigate as the brain learns to interpret the 
feeling with the optic part of the brain instead.

So there may well be something in it but the brain is a conceptual engine. 
You have to expose it to the concept of harmonics before it can learn the 
conceptual relationships.

> >So I'd say that precise oscillator processes sound better than sloppy
> >ones.
>
>If things like *perfect* sawtooth waves sound "better" (highly
>subjective statement I think), then why in God's name would we EVER
>want to filter?  Using a filter changes the harmonic structure such
>that in most cases, the resulting wave is not a perfect anything.  But
>we do use filters.  Why?  Because doing so gives us a sound that is
>correct for our purpose at the moment.

Or you could ask why a bunch of bent up sine waves sound good out of a DX7. 
Which can't actually make a pure tone of the strictly geometric kind.

>Perfect waveforms do have their purpose, such as sweep generators, or
>slope generation for accurate measuring circuits.  But this is more in
>the field of instrumentation, not instruments.

And of course the original synthesizer, the RCA music synthesizer now at 
Princeton. (Or at least it was) Was in fact more like a Kawai K2K than a 
Moog. The reason we use these wave forms is not because they are pure but 
because they are relatively easy to generate. But if you're looking for 
further evidence to back the case, what about a Korg DW8000 etc? I don't 
even think it generates a pure wave form. It's DCO is a selectable 
digitized wave form. Or what about ye olde PPG?

I contend that because of the workings of the human ear and it's associated 
neurology, Synthesis is all about harmonics. Nothing else really matters 
too much.

Be absolutely Icebox.

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