Infinitely recursive perverts....

{SNIP}

If the operation is not done in real time then I would simply record it
as a waveform and then speed it up by a factor of about 50 to 100 to
move the 0.5-40 Hz frequencies into the 25-2000 or 50-4000 Hz range that
humans can hear well. This would pretty interesting I think, and I
would love to receive any WAV files of brain recordings.

Sarn's reply:

The only trouble with speeding thing up, is the fact that you shorten the
damn things as well, and we get the old "chipmunks"-Alvin, Simon and
Theodore, whilst Dave looks onward, agast. :o)

In other words, harmonic quality is lost.

Seriously, however, we can use a newer form of sonic alchemy, and
"silly-puttying" around with sound called "time stretch".

This involves the computer, cutting up the wavefrom into little "carrot
slices", and working out what goes in the middle, on average, with some, or
little overlap.

I would dearly love to know how long this one has been around for.

With extreme time stretches, we generally get some "assumed" information, as
any system operating so, HAS to, by the very nature of time stretch-we're
inventing something that really wasn't there in the first place-the effect
is, very much, in fact, an illusion.....

Thus, we would very probably need some VERY fine data resolution for
gathering these brainwaves information, to get anything realistic.

Extreme time stretched can, however, be used for some pretty "nifty"
effects, so it really becomes a play off between what's actually THERE, and
what we WANT to hear.

Which do you prefer?

{SNIP}

If it is to be done in real time then I would still try to go for a 50
to 100 speed up by simply moving all the frequencies up by that factor
but in this case the piece would last 50 to 100 times longer. There are
several ways to do this, but using FFT to make a spectrum and then
generating a waveform to play from the adjusted frequencies is the most
accurate.

Sarn's reply:

Correct me if I am wrong, but did you mean to say "shorter"?
We downscale time when we up scale frequency-they are inversely related.

I have, BTW, heard whale moanings sped up 15 times, and these sound very
much like birds chirping.

I wounder if birds chirping slowed down sounds like whales?

In a physical model, there is more to the story than time stretching and up
sampling-we are applying an oversimplification to an inherantly more complex
model.

So, would a Jack Russel terrier dog, slowed down, and time compressed, sound
anything likem a Rottweiller?

{SNIP}

I have been doing vipassana meditation for about a year and I think that
I could now have some measure of control over what frequencies I make
and maybe make single tones with a little bit of practice and would love
to get involved in such a project. I see that you are in NZ the same as
me. Where is your friend? I am in Auckland, telephone (09) 419 0073.

Sarn's reply:

I am in New Zealand, also, and my, how uncanny!

I have three other friends, both interested in microtonal music-Peter Brock,
a very interesting guy, but a man who's handwriteing is so damn messy that
it took me about 2 hours to dechipher his letter to me, and even then, this
was with only about 65% comprehension.

The other two are Alan Wells, who writes for the Listner, and is absolutely
BRILLIANT in English, and a man called Keith Austin, who can play about 6
instruments, but is primarily a keyboard player-and a blooming good one, as
well-I have seen him on the grand piano.

He's brilliant.

{SNIP}

Thinking of feedback, don't play the output too loud and too near the
person or you might generate a feedback loop and make an almighty squeel
in the person's brain :-)

Sarn's reply:

This is, actually, not as crazy as it sounds.
I was talking to my old, randy, but very wise Uncle in Paekakariki
(Paekakariki in Maori="The pearch of the little green parrot"), and we were
talking about a series on T.V. called "Sex, lies and videotape", about a man
who tapes himself and watches himself making "beautiful music" with his
girlfriends, of which there were many-he is a really goodlooking type, with
all the phonie patter.

And then, a thought struck me, what if he taped himself watching himself,
and iterated the procedure.

A sort of "recursive pervert".

:o)

Finally, Ray, would you mind if I called you, at some stage?

I know we are all busy, but, we should all make an effort.

Any thoughts?

I am in Wellington, (04) 2355-102.

Sincerely,

Sarn Ursell.

Sarn:
>The only trouble with speeding thing up, is the fact that you shorten the
>damn things as well, and we get the old "chipmunks"-Alvin, Simon and
>Theodore, whilst Dave looks onward, agast. :o)

>In other words, harmonic quality is lost.

No harmonic quality is lost by speeding things up, because the waveform
is identical and so all harmonics are identically placed. It won't
sound like chipmunks because the original frequencies are all very low
and the speeding up is required to bring it into human hearing range.

Obviously the action is over in a fraction of the time if it is sped up
and so a decently long recording is required before it is sped up (but
this can be done at 1000 samples per second or less if you want.

If the frequencies are to be multiplied by 50 to 100 and it is done in
real time, then clearly the speed up factor cannot be applied (as it is
real time) and so in effect each little moment is played 100 times
before moving onto the next. I say in effect because the phases of the
waveforms must keep on developing correctly which is not trivial. This
requires understanding how to use FFT software and a fair bit of
programming, although there may be alternative approaches.

>Finally, Ray, would you mind if I called you, at some stage?
>I know we are all busy, but, we should all make an effort.

I am happy for you to do that. As mentioned my number is (09) 419 0073.

-- Ray Tomes -- http://www.kcbbs.gen.nz/users/rtomes/rt-home.htm --
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