NT Vamps and Psychoacoustics
dennis mcclain-furmanski
music in NT.Vamps, and the claims in the documentation of
the use of psychoacoustics. Although I understand the
concept, and can verify that they have in fact made use of
some of the techniques, I really don't know the particuals
about how it was accomplished within the program or samples.
Perhaps with some background, some of the whiz-bang sound
program people out there will be able to make use of this.
I'll be glad to fill anyone in further *as time permits*.
I'm in intensive summer school, internship, and working on
two independent projects, all at the same time. I'll check
in here, but I strongly urge anyone interested to get a few
books on psychoacousitcs and read up on it. And if you
haven't heard NT.Vamps, get it and give it a listen. Once
you know what you're listening for, it becomes even better
than the excellent music itself.
============================================
NT Vamps claims to make use of some tricks of
psychoacoustics in order to create effects beyond normal
stereo. In fact, they have done this just as they claim.
Unfortunately, it's hard to tell exactly what they've done
unless you understand the techniques. I've been playing with
psychoacoustic devices and effects for 10 years. I can fill
you in so you can hear them better, because it takes some
training for your ear to hear it. Also, with some idea of
the techniques involved, you can apply these to your own
projects and do the same.
First off: How do we hear 'Three D'? When a sound passes our
head, there's a slight delay as it travels first past one
ear, and then around the head and past the other. The time
delay between them, sensed by both absolute time difference,
and waves shifted slightly out of phase, helps us determine
what direction. Echo, and distortion due to distance, help
us determine how far the source is.
The first trick done in Vamps is delayed phase shift. This
technique was first taken commercial by a company called
Omnisonic about 10 years ago. They built a device which
would split each channel of a stereo signal into two
signals, shift the phase on one of each channel's signals,
delay them slightly, and add them back into the other
channel. The device, called at first a 'Honeybox', later
called Omnisonic 801, sold for about $150.00. Determining
exactly what they did was a bear, becasuse they filled each
device with tar after construction. What this thing did was
simulate electronicly the way your ear heard stereo and
direction, and extended the effect. At first when you listen
to the device, and turn it on and off during playback, all
you hear is a change in volume. To really hear it, you need
to put on headphones. Think about what it sounds like when
you listen to head phones - everything sounds like it's
anywhere from one ear, to the other, all inside your head.
When the effect is kicked in, some of the sound seems to be
*outside* your head, beyond the headphones. After a little
trainign of the ear, you can hear the effect without
headphones. This is why NT Vamps specifies to listen with
headphones. This effect is noticable _IF_ you know what to
listen for. Once you do, it becomes more obvious, and quite
surprising.
Exactly how this was accomplished in Vamps, I can't say, as
I don't have the experience with the software. I suspect
that there are delays built into some playback channels, and
possibly inverted waveforms in some of the samples (or
inverters built into the playback program). This effect
shouldn't be too tough to recreate. Just start playing with
delayed playback, on the order of a few milliseconds, and
with shifted or inverted phase. As the docs state, you can
purchase this ype of effect in a Roland device for $45,000.
I've not heard from Omnisonic in years, so I think they're
gone. But you *can* recreate the effect without hardware. NT
Vamps proves it.
The second trick used is that of low frequency distortion -
'growl' - added to some samples. When a signal comes from
farther away, particularly a low frequency signal, it gets
distorted. The more distortion, the farther away. Using
this, along with the first effect, or just plain delay and
lower volume, gives the effect of distance. A simple aural
illusion.
The third effect is a slight change in pitch and timbre,
simulating doppler shift. When something approaches you, any
sound it emits is higher in frequency. After is passes, the
pitch drops. Timbre changes slightly along with it. Even
though something may approach from behind you, you're used
to thinking of things as approaching from in front of you.
The higher pitched tones seems to be in front of you, due
again to the aural illusion, and to the way you're used to
hearing and thinking about sounds around you.
Although I no longer work with psychoacoustics (I've moved
on to computerized psychomotor testing), I know there are
several good books out there which describe better what is
going on. Look them up.
(@ @)\DynaSoar\___,
ll ll
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An additional note. The stereo imaging effects take place in the high
frequencies. Don't expect your $20 Sony Walkman clone headphones to be able
to reproduce the necessary sound. You'll need some of the better phones, like
Senheisers or higher range Koss, or any of the new 'digital compatible' phones
by any reputable manufacturer. At least until you 'learn' to hear the effect.
After that, you don't need phones at all.
It's worth noting that since the effect is in the signal, it survives recording
and playback. Once it's there, it's there for good. You can make a tape of the
song that the effect is applied to, and it will still be there, and sound
better than a song without it - in some cases, better than the equipment
"should" be able to produce.
Hmmmm.... better than it should be able to be. Kind of like an Apple II,
wouldn't you say?
Steve George
wrote:
>technique was first taken commercial by a company called
>Omnisonic about 10 years ago. They built a device which
>called Omnisonic 801, sold for about $150.00. Determining
>gone. But you *can* recreate the effect without hardware. NT
locating the company. This info is from my 11/26/80 orderform, so
expect it to be dated! :) Oh, the home unit went for $199 + $5 s&h.
Don't know what the car unit went for. Lastly, I just saw the little
logo they were 'touting' as the official label to look for 'on your
records and tapes' which would indicate that the recording was processed
with 'Omnisonic Imager(tm) Sound'. Dennis, have you EVER seen a com-
mercial source which had been processed by this gizmo?
product: 801 Omnisonic Imager (for your home)
" : 801-A " " (for your car)
Omnisonix, Ltd. <-(note the x)
P.O. Box 430
Middletown Avenue
Northford, CT 06472
ph: (203) 239-6213
--
Steve George - still enjoying my 801 after all these years...
--
--
inet: stge...@pnet51.orb.mn.org uucp: kksys!orbit!pnet51!stgeorge
Economists can now prove that the best time to buy anything was 35 years ago.
dennis mcclain-furmanski
[re: Omnisonic 801 imager]
> Dennis, have you EVER seen a commercial source processed by this gizmo?
Only a demo tape the company put out themselves. Never anything by a
regular publisher.
I no longer have my 801 (it went to the ex with the stereo), but I hear
it's still working fine.
I think this would be an ideal application for a DSP card (hint, hint).
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