On 07/18/2011 06:18 PM, Stefan Schreiber wrote:
Now, it turns out that one of the techniques for projecting sound into
space based on the auditory system is something called HRTF, or
head-related transfer functions, where the frequency or spectral
characteristics of a broadband audio signal, like speech or music,
will vary depending on the angle relative to the ear canal. And that’s
because of the structure of the head and the outer ear, and the
shoulders—everything. And by understanding how that changes, we can
take advantage of HRTF to create sounds in three-dimensional space,
from a perception standpoint, that aren’t actually coming from speakers.
Which means that they are probably using HRTF techniques. Because HRTF
is an individual parameter, they would have to use some form of
"standard" HRTF, as long as they don't perform individual measurements.
For me, the interviewer didn't ask the right questions.
quite obviously, the interviewer either doesn't have much insight into
surround sound psychoacoustics as a whole, or he's deliberately playing
dumb for the (dubious) benefit of his readers.
And again, that’s not just amplitude.
master of suspense. to the uninitiated, this wording implies high magic.
to the slightly more initiated, the word "phase" begins to glow in deep
blue letters on the wall, and we have read so many amazing things in our
hifi magazines about phase, and our friends in the pub don't understand it.
So we’re taking advantage of
what we learned there to create this feeling that things are being
projected into space in the D axis, the depth axis.
<sound of coffee being expelled through the nose>
the what?
so this is 4d spacetime, right? x, y, z, and d :) now this funny drone
noise, is that minkowski spinning in his grave?
This < might > be something new, and indeed difficult to obtain with 5.1
or (classical) Ambisonics. (If at all.)
ambisonics is about recreating a sound field (for many listeners).
head-tracked binaural (whether fed over loudspeakers or headphones) is a
single-listener thing.
any cues that will work without head tracking for more than a single
person with known orientation in the room can be tacked to ambisonics
just as well.
However, X-talk cancelling techniques would require close speakers.
i'm not sure about this. from what i've heard, rwth aachen are running a
CAVE with head tracking and binaural feeds delivered by a cube of
speakers (as that is the only layout that wouldn't interfere too much
with their screen configuration). no idea how exactly they do it, but
there should be some papers out there. iirc they can even accomodate
more than one listener. haven't heard it, though.
What I heard that day at SRS was a witch’s brew of breakthrough audio
technologies, a combination of new psychoacoustic depth-rendering
techniques applied through the filter of a game-changing approach to
mixing movie soundtracks that SRS calls Multi-dimensional Audio, or
MDA. Together, they form the basis of CircleCinema 3D, a feature that
will begin appearing in flat-panel HDTVs and soundbars from SRS
licensees in 2012, and perhaps later, in A/V receivers.
this is gibberish.
But the coding of depth cues seems to be something new, and if this
works, it is really impressing.
actually, i don't see that happening for more than one person, without
head tracking.
P.S.: The next surround system has to be independent of speaker
configurations, and to include the 3D/"sphere" aspect. If you can
reproduce distance cues, even better.
distance cues are mostly gimmickry in my opinion. you can fake distance
in a number of ways, but most are really dependent on the spectrum and
envelope of the program material. most aspects of distance encoding are
also orthogonal to most surround techniques, which means they can be
added at will, today. they don't even necessitate a fancy new name.
you could just say "i'm doing crosstalk-cancelled binaual delivery via
speakers using near-field hrtfs as described by menzies and others", or
you could say "i'm using vector-base amplitude panning of anechoic audio
objects as introduced by pulkki, combined with room synthesis based on
well-known algorithms a, b, and c, some lowpass to mimic air absorption
and adaptive resampling delay to obtain doppler shifts".
of course you could also say "we are harnessing ultrasound-triggered
ectoplasm for real 4-d sound projectiong using our proprietary
one-more-dimension-than-your-mum technology". yawn.
it's so friggin' hard to make the walls of the listening room disappear
(with _any_ surround technique) that i don't see how the majority of
consumers would ever respond to distance cues properly, with the
exception of some bumblebee-in-your-ear tricks or depth effects mediated
by visuals. the former are often limited to very specific content, and
for the latter, if you have visuals, then like it or not, mono is
totally adequate and the brain will do the rest (exaggerated, but only
very slightly).
--
Jörn Nettingsmeier
Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487
Meister für Veranstaltungstechnik (Bühne/Studio)
Tonmeister VDT
http://stackingdwarves.net
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