Study of benefits of SACD/DVD-A
Penury
about "high resolution" devices. The following is excerpted from that
presentation:
Adding ultrasonics to a recording technique does NOT improve time
resolution of typical signals – either for imaging or precision of
tempo. The presumption that it does is based on a misunderstanding of
both information theory and human physiology.
Karou and Shogo have shown that ultrasonic harmonics of a 2kHz signal
are NOT audible in the absence of external (non-human) intermodulation
distortion.
Their experiments put a limit on the possibility that a physiological
non-linearity can make ultrasonic harmonics perceptible. They find
that such a non-linearity does not exist at ultrasonic sound pressure
levels below 80dB.
All commercial recordings tested by the author as of 6/1/03 contained
either no ultrasonic information, or ultrasonic harmonics at levels
more than 40dB below the fundamentals.
Our experiments suggest that the most important source of audible
intermodulation for ultrasonics is the electronics, not in the
transducers.
Some consumer grade equipment makes a tacit admission of the
inaudibility of frequencies above 22kHz by simply not reproducing
them. Yet the advertising for these products claims the benefits of
“higher resolution.â€
Even assuming ultrasonics are audible, loudspeaker directivity creates
an unusually tiny sweet spot, both horizontally and vertically.
End of excerpt. The URL is:
http://world.std.com/~griesngr/
Scroll down to Banff at the end. Lots of other info here also.
-=Bill Eckle=-
ab...@wmeckle.com
Vanity Web pages at:
http://www.wmeckle.com
Arny Krueger
news:SFK6b.186599$2x.5...@rwcrnsc52.ops.asp.att.net
(quoting http://world.std.com/~griesngr/intermod.ppt )
"All commercial recordings tested by the author as of 6/1/03 contained
either no ultrasonic information, or ultrasonic harmonics at levels
more than 40dB below the fundamentals."
It is pretty easy for people to demonstrate to themselves that ultrasonic
components of natural sounds aren't audible even when they are at higher
levels than the fundamentals.
" Even assuming ultrasonics are audible, loudspeaker directivity creates
an unusually tiny sweet spot, both horizontally and vertically."
Most loudspeakers have response that rolls off very rapidy above 16 to 25
KHz