15 Apr
2010
15 Apr
'10
4:27 p.m.
On Thu, Apr 15, 2010 at 10:22:42AM +0100, Gwenhwyfaer wrote:
Especially when it's so easy to posit an
experiment to do such testing
with DACs that can reproduce signals up to 192kHz. Simply generate,
additively, some interesting spectra with and without frequency
components above a person's established audibility threshold, and see
if they can be ABX'd. (You'll want to ensure that your DAC isn't
curtailing your frequency response prematurely, of course; you'll also
want to ensure that your speakers can properly reproduce those
frequencies, too, rather than only converting them into heat - which
will certainly affect the tonal nature of the speaker's reproduction
of audible frequencies... so decent crossover filtering for your
woofers is probably advised too.)
And you need to be sure that your ADs, amps and speaker are
perfectly linear and don't produce products in the < 20 kHz
band when given ultrasonic signals only. For the speakers
that will be near to impossible.
There is at least one 'sound spotlight' system that uses
the nonlinear effects of air to produce audible sound at
the place where two narrow ultrasonic beams cross. IIRC
one of the installations in the ZKM lobby (the one with
the spotlight following a random visitor) uses such a
system. It requires insanely high levels.
Ciao,
--
FA
O tu, che porte, correndo si ?
E guerra e morte !