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_ Appendices
Appendix A: Sonic Holography"
Sonic Holography is a unique process
which enhances the three-dimensional
effects and realism of stereo sound.
To understand the benefits of this circuit,
we must first understand a problem in
obtaining accurate sound reproduction.
In a stereo system, both ears hear the output
from both speakers. The left ear hears sound
from the left speaker and from the right
speaker. To see the problem with this,
compare what happens when listening to a
live musical performance:
During a concert, each ear will receive
one direct sound arrival. For example, a
cymbal crashes, both ears will hear it and our
brain tells us accurately the position of the
musician.
In a stereo recording of the concert, this
cymbal crash will be heard from both
speakers. Our left ear will hear the left
speaker, which is fine, but it will also hear
the crash from the right speaker. The extra
arrival tends to confuse our accurate sense of
positioning, giving a general feeling that the
musician might be over there "somewhere".
An example of this effect is if you use a
good pair of headphones. The stereo effect is
more pronounced because the left ear only
hears the left headphone, and the right ear
hears only the right headphone with no
extra arrivals.
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To summarize:
1.
A real musical event will create only two
direct sound arrivals,
one at the left ear and
one at the right.
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2. Stereo playback will give four arrivals,
as
both speakers are heard by each ear.
These second sound arrivals reduce our
naturally accurate sense of positioning, used
for listening pleasure and self preservation.
The Sonic Hologram circuit was designed
to cancel out the unwanted second arrivals.
The left ear will mainly hear the left speaker
and the right ear mainly hears the right
speaker.
This is accomplished by sending a
complex crosstalk signal from the left and
right speakers, in addition to the normal
program. These extra signals are virtually
identical to the unwanted second sound
arrivals but they are out-of-phase with them
and they cancel each other out.
The result is a more three-dimensional
and wider soundstage, where the positioning
clues are restored. In a way, the musicians
have been freed from the confines of the flat
plane between the speakers. You will perceive
them as playing forward or playing behind
the speakers or to one side or the other, not
just somewhere in between.
We recommend that you experiment
with its effect, remember that you are
listening for a more accurate sense of the
location of the different musicians.
As the Hologram works by phase
cancellation of the unwanted second sound
arrivals, accurate speaker positioning is
required to make sure that the left speaker is
the same distance away from you as the right
speaker. You must follow the speaker
placement on Page
13
to get the best results.
This is the same as any standard stereo
system only with more care taken to position
the speakers accurately.
Sonic Holography is a registered trademark of Carver Corporation.
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