Yamaha DSP-AX620 EN - Manual (Page 52)

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SOUND FIELD PROGRAM PARAMETER EDITING
What is a sound field?
What really creates the rich, full tones of a live instrument
are the multiple reflections from the walls of the room. In
addition to making the sound “live”, these reflections
enable us to tell where the player is situated, and the size
and shape of the room in which we are sitting.
■ Elements of a sound field
In any environment, in addition to the direct sound
coming straight to our ears from the player’s instrument,
there are two distinct types of sound reflections that
combine to make up the sound field:
Early reflections
Reflected sounds reach our ears extremely rapidly
(50 ms – 100 ms after the direct sound), after reflecting
from one surface only — for example, from the ceiling or
a wall. These reflections fall into specific patterns for any
particular environment, and provide vital information to
our ears. Early reflections actually add clarity to the direct
sound.
Reverberations
These are caused by reflections from more than one
surface — walls, ceiling, the back of the room — so
numerous that they merge together to form a continuous
sonic “afterglow”. They are non-directional, and lessen
the clarity of the direct sound.
Direct sound, early reflections and subsequent
reverberation taken together help us to determine the
subjective size and shape of the room, and it is this
information that the digital sound field processor
reproduces in order to create sound fields.
If you could create the appropriate early reflections and
subsequent reverberations in your listening room, you
would be able to create your own listening environment.
The acoustics in your room could be changed to those of
a concert hall, a dance floor, or virtually any size room at
all. This ability to create sound fields at will is exactly
what YAMAHA has done with the digital sound field
processor.
Sound Field Program Parameters
DSP programs consist of some parameters to determine
the apparent room size, reverberation time, distance from
you to the performer, etc. In each program, these
parameters are set with values precisely calculated by
YAMAHA to create a sound field unique to the program.
It is recommended to use DSP programs without
changing the values of parameters; however, this unit also
allows you to create your own sound fields. Starting with
one of the built-in programs, you can adjust those
parameters.
Each DSP program has a set of parameters that allow you
to change the characteristics of the acoustic environment
to precisely create the effect you want. These parameters
correspond to the many natural acoustic factors that
create the sound field you experience in an actual concert
hall or other listening environment. The size of the room,
for example, affects the length of time between the early
reflections. The “ROOM SIZE” parameter provided in
many of the DSP programs alters the timing between
these reflections, thus changing the shape of the “room”
you are listening. In addition to room size, the shape of
the room and the characteristics of its surfaces have a
significant effect on the final sound. Surfaces that absorb
sound, for example, cause the reflections and
reverberations to die out more quickly, while highly
reflective surfaces allow the reflections to carry on for a
longer period of time. The digital sound field parameters
allow you to control these and many other factors that
contribute to your personal sound field, allowing you to
essentially “redesign” the concert halls, theaters, etc.
provided to create custom-tailored listening environments
that ideally match your mood and music.
See “Sound Field Parameter Descriptions”.
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