34 Room Acoustics
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CoustICs
Your Room
This is an area that requires both a little background to understand
and some time and experimentation to attain the best performance
from your system.
Your room is actually a component and an important part of your
system. This component is a large variable and can dramatically
add to or subtract from a great sonic experience.
All sound is composed of waves. Each frequency has its own
wave size, with the lower bass frequencies literally ranging from
10 feet to as much as 55 feet. Your room participates in this
wave experience like a swimming pool with waves reflecting
and becoming enhanced depending on the size and shape of
the room and the types of surfaces in the room.
Remember that your audio system can actually generate all of
the information required to recreate a sonic event in time, space,
and tonal balance. Acoustically, the role of an ideal room
would be to neither diminish nor contribute to that information.
However, nearly every room does so to some degree.
Terminology
Standing Waves
Sound coming from a subwoofer bounces around in a room until
a pattern emerges—this is called a standing wave. Typically,
this is only a problem with frequencies below 100Hz. When
this happens, different parts of your room experience either an
excess or a lack of bass. Standing waves exist in all rooms and
a different pattern exists for different frequencies in the bass.
Some people believe that having a room without parallel walls
will eliminate this effect. The truth is that non-parallel walls only
generate different standing wave patterns than those that occur
in rectangular rooms.
Usually, you excite most of the standing waves in a room by
putting the subwoofer in a corner. Listening position determines
which standing waves you will experience. For instance, if you
sit in a corner you will hear most of the standing waves. This can
be an overpowering experience. Sitting next to a wall can also
intensify the levels of the standing waves that are experienced.
If you still have an excess or lack of bass after adjusting
subwoofer placement and controls, PBK room correction will
help adjust acoustic output of your subwoofer(s) to minimize
undesired acoustic anomalies and optimize the performance of
your subwoofer within your unique listening environment.
Resonant Surfaces and Objects
All of the surfaces and objects in your room are subject to the
frequencies generated by your system. Much like an instrument,
they will vibrate and "carry on" with the music, and may con-
tribute in a negative way to the sound. Ringing, booming, and
even brightness can occur simply because surfaces and objects
are "singing along" with your speakers. This subwoofer’s Tone
Sweep control can aid in identifying and resolving contributions
from resonant surfaces and objects.
Resonant Cavities
Small alcoves or closet type areas in your room can be chambers
that create their own "standing waves" and can drum their own
"one note" sounds. This subwoofer’s Tone Sweep control can aid
in identifying and resolving contributions from resonant cavities.
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