Owner`s manual

A-12
Appendix Mark Levinson
Understanding Room Correction
The Nº502’s Room Correction calibration is a powerful tool for optimizing
the sound of your home theater system. We’ve included this section to
provide a little background information explaining why correcting the
room is so important for optimal sound quality.
Sound Wave
Behavior
The listening environment greatly impacts both the way that you hear
sound and the actual sound wave behavior. Outdoors, in the “open air”,
sound typically travels in straight lines, as there is little to obstruct the
sound. However, a room has walls, a floor, and a ceiling, as well as
furniture, door openings, windows, and people – all of which reflect the
sound waves and create resonances within the room.
A reflected sound wave, or reflection, means that a sound wave
bounces, or “reflects”, from any object only once.
Resonance is the phenomena of multiple reflections at a specific
wavelength. All rooms have resonances because sound waves always
reflect from the hard surfaces – the walls, ceiling, and floor – of the room.
Sound Waves in
a Room
In a typical listening room, you hear only a small amount of the sound
directly from the speakers. Most of the sound you hear is reflected off of
the walls, floor, and ceiling, in addition to reflections from the furniture,
windows, door openings, and people present in the room.
To put it simply, think of sound waves as moving objects. The wavelength
of audible sound can be as long 54 feet (20Hz) or as short as 0.667 inches
(20kHz). A good general principle to remember is that if the wavelength is
longer than the size of the object, the wave will pass around the object as
if it wasn’t there. If the wavelength is shorter, strong reflections will occur.
For example, the wavelength of 100Hz is 11 feet, so it will pass around
any person standing in a room. However, the wavelength of 1kHz is only
1.1 feet, so it will bounce, or reflect, off of almost everything solid –
people, walls, furniture – in its path. In short, what this means is that
while the 1kHz sound wave has lots of scattered reflections within the
room, the 100Hz sound wave will actually resonate more because its
wavelength is closer to the size of the room.
DIRECT SOUND
REFLECTED SOUND