Introduction
March 1983
Slab-on-grade Construction: a concrete slab poured on
ment process, which provide the data necessary to program,
a prepared ground surface, as opposed to a floor slab above
budget, and initiate design of proposed army construction
projects.
the ground surface (with space underneath).
Proprietary : item or assembly offered as a package by
Sound Lock: a vestibule, with two doors, between a music
one manufacturer only, whose performance is guaranteed.
room and another space, designed to isolate noise.
Reflectivity: the ability to redirect, back into a space, sound
Sound Transmission Class (STC): rating scale for the
waves that strike a surface, as opposed to absorbing the
effectiveness of sound-isolating constructions, based on
waves.
their attenuation at many different frequencies to arrive at
Renovation: construction modification of an existing
one comparative number; however, like NRC, STC does
building for reuse.
not consider low-frequency sound as produced by bands.
Resilient Attachment: a method of attachment to stop
Splayed Wall: a wall at an oblique angle to another; used
transfer of sound and vibration from one material to
for acoustic purposes to diffuse sound and break up
another; provides superior sound isolation.
unwanted echoes.
Reverberation: persistence of sound in a room after the
Standing Wave: an accentuation of sound at specific
source has stopped.
frequencies caused by room dimensions that are equal to
or multiples of each other.
Reverberation Time: for a given frequency, the time
required, after the source has stopped, for the average sound
STC-Rated Ceiling: an assembly consisting typically of a
pressure level, originally in a steady state, to decrease
metal support grid hangers and acoustical tiles, proprietary
60 decibels (in other words, to decrease to one millionth
to a particular manufacturer, whose performance as a
of its initial value).
sound attenuator has been tested by an independent labora-
Room Acoustics: The acoustical qualities--loudness,
tory and found to be in the range of STC 35-44.
reverberance, etc. -- of a room, as determined by its size,
Suspended Acoustical Ceiling: an assembly consisting of
shape and finishes; not to be confused with Isolation or
a metal support grid, hangers and mineral fiber or fiber-
Noise Control.
glass tiles; always NRC-rated, but not always STC-rated.
Sealant, Acoustical: a manufactured, permanently flexi-
Zoning: dividing a building design or building site design
ble material used to fill linear gaps in construction, such
into areas of some functional similarity for planning purposes.
as those at joints between two materials, to eliminate
openings in sound-isolating barriers.
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