absorption coefficient - the amount of sound energy absorbed by a surface, varies with frequency and it applies to 1 square foot of the material, multiply the absorption coefficient by the square feet of the material to find the sabines of absorption for the given frequency in the room.
anechoic - free of echos - a room that any reflections are greater then 28 dB down from the direct sound
attenuate - reduce the level of a signal
boomy - excessive bass in a system or room, a parking garage would be an example of a very boomy room, imagine trying to mix in a parking garage.
dB - decibel, a unit to describe the difference in power or intensity of a sound - one tenth of a Bel
dBa - Decibels measured with an A weighted contour filter. It is designed the roughly approximate human hearing at 40 phons. It has a peak at around 2khz rolling off the higher and lower frequencies is about 30 dB down at 50 hz
dBc - Decibels measured with a C weighted contour filter. It is about 1.3 dB down at 50 hz it approximates the loudness contour at 100 phons
diffusor - breaks up sound energy and reflects some of the energy back into the room in a controlled manner, there have have been many advances in diffusor technology in the last 10 years in the past it was very difficult to achieve good diffusion of sound.
drywall - gypsum board, trade names include sheetrock
dodecahedron - a 12 sided speaker with a driver in each side used to test room acoustics
bass trap - absorbs bass frequencies, may tuned to a certain frequency or can be more broadband
broadband - covers a wide band of frequencies
inverse square law - The sound pressure level (SPL) will decrease by 6dB each time the distance from the source doubles.
MDF - medium density fiberboard, it is very heavy and dense, made from fine sawdust much finer than particle board
MTC - music transmission class, a wall rating system from US gypsum, see STC
phons - dB level at 1000 hz referenced to human hearing sensitivity
pink noise - random noise with equal energy per octave, usually used as the test signal for a spectrum analyzer
QRD - Quadratic residue diffussor
resilient channel - (RC for short) a z shaped piece of sheet metal that goes between the the wall frame and the drywall. It allow the drywall to vibrate independent of the frame, reducing amount sound transmitted through the wall
room mode - a resonant frequency of a room caused by the standing wave of a room dimension, a square room would put all of the room modes together and cause those frequencies to build up making the room sound boomy and uncontrolled
RTA - Real Time Analyzer, an audio spectrum analyzer
RFZ - reflection free zone
RT60 - a measurement of the time is takes a sound's reverb to decrease by 60 dB in a room
sabine - a measurement of absorption, 1 sabine = amount of absorption from a1 square foot window to the outside
Sonex - a brand of acoustic foam
soundboard - a fiberboard made by Celotex branded SoundStop (more like cardboard fiber then wood particles)
STC - sound transmission class, a dB rating of the amount of sound reduction a material will give, it also applied to wall designs. note that STC only rates a wall down to 125 Hz and walls that perform the same @125 Hz can have quite different performance at lower frequencies. US gypsum has a rating system MTC (music transmission class) that is closer to the real world performance of a wall.
Tectum - an acoustic material made wood fibers and impregnated with silica, good in heavy use areas it can stand quite a bit of abuse
white noise - random noise having uniform distribution of energy with frequency
703 - Owens Corning fiberglass batts compressed and bonded into semi rigid panels 703 has a density of 3 pounds of fiberglass per cubic foot , it comes in 1,2, and 4 inch thickness of 2' by 4' sheets