The Language of Sound Control
NetWell has compiled the following terms and their definitions for your refernce. These words represent the building blocks to understanding the science of sound control. For any questions, please call our help desk at 1-800-638-9355.
Absorption
The properties of a material composition to convert sound energy into heat and thereby reducing the amount of sound energy that can be reflected.
Acoustical
The properties of a material to absorb or reflect sound acoustically
Acoustical Analysis
A review of a space to determine the level of reverberation or reflected sound in the space measured in seconds as influenced by the building materials used to construct the space.
Also a study of the amount of acoustical absorption required to reduce reverberation.
Acoustical Environment
The acoustical characteristics of a space or room influenced by the amount of acoustical absorption in the space.
Acoustics
The science of sound that includes the production, transmission and effects of the sound.
Airborne Sound
Sound produced by a vibrating source that radiates waves directly into the air, which is then transmitted through the air as a medium rather than through solid or the structure of the building.
Ambient Noise
Ambient noise encompasses all sound present in a given room, consisting of a composite of sounds from many sources near and far.
Architectural Acoustics
The control of noise in a building space to adequately support the communications function within the space and its effect on the occupants. The qualities of the building materials used to determine its character with respect to distinct hearing.
Area Effect
Acoustical materials spaced apart can have greater absorption than the same amount of material butted together. The increase in efficiency is due to absorption by soft exposed edges and also to diffraction of sound energy around panel perimeters.
ASTM
Acronym for American Society of Testing and Materials
ASTM E84
Test Method for Surface Burning Characteristics of Building Materials. See our Fire section.
Attenuation
The reduction of sound energy as a function of distance traveled.
A-Weighted Sound Scale
A measure of sound pressure level designed to reflect the response of the human ear, which does not respond equally to all frequencies. To describe sound in a manner representative of the human ear’s response, it is necessary to reduce the effects of the low and high frequencies with respect to the medium frequencies. The resulting sound level is said to be A-weighted. The units are measured in dBA. The A-weighted sound level is also called the noise level. Sound level meters have an A-weighting network for measuring A-weighted sound levels.
Audiometer
Instrument for measuring human acuity.
Baffle
A free hanging acoustical sound absorbing unit. Normally suspended vertically in a variety of patterns to introduce absorption into a space to reduce reverberation.
Boominess
Low frequency reflections. In small rooms, thicker acoustical panels with air space behind them can better control low frequency reflections.
Cloud
An acoustical panel suspended in a horizontal position from the ceiling.
Cocktail Party Effect
Sound in a noisy crowded room generated mostly by conversation. Levels rise and fall as people compete with one another to be heard. As the decibels increase, perception of speech becomes increasingly more difficult to understand.
Cycle
One complete oscillation of a sound wave above and below the atmospheric static pressure line. See our Soundwave section of the Academy.
Cycle per second
The number of sound wave oscillations that occur in the time frame of one second.
Damping
The dissipation of vibratory energy in solid media and structures over time or distance. See our Vibration products in our Damping section of the Product Guide and visit our Damping course in our Academy workshop.
Decibel
A unit with no dimension that denotes the ratio between two quantities that are proportional to power, energy or intensity. One of these quantities is a designated reference by which all other quantities of identical units are divided. The sound pressure level in decibels is equal to 10 times the logarithm of the ratio between the pressure squared divided by the reference pressure squared. Refer to our Decibel course in our Academy workshop.
Diffusion
The scattering or random reflection of a sound wave from a surface. Visit our Diffusion course in our Academy workshop.
Echo
Reflected sound producing a distinct repetition of the original sound. See our Reflections course at our Academy workshop.
Field Impact Insulation Class
When measurements are performed in buildings according to the appropriate standards for field measurements, Impact Insulation Class (IIC) is called Field Impact Insulation Class (FIIC). The field test evaluates the dwelling’s actual construction and includes all sound paths.
Field Sound Transmission Class
When measurements are performed in buildings according to the appropriate standards for field measurements, Sound Transmission Class (STC) is called Field Sound Transmission Class (FSTC). The field test evaluates the dwelling’s actual construction and includes all sound paths.
Flame Spread
Classification indicating propagation of flame across a sample compared to flame propagation across concrete panels and red oak. Results are obtained through ASTM E84 or UL 723 test.
Flanking
The transmission of sound around the perimeter or through holes within partitions or barriers that reduces the otherwise obtainable sound transmission loss of a wall or ceiling assembly. Flanking paths can include ducts, switch plates, supply vents, return vents, canisters, pipes, back-to-back electrical outlets, and so on.
Flutter Echo
Short echoes in small reverberative spaces that produce a clicking, ringing or hissing sound after the original sound signal has ceased. Flutter echoes maybe present in long narrow spaces with parallel walls.
Free Field
Sound waves from a source outdoors where there are no obstructions.
Frequency
The number of oscillations or cycles per unit of time expressed in units of Hertz. See our Hertz course in our Academy workshop.
Frequency Analysis
An analysis of sound to determine the character of the sound by determining the amount of sounds at various frequencies that make up the overall sound spectrum.
Hearing Impairment
A degree of hearing loss, temporary or permanent, due to many causes. Hearing loss can be caused by illness, disease, or exposure to excessively high noise levels. Affects 25-50 million people in America. Hearing impairment is the hearing loss of mild, moderate or severe degrees as opposed to "deafness". The hearing impaired are adversely affected by long reverb times.
Hearing Range
16-2000 Hertz Speech intelligibility
600-4800 Hertz Speech privacy
250-2500 Hertz Typical small table radio
Refer to our Hertz chart featured in our Hertz course at the Academy workshop
Hertz
Frequency of sound expressed by cycles per second. Refer to our Hertz course at the Academy workshop.
Impact Insulation Class (IIC)
This is a floor/ceiling assembly rating system that measures the assembly’s ability to block impact sound. The American Society for Testing and Materials test here is called the ASTM E-1007 test.
Intensity
Loudness of sound
Inverse Square Law
Sound levels drop with distance. For every doubling of the distance between a sound signal and the recipient, a 6 dB drop will result. See our course on Decibels at the Academy workshop.
Live End
An acoustical treatment plan for rooms in which one end is highly absorbent and the other end is highly reflective.
Loudness
A listener’s auditory impression of the strength of a sound. The average deviation above and below the static value due to a sound wave is called sound pressure. The energy expended during the sound wave vibration is called intensity and is measure in intensity units. Loudness is the physical resonance to sound pressure and intensity.
Masking
The process by which the threshold of hearing of one sound is raised due to the presence of another. See our Masking course in our Academy workshop and visit our Masking products page.
Mass
Mass is the fundamental property of a material relevant to sound transmission loss through that material. The more massive the material, the greater the sound transmission loss. See our course on Transmission Loss in our Academy workshop, or visit our Walls section of the Applications Guide where we feature the use of our dB-Bloc mass loaded vinyl.
Mounting
Standards established by the ASTM to represent typical installation for purposes of testing materials for sound control.
Noise
Unwanted sound.
Noise Isolation Class
A single number rating of the degree of speech privacy achieved through the use of an Acoustical Ceiling and sound absorbing screens in an open office. NIC has been replaced by the Articulation Class (AC) rating method.
Noise Reduction
The amount of noise that is reduced through the introduction of sound absorbing materials. The level is measured in decibels on a logarithmic basis.
Noise Reduction Coefficient
The NRC of an acoustical material is the arithmetic average to the nearest multiple of .05 of its absorption coefficients at four one-third octave bands with center frequencies of 250, 500, 1000 and 2000 Hertz. Visit our NRC course at the Academy workshop.
Octave
A pitch interval of 2 to 1. The second tone is twice the frequency of the first tone. Visit our Hertz chart at our Sound Test Chamber.
Octave Bands
Sounds that contain energy over a wide range of frequencies are divided into sections called bands. A common standard division is in 10 octave bands identified by their center frequencies of 31.5, 63, 250, 500, 1000 , 2000 and 4000 Hertz.
Pitch
The perceived auditory sensation of sounds expressed in terms of high or low frequency stimulus of the sound. Visit our Frequency chart at our Sound Test Chamber.
Reflection
The amount of sound wave energy that is reflected off a surface. Visit our Reflections course at our Academy workshop.
Resonance
The emphasis of sound at a particular frequency.
Reverberation
Sound after it is ended at the source will continue to reflect off surfaces until the sound wave loses energy by absorption to eventually die out. See our course on Reflections at the Academy workshop.
Reverberation Time
The reverberation time of a room is the time it takes for sound to die off to inaudibility. This is measured as a 60 dB drop once the sound source has stopped. Visit our course on Absorption at the Academy workshop.
Sabin
A unit of sound absorption based on one square foot of material. See our course on Sabins at the Academy workshop.
Septum
A thin layer of material between two layers of absorptive material that prevents sound waves from passing through the absorptive material. See our FBF1M Panels, FabricBloc Panels and our QBS or QBV blankets linked in off Products Page.
Signal to Noise Ratio
The sound level at the listeners ear of a speaker above the background noise. A speaker should be heard at a 15 dB level stronger than the dB level of the background noise in the room.
Smoke Developed Index
Classification that relates to a comparison of smoke development of a particular material compared to concrete panels and red oak. Results are obtained through ASTM E84 or UL723 tests.
Sound
Sound is an oscillation in pressure, stress particle placement, particle velocity in a medium. Sound produces an auditory sensation caused by the oscillation.
Sound Absorption
The property possessed by materials, objects and air, to convert sound energy into heat. Sound waves reflected by a surface cause a loss of energy. The energy not reflected is called its absorption coefficient.
Sound Barrier
A material that when placed around a source of noise inhibits the transmission of that noise beyond the barrier. Also, anything physical or environmental within a room that impairs the ability to communicate.
Sound Level
A subjective measure of sound expressed in decibels as a comparison corresponding to familiar sounds experienced in a variety of situations.
Sound Level Meter
A device that converts sound pressure variations in air into corresponding electronic signals. The signals are filtered to excluded signals outside frequencies desired.
Sound Pressure
The sound pressure is the total instantaneous pressure at a point in space, in the presence of a sound wave, minus the static pressure at that point.
Sound Pressure Level
The sound pressure level, in decibels, of a sound is 20 times the logarithm of the base 10 of the ratio of the sound pressure to the reference pressure.
Sound Transmission Class (STC)
This is a rating for doors, windows, enclosures, noise barriers, partitions and other acoustical products and assemblies. The rating measures the ability of the product or assembly to guard against transmission of sound. Visit our S.C. course at our Academy workshop.
Spectrum
The description of a sound wave’s components of frequency and amplitude.
Speech Intelligibility
The ability of a listener to hear and correctly interpret verbal messages.
Speech Privacy
The degree to which speech is unintelligible between offices. Ratings include confidential, normal, and minimal.
Time Weighted Average
The yardstick used by the OSHA to measure noise levels in a workplace. It is equal to a constant sound level lasting eight hours that would cause the same hearing damage as the variable noises that a worker is actually exposed to.
Ultrasounds
Sounds with a frequency pitch higher than 20,000 Hertz.
Vibration
Vibration is a force which oscillates about some specified reference point. See our Vibration course in our Academy workshop.
Vibration Isolation
A soundproofing treatment designed to disconnect a vibrating source from structure to help isolate the noise.
Volume
The cubic footage of a space bounded by walls, floors and ceilings determined by multiplying the length, width and height of the room.
Wavelength
Sound that passes through air produces motions of compression and refraction. Wavelength is the distance between two identical positions in the cycle. Lower frequencies will possess longer, flatter noise waves. Visit our Soundwave course in our Academy workshop.
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