Sound radiated directly into and transmitted through the air

Impervious to audible sound

The intensification and prolongation of sound produced by sympathetic vibration

A vibration induced in one body by the vibrations of exactly the same period in a neighboring body

Airborne sound traveling directly from a source to the listener

A decrease in energy or pressure per unit area of a sound wave, occurring as the distance from the source increases as a result of absorption, scattering, or spreading in three dimensions

The time in seconds required for a sound made in an enclosed space to diminish by 60 decibels

The persistence of a sound within an enclosed space, caused by multiple reflections of the sound after its source has stopped

The rate of decrease of sound pressure level after its source has stopped, usually expressed in decibels per second

The convergence of sound waves reflected from a concave surface

A wave in which the amplitude of the resultant of a transmitted and a reflected wave is fixed in time and ranges from zero at the nodes to a maximum at the antinodes

The phenomenon in which two or more light or sound waves of the same frequency combine to reinforce or cancel each other, the amplitude of the resulting wave being equal to the algebraic or vector sum of the amplitudes of the combining waves

Any sound that is unwanted, annoying, or discordant, or that interferes with one's hearing of something

An unvarying, unobtrusive sound having the same intensity for all frequencies of a given band, used to mask or obliterate unwanted sound

A measure of the efficiency of a material in absorbing sound at a specified frequency, equal to the fractional part of the incident sound energy at that frequency absorbed by the material

A measure of the sound-absorbing efficiency of a material

One of a series of curves representing the sound pressure level across the frequency spectrum for background noise that should not be exceeded in various environments

The perceived difference in sound pressure levels between two enclosed spaces, due to the sound-isolating qualities of the separating barrier as well as the absorption present in the receiving room, expressed in decibels

The level of ambient sound normally present in a space, above which speech, music, or other sounds must be presented to be heard

The sound normally present in an environment, usually a composite of sounds from both exterior and interior sources, none of which are distinctly identifiable by the listener

The interception and conversion of sound energy into heat or other form of energy by the structure of a material, measured in sabins or absorption units

A unit of sound absorption, equal to one sq. ft. (0.09 sqm) of a perfectly absorptive surface

A unit of sound absorption, equal to one square meter of a perfectly absorptive surface

The use of building materials and construction assemblies designed to reduce the transmission of airborne and structure-borne sound from one room to another or from the exterior to the interior of a building

A path for the transmission of sound other than through a floor, wall, or ceiling assembly, such as along such interconnecting structures as ductwork or piping

Resistance to the transmission of sound caused by the inertia and elasticity of the transmitting medium

An acoustic barrier erected in a plenum over a partition to reduce sound transmission between adjoining rooms

Sound transmitted when a surface is set into vibration by the alternating air pressures of incident sound waves

Sound transmitted through the solid media of a building's structure as a result of direct physical contact or impact, as by vibrating equipment or footsteps

Structure-borne sound generated by physical impact, as by footsteps or the moving of furniture

A single-number rating of the performance of a floor-ceiling construction in preventing the transmission of impact noise

A resilient base for mechanical equipment, installed to reduce the transmission of vibration and noise to the supporting structure. Also known as isolation mount

A heavy concrete base for vibrating mechanical equipment, used in conjunction with vibration isolators to increase the mass of the equipment and decrease the potential for vibratory movement

Any of several construction methods, such as the use of staggered studs or resilient mountings, for breaking the continuity of a path through which structure-borne sound may be transmitted from one space to another

A partition for reducing sound transmission between rooms, famed with two separate rows of studs arranged in zigzag fashion and supporting opposite faces of the partition, sometimes with a fiberglass blanket between

A system of flexible attachments or supports that permits room surfaces to vibrate normally without transmitting the vibratory motions and associated noise to the supporting structure

A metal channel for the resilient mounting of wallboard to studs or joists, used in sound-isolating construction to reduce the transmission of vibrations and noise

A flexible metal device for the resilient mounting of wallboard or metal lath to studs or joists, used in sound-isolating construction to reduce the transmission of vibrations and noise