DK Ching VD - Sound

sound

the sensation stimulated in the organs of hearing by mechanical radiant energy transmitted as longitudinal pressure waves through the air or other medium

hertz

the SI unit of frequency

pitch

the predominant frequency of a sound as perceived by the human ear

Doppler effect

an apparent shift in frequency occurring when an acoustic source and listener are in motion relative to each other, the frequency increasing when the source and listener approach each other and decreasing when they move apart

decibel

a unit for expressing the relative pressure or intensity of sounds on a uniform scale from 0 for the least perceptible sound to about 130 for the average threshold of pain

auditory fatigue

physical or mental weariness caused by prolonged exposure to loud noises

sound power

the amount of acoustic energy radiated by a source per unit time, expressed in watts

sound pressure

the difference between the actual pressure at any point in the field of a sound wave and the static pressure at that point, expressed in pascals

sound intensity

the rate at which acoustic energy flows through a medium, expressed in watts per square meter

sound level meter

an electrical instrument for measuring sound pressure levels

acoustics

the branch of physics that deals with the production, control, transmission, reception, and effects of sound

room acoustics

the qualities or characteristics of a room, auditorium, or concert hall that determine the audibility of speech or fidelity of musical sounds in it

sounding board

a structure over or behind and above a speaker or orchestra to reflect the sound toward the audience

reflecting surface

a nonabsorptive surface from which incident sound is reflected, used esp. to redirect sound in a space

acoustical cloud

one of a number of acoustic panels installed near the ceiling of a concert hall to reflect sound for improving the acoustic quality of music

acoustical analysis

a detailed study of the use of a building, the location and orientation of its spaces, possible source of noise, and the desirable acoustical environment in each usable area

acoustical design

the planning, shaping, finishing, and furnishing of an enclosed space to establish the acoustical environment necessary for distinct hearing

acoustical treatment

the application of absorbent or reflecting materials to the walls, ceilings, and floor of an enclosed space to alter or improve its acoustic properties

diffracted sound

airborne sound waves bent by diffraction around an obstacle in their path

reflected sound

the return of unabsorbed airborne sound after striking a surface, at an angle equal to the angle of incidence

airborne sound

sound radiated directly into and transmitted through the air

live

highly reverberant or resonant, as is an auditorium or concert hall

dead

without resonance, as is a room free from echoes and reverberation

soundproof

impervious to audible sound

resonance

the intensification and prolongation of sound produced by sympathetic vibration

sympathetic vibration

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

direct sound

airborne sound traveling directly from a source to the listener

attenuation

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

reverberation

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

decay rate

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

reverberation time

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

echo

the repetition of a sound produced by the reflection of sound waves from an obstructing surface, loud enough and received late enough to be perceived as distinct from the source

flutter

a rapid succession of echoes caused by the reflection of sound waves back and forth between two parallel surfaces, with sufficient time between each reflection to cause the listener to be aware of separate, discrete signals

focusing

the convergence of sound waves reflected from a concave surface

noise

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

noise reduction

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

background noise

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; also called "ambient sound"

white noise

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

interference

the phenomenon in which two or more light or sound waves of the same frequency combine to reinforce or cancel each other

absorption

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

sabin

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

metric sabin

a unit of sound absorption, equal to 1 square meter of perfectly absorptive surface; also called "absorption unit"

sound isolation

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

airborne sound transmission

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

structure-borne sound transmission

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

transmission loss

a measure of the performance of a building material or construction assembly in preventing the transmission of airborne sound

flanking path

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

plenum barrier

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

acoustic mass

resistance to the transmission of sound caused by the inertia and elasticity of the transmitting medium; the heavier and more dense a body, the greater its resistance to sound transmission

vibration isolator

a resilient base for mechanical equipment, installed to reduce the transmission of vibration and noise to the supporting structure; also called "isolation mount"

inertia block

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

impact noise

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

discontinuous construction

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

staggered-stud partition

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

resilient mounting

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

resilient channel

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

resilient clip

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