Building Utilities 3 | Glossary of Acoustical Terms
Glossary of Acoustical Terms
Terms in this set (85)
The science of sound, including its generation, transmission and effects of sound waves.
The technology of designing spaces, structures and mechanical systems to meet hearing needs.
The study of how sounds are created, transmitted and received.
An oscillation in pressure of the atmosphere which is capable of being detected by the human ear.
The overall environment, interior to exterior, that affects the acoustic condition of the space of structure under consideration.
The use of acoustical absorbing or reflecting materials or sound-isolating structures to improve or modify the acoustical environment.
The resistance to the flow of acoustical energy, measured in rayls at specific frequencies, affected by density and fiber diameter.
The science and technology of controlling sound in and around buildings.
The ability of a material to absorb acoustical energy. Measured in sabins. The product of area (s) and absorption coeffecient (a). The process of dissipating sound energy by converting it to heat. The reciprocal of sound reflection
The fraction of sound energy impinging on a surface that is absorbed by that surface, usually denoted by a.
Materials that dissipate acoustic energy within their structure as heat and/or mechanical energy of vibration. Usually building materials designed specifically for the purpose of absorbing acoustic energy on the boundary surfaces of rooms or in the cavities of structures.
Sound that is transmitted through air by a series of oscillating pressure fluctuations.
The existing surrounding conditions such as air or surface.
Increase in intensity level of an audible signal produced by means of loud speakers and associated electronic amplification apparatus.
Lessening or reduction of sound intensity, e.g. from 80 db to 70 db.
Noise from all sources in an environment, exclusive of a specific sound of interest.
Sound sensation characterized by more than one frequency.
In sound, the concentration of the conductor molecules to produce a high pitch layer of sound.
Material that carries or transmits energy from one location to another; must be an elastic material.
Transmission of sound along curve surface.
One complete displacement.
Cycles per second (CPS)
Unit of frequency; SI unit (hertz).
Refers to energy dissipation in an oscillating system. A damped system cannot oscillate freely.
The rate at which sound pressure level (in db) decreases when the source of sound is eliminated.
The basic metric unit for describing the magnitude of sound. It is 20 times the logarithm to the base 10 of the ratio of the sound pressure to a reference pressure of 0.0002 dyne/square meter. This reference pressure is considered the lowest value that the ear can detect.
A thin body that separates two areas. In sound, the skin of a partition or ceiling which separates the room from the structural space in the center of the partition or ceiling assembly.
Diffuse Sound Field
A sound field in which the energy arrives at the receiver in a direct path from the source, without any contribution from reflections.
Any change in the transmitted sound signal such that the sound received is not a faithful replica of the original source sound.
Sound waves which have been reflected back to a listener with sufficient magnitude and time delay.
Concentration of reflected acoustic energy within a limited location in a room as the result of the reflection from concave surfaces.
A field free from boundaries that would otherwise tend to reflect sound.
Number of complete oscillation cycles per unit of time. Unit often used is the hertz.
The lowest frequency present in a complex tone.
A rapid succession of echoes caused by reflection of sound back and forth between two parallel walls.
Behaviour of sound waves likened to that of light rays and the law that apply.
A component of sound containing more than one frequency which is an integral multiple of the lowest frequency.
The subjective response to sound, including the entire mechanism of the external, middle and internal ear system and the nervous and cerebral operations that translate the physical stimuli into meaningful signals.
A measure of frequency
Noise of the frequency less than 20 cycles per second, below the normal lower audible limit of the human ear.
The average rate of sound energy flow per unit area in a direction perpendicular to the area.
Ten times the logarithm of the ratio of sound intensity to a reference sound intensity.
Inverse Square Law
At a distance from a source, under free-field conditions, sound intensity varies inversely with the square of the distance from the source, resulting in a decrease in sound pressure level of 6 db for each doubling of distance.
Sound caused by pulsations of liquid pressure about the mean static pressure.
The subjective attribute of an auditory sensation.
The obscuring or covering up of one sound by another.
Any unwanted sound, it is annoying and interferes with speech and hearing, or intense enough to cause hearing damage.
Noise Isolation Class
A single number rating derived in the same manner as Sound Transmission Coeffecient (STC) based on Noise Reduction.
The Reduction in level of unwanted sound by any several means (e.g. distance in outdoor space, by boundary surface absorption, by isolating barriers of enclosures, etc.)
A frequency band whose upper limit is twice the lower limit; a division of the audible frequency range, the center frequency of which is twice that of the preceding band center frequency. The standard acoustical octave bands are centered at 16, 31.5, 63, 125, 250, 500, 1000, 2000, 4000 and 8000 hz.
Component of high frequencies.
Unit of loudness level.
Attribute of an auditory sensation which enables us to order sound on a scale extending from low to high frequency.
Vibration produced at a single frequency.
Unit of specific acoustic impedance or equivalent characteristic acoustic impedance.
The resultant sound energy returned from a surface that is not absorbed or otherwise dissipated upon contact with the surface.
A state in which the forces of oscillation of a system occur at or near a natural frequency of a system.
The persistence of sound in an enclosed space as a result of repeated reflection or scattering of sound.
Reverberation Sound Field
Sound that is reflected from the boundaries of and furnishings within an enclosed space.
The time in seconds required for a sound to decay, roughly speaking to inaudibility after the source ceases. (Strictly the time in seconds for the sound level at specific frequency to decrease 60 db in level after the source stops).
The measure of sound absorption of a surface equivalent to a square foot of perfectly absorptive material; unit of measure of acoustical absorption.
A unit of how loud sound is perceived; it is a non-SI unit.
Materials that have the capacity to absorb sound, such as acoustical tile and panels, carpets, draperies, upholstered furniture, etc.
Designing and equipping a space for effective retention of desirable sounds and maximum relief from undesirable acoustical effects.
Acoustical phenomenon which cause sound waves to be bent or scattered around.
When sound travels in all directions.
The rate at which acoustic energy is radiated. Usually measured in watts.
The fluctuation of pressure about atmospheric pressure. Usually measure in micropascals.
The origination of transmission of sound energy.
Refers to the beneficial reinforcement of a sound signal provided by sound-reflecting surfaces or by a loudspeaker system.
The use of structures and materials designed to reduce the transmission of sound from one area to another.
The propagation of sound energy through various media.
Sound Transmission Class
A single number rating of the sound insulation value of a partition, door, window, etc.
Sound Absorption Coeffecient
The fraction of sound energy absorbed or otherwise reflected by a surface.
Sound Transmission Loss
The difference in decibels of the sound pressure level on the receiver side of a barrier or partition from that on the source side.
A slight offset in angle from a flat plane such as walls or ceilings.
Sound transmission through solid material by means of vibrations of waves in the material.
Related to condition of the brain and sense organs rather than direct physical actions.
Threshold of Audibility
Minimum sound pressure level that is capable of evoking auditory sensation.
Threshold of Pain
The minimum sound pressure level of sound which stimulates the ear to the point at which discomfort gives way to definite pain.
The subjective response of the ear to the pitch of a sound.
Sound above the audible range, frequency greater than 20,000 cycles per second.
Velocity of Sound
The rate of travel of sound in a given medium.
The shape of the graphic representation of a sound wave.
The spherical surface of the wave as it travels out in all direction from the source.
The distance sound wave travels during each cycle of vibration.
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