Bldg. Utilitues 3 Flashcards
A longitudinal pressure wave in air or an elastic medium, esp. one producing an audible sensation.
Sound wave
A disturbance or oscillation that transfers energy progressively from point to point in a medium or space without advance by the points themselves, as in the transmission of sound or light.
Wave
A graphic representation of the shape of a wave, obtained by plotting deviation at a fixed point versus time.
Waveform
The distance, measured in the direction of propagation of a wave, from any one point to the next point of the corresponding phase.
Wavelength
A particular point or stage in a periodic cycle or process.
Phase
The maximum deviation of a wave or alternating current from its average value.
Amplitude
The lowest frequency at which a vibrating element or system will freely oscillate.
Fundamental frequency
A vibration having a frequency that
is an integral multiple of that of the fundamental.
Harmonic
A range of wavelengths or frequency between two defined limits.
Band
The number of cycles per unit time of a
wave or oscillation.
Frequency
The Si unit of frequency, equal to one cycle per second.
Hertz
The predominant frequency of a sounds perceived by the human ear.
Pitch
The interval between two frequencies having a ratio of 2:1.
Octave
A surface of a propagating wave composed at any instant of all points having identical phases, usually perpendicular to the direction of propagation.
Wave front
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.
Doppler effect
The velocity of sound traveling through air at approximately 1087 ft
0.3 kmps
The velocity of sound traveling through water at approximately 4500 ft
1.4 kmps
The velocity of sound traveling through wood at approximately 11700 ft
3.6 kmps
The velocity of sound traveling through steel at approximately 18000 ft
5.5 kmps
A subjective response to Sound Indicating the magnitude of the auditory sensation produced by the amplitude of a sound wave.
Loudness
A unit for measuring the apparent loudness of a sound, equal in number to the decibels of a 1000-Hz referenced sound judged by a group of listeners to be equal in loudness to the given sound.
Phon
A unit for measuring the apparently loudness of a sound, judged by a groups of listeners to be equal to the loudness a 1000-Hz reference sound having a intensity of 40 decibels.
Sone
A curve representing the sounds pressure level at which sounds of different frequencies are judged by a group of listeners to be equally loud.
Equal loudness contour
A unit for expressing the relativepressure or intensity of sounds on auniform scale from O for the leastperceptible sound to about 130 for theaverage threshold of pain. Abbr.: dB
Decibel
The sense by which sound is perceived, involving the entire mechanism of the internal, middle, and external ear and including the nervous and cerebral operations that translate the physical operations into meaningful signals.
Hearing
The level of sound intensity is high enough to produce the sensation of pain in the human ear, usually around 130 dB.
Threshold of pain
Physical or mental weariness caused prolonged exposure to loud noises.
Auditory fatigue
An increase in the threshold feasibility, at specific frequencies,caused by normal aging, disease, or injury to the hearing organs.
Hearing loss
The minimum sound pressure capable stimulating an auditory sensation,usually 20 micropascals or zero dB.
Threshold of hearing
The amount of acoustic energy
radiated by a source per unit time,expressed in watts.
Sound power
The acoustic power of a source measured on the decibel scale, equal to 10 times the common logarithm of the ratio of the acoustic power to reference power, usually 10^-12 watts.
Sound power level
An electrical instrument for measuring sound pressure levels. To compensate for the way we perceive the relative loudness of different frequencies of sound, there are three networks: A, B,and C. These networks weight the recordings for different frequencies and combine the results in a single reading. The A-network scale, in dBAunits, is most commonly used since itdiscriminates against the lowerfrequencies, as does the human ear atmoderate sound levels.
Sound level meter
The rate at which acoustic energy flows through a medium, expressed in watts per square meter.
Sound intensity
Sound intensity measured on the decibel scale, equal to 10 times the common logarithm of the ratio of the sound intensity to a reference intensity, usually 10^-12 watts per square meter (10-16 watts per square centimeter.)
Sound intensity levels
The exponent indicating the power to which a base number must be raised to arrive at a given number.
Logarithm
A logarithm having a base of 10.
Common logarithm
A range of frequencies from 15 Hz to 20,000 Hz audible to the normal human ear.
Audio frequency
The difference between the actual pressure at any point in the field of sound wave and the static pressure at that point, expressed in pascals.
Sound pressure
Sound pressure measured on the decibel scale, equal to 10 times the common logarithm of the ratio of the sound pressure to a reference pressure, usually 20 micro pascals.
Sound pressure level
One-millionth (10) part of a pascal.
Symbol: µPa
Micropascal
The branch of physics that deals with the production, control, transmission,reception, and effects of sound.
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.
Room acoustics
A structure over or behind and above a speaker or orchestra to reflect the sound toward the audience.
Sounding board
A non absorptive surface from which incident sound is reflected, used esp. to redirect sound in a space. To be effective,a reflecting surface should have a least dimension equal to or greater than the wavelength of the lowest frequency of the sound being reflected.
Reflected surface
One of a number of acoustic panels installed near the ceiling of a concert hall to reflect sound for improving theacourstic quality of music.
Acoustical cloud
A detailed study of the use of a building,the location and orientation of its spaces,possible sources of noise, and the desirable acoustical environment in each usable area.
Acoustical analysis
The planning, shaping, finishing, furnishings of an enclosed space to establish the acoustical environment necessary for distinct hearing.
Acoustical design
The application of absorbent or reflecting materials to the walls, ceiling, and floor of an enclosed space to alter or improve acoustic properties.
Acoustical treatment
Airborne sound waves bent by diffraection around an obstacle their path.
Difracted sound
The return of unabsorbed airborne sound after striking a surface, at angle equal to the angle of incidence.
Reflected sound
Sound radiated directly into and transmitted through the air.
Airborne sound
Highly reverberant or resonant, as an auditorium or concert hall.
Live
Without resonance, as a room free from echoes and reverberation.
Dead
Impervious to audible sound.
Sound proof
The intensification and prolongation of sound produced by sympathetic vibration.
Resonance
A vibration induced in one body by the vibrations of exactly the same period in a neighboring body.
Sympathetic vibration
Airborne sound traveling directly from a source to the listener. In a room, the human ear always hears direct sound before it hears reflected sound. As ____ loses intensity, the importance of reflected sound increases.
Direct sound
The persistence of a sound within an enclosed space, caused by multiple reflections of the sound after its source has stopped.
Reverbaration
The rate of decrease of sound pressure level after its source has stopped, usually expressed in decibels per second.
Decay rate
The time in seconds required for sound made in an enclosed space diminish by 60 decibels.
Reverberation time
A decrease in energy or pressure per unit area of a sound wave, occurring at the distance from the source increases as a result of absorption, scattering, or spreading in three dimensions.
Attenuation
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.
Echo
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.
Flutter
The convergence of sound waves reflected from a concave surface.
Focusing
One of a series of curves representing the sound pressure level across the frequency spectrum for background noise that shouldn’t be exceeded in various environments.Higher noise levels are permitted at the lower frequencies since the human ear isleess sensitive to sounds in this frequency region. Also called NC curves.
Noise criteria curve
Any sound that is unwanted, annoying,or discordant, or that interferes with one’s hearing of something.
Noise
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.
Noise reduction
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.
Standing wave
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.
Interference
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.
Absorption coefficient
A measure of the sound-absorbing efficiency of a material, equal to the average of the absorption coefficient of the material, computed to the nearest 0.05 at four frequencies:250, 500, 1000, and 2000 Hz.
Noise reduction coefficient
An unvarying, unobtrusive sound having the same intensity for all frequencies of a given band, used to mask or obliterate unwanted sound. Also called white sound.
White noise
The level of ambient sound normally present in a space, above which speech,music, or other sounds must be presented to be heard.
Background noise level
The sound normally present in anenvironmrent, usually a composite of sounds from both exterior and interior sources, none of which are distinctly identifiable by the listener. Also called ambient sound.
Background noise
The interception and conversion of soundenergy into heat or other form of energy by the structure of a material, measured in sabins or absorption units.
Absorption
A unit of sound absorption, equal to one sq. ft. (0.09 sq. m) of a perfectly absorptive surface.
Sabin
A unit of sound absorption, equal to 1 square meter of perfectly absorptive surface. Also called an absorption unit.
Metric sabin
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. Also called sound insulation.
Sound isolation
Sound transmitted when a surface is set into vibration by the alternating air
pressures of incident sound waves.
Airborne 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.
Structure-borne sound transmission
A measure of the performance of a buildingmaterial or construction assembly inpreventing the transmission of airbornesound, equal to the reduction in soundintensity as it passes through the materialor assembly when tested at all one-thirdoctave band center frequencies from 125 to4000 Hz: expressed in decibels. Abbr.: TL
Transmission loss
Three factors enhance the TL rating of a construction assembly:
Mass, separation of layers, and absorptive capacity
A single-number rating of the performance of a building material or construction assembly in preventing the transmission of airborne sound, equal to the average of Its TL values at nine test frequencies.
Average transmission loss
A single-number rating of the performanceof a building material or construction assembly in preventing the transmission ofairborne sound, derived by comparing thelaboratory TL test curve for the material orassembly to a standard frequency curve.Abbr.: STC
Sound transmission class
T or F: The higher the STC rating, the greater the sound-isolating value of the material or construction.
True
Structure-borne sound generated by physical impact, as by footsteps or the moving of furniture.
Impact noise
A single-number rating of the performanceof a floor-ceiling construction in preventing the transmission of impact noise. Abbr.: IIC
Impact insulation class
T or F: The higher the lIC rating, the more effective is the construction in isolating impact noise.
True
A path for the transmission of sound other than through a floor, wall, or ceiling assembly, as along such interconnecting structures as ductwork or piping.
Flanking path
Resistance to the transmission of sound caused by the inertia and elasticity of the transmitting medium. In general, the heavier and more dense a body, the greater its resistance to sound transmission.
Acoustic mass
An acoustic barrier erected in a plenum
over a partition to reduce sound
transmission between adjoining rooms.
Plenum barrier
A resilient base for mechanical equipment, installed to reduce the transmission of vibration and noise to the supporting structure. Also Called isolation mount.
Vibration insolator
A heavy concrete base for vibrating mechanical equipment, used in conjunctironwith vibration Isolators to increase the mass of the equipment and decrease the potential for vibratory movement.
Inertia block
Any of several construction methods, 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.
Discontinuous construction
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 fibreglass blanket between.
Staggered-stud partition
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 mountaing
A metal channel for the resilient mountings wallboard to studs or joists, used in sound-isolating construction to reduce the transmission of vibrations and noise.
Resilient channel
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.
Resilient clip
