Building Utilities 3 (BU 3) – Acoustics and Lighting Systems PDF

BUILDING UTILITIES 3 (BU 3) – ACOUSTICS AND LIGHTING SYSTEMS ACOUSTIC-RELATED TERMS not understandable, inarticulate. Echoes also cause articulation problems. Articulation is...

BUILDING UTILITIES 3 (BU 3) – ACOUSTICS AND LIGHTING SYSTEMS ACOUSTIC-RELATED TERMS not understandable, inarticulate. Echoes also cause articulation problems. Articulation is most often measured in some form of a desired signal to unwanted noise ratio. ABSORPTION - The loss of sound energy that occurs when the sound wave strikes a fibrous surface. The fibers provide acoustic friction for the sound wave. The wave does ATTENUATION - A reduction in sound level. Sound attenuation in air-conditioning is not slow down due to the friction, it keeps its same speed but it does lose energy and get specified in terms of dB per meter. quieter. AUDIOLOGY - The science and practice of amplifying or otherwise improving how well a ABSORPTION COEFFICIENT - The fraction of the incident sound energy absorbed by a person hears sound. surface. BACKGROUND NOISE - Ambient noise. ACOUSTIC CONSULTANT - Someone, not formally trained, experienced in providing acoustical services. BOOMY - The condition of sound in a room when the lower frequencies, particularly the male voice range are excessively reverberant. ACOUSTIC CONTRACTOR - Someone trained and experienced in installing acoustic tiles and wall panels. BREAK-IN NOISE - Transfer of noise from a space surrounding the duct into the duct through duct walls. ACOUSTIC DESIGNER - Someone, not formally trained, who prepares blueprints for acoustic projects. BREAK-OUT NOISE - Transfer of noise from the interior of a duct through duct walls into a space outside the duct. ACOUSTICAL ENGINEER - One formally educated, experienced in the science and practice of acoustics. BRIGHT/LIVELY - The condition of sound in which there is an abundance of treble range reflections giving the feeling of "brightness" or "liveliness" to the sound. Sound in a tile ACOUSTICIAN - An acoustical engineer who is trained and experienced in voicing bathroom or kitchen is bright. Too much can seem harsh and irritating. rooms. DARK/DEAD - The condition of sound in a room when there is a lack of reflections and a ACOUSTICS - Science which deals with the production, control, transmission, reception lack of reverberance. Too much can seem lack-luster and uneasy feeling. and effects of sound in an enclosed space. DEAD ROOM - A room containing an unusually large amount of sound absorption. ACOUSTICS - The science that studies the waves that are conducted through matter due to the motion of the matter. Usually air is the material that most people think of when DECAY - The dying out of sound. Usually referring to the steady decline in the loudness it comes to acoustic waves. But acoustic waves exist in all matter. Architectural acoustics of the reverberation. is the study of acoustics when the air is contained in a room. Church acoustics is a sub- division of architectural acoustics. DECAY RATE (RT-60) - The time (in seconds) it takes for reverberation to change from very loud to imperceptibly quiet, a total sound level difference of 60 dB. For a living room ANECHOIC CHAMBER - A sealed room in which all the surfaces are designed to the RT-60 might be 1 second but in a gym, it might be 4 seconds. completely absorb all sound produced in the room. DECIBEL (dB) - A unit of measurement for sound pressure level, sound intensity level or ARTICULATION - The clarity of a sound, particularly a message conveyed by sound, sound power level. such that it can be easily and completely understood. A slurred sound may be well heard but the message it carries may still not be well understood, it is inarticulate. Also, a clear DIFFRACTION - A change in the direction of propagation of sound as a result of bending and distinct sound may be drowned out by a nearby louder noise, rendering the message caused by a barrier in the path of a sound wave. Page 1 COLLEGE OF ARCHITECTURE AND SUSTAINABLE BUILT ENVIRONMENT - Pamantasan ng Lungsod ng Maynila Building Utilities 3 : Acoustics and Lighting Systems Compiled by : Arch. Paulo C. PINEDA I BUILDING UTILITIES 3 (BU 3) – ACOUSTICS AND LIGHTING SYSTEMS DIFFUSE SOUND (FIELD) - A sound field in which the sound comes in equal intensity FREQUENCY (Hertz, Hz, cps) - A single sound pulse as from a fire cracker has sound from all directions. energy but no tone. Tones are sounds that come from voices or instruments which have a repetitive pressure pulse characteristic. The number of repeat times per second that a DIFFUSION - Reflections off of a non flat surface that causes the sound wave to become sound has is called it's frequency. It's unit of measurement is cycles per second (cps) more quickly disorganized than if off a flat surface is a diffusive surface. Diffusion also called Hz (Hertz). Similar to pitch in musical terms. decreases the time it takes for echoes to become converted to reverberation. The beautiful gothic churches of the old world have very diffusive or sound scattering FREQUENCY of vibration - The number of complete cycles per second. surfaces. That is part of the sonic beauty of those spaces. IMPACT NOISE - Noise caused by the collision of two objects. DIRECT SOUND - The sound that arrives at a receiver along a direct line from thesource without reflection from any surface. INFRASONIC - A sound that is below the human audible frequency, below 20 Hz. DIRECT SOUND (DIRECT SIGNAL) - The part of a sound wave that travels directly INSULATION - See isolation along the line of sight path between the speaker or sound source and the listener. The dry or actual sound. INTELLIGIBILITY - A measure of the clarity of sound based on the comprehension of the message being conveyed by sound. A "cat, bat, tat, rat... type of recognition test. The EARLY REFLECTIONS - Reflections that are heard within 1/20 of a second of the direct conversational version of Articulation. sound are called early reflections. Early reflections cannot be distinguished from direct signals; they merge with the direct sound to form one composite sound. This combining INTENSITY - Defined as the amount of sound power falling on (or passing through, or effect can cause the sound of the direct signal to change in tonal characteristics and crossing) a unit area. apparent direction. INTERMITTENT SOUND - A sound which is discontinuous or fluctuates to such an ECHO - A sound that has been reflected with sufficient time delay. extent that at times its sound pressure level falls below a measurable level. ENVIRONMENTAL NOISE - Exterior background noise in a neighborhood (ie. traffic, INVERSE SQUARE LAW - A law which states that the sound intensity in a free field aircraft). varies inversely with the square of the distance from the source. FIDELITY - Faithful reproduction of a sound source. ISOLATION - A lack of acoustical connection. FLUTTER ECHO - A rapid but repetitive succession of sound from a sound source LATE REFLECTIONS (ECHOES) - A distinct reflection that arrives at the listener later usually occurring as a result of multiple reflections in a space with hard, flat and parallel than 1/20th of a second after the direct sound is heard. The listener can identify from walls. where an echo comes. An echo does not change the tonal characteristics of the direct sound. FLUTTER ECHO - This type of echo is most easily heard as one claps their hands out in front of them, while standing in a hallway. The sound "zings" and its tone depends on LEAK - A small opening in a barrier that allows airborne sound to pass through. how many times a second the reflection passes by the listener's head. In a hall 8' wide, the clap will expand out, hit the wall and return 143 times a second and the zing will LIVE ROOM - A room containing an unusually small amount of sound absorption. sound like a 143 Hz buzzy tone. Not a real sound, just a pseudo-tone. LOUDNESS - An auditory sensation that depends on sound pressure level and the FREQUENCY - The number of full cycles per second measured. frequency of sound. Page 2 COLLEGE OF ARCHITECTURE AND SUSTAINABLE BUILT ENVIRONMENT - Pamantasan ng Lungsod ng Maynila Building Utilities 3 : Acoustics and Lighting Systems Compiled by : Arch. Paulo C. PINEDA I BUILDING UTILITIES 3 (BU 3) – ACOUSTICS AND LIGHTING SYSTEMS LOUDNESS - The apparent strength of the sound to the listener. A change in 1 dB is just PSYCHOACOUSTICS - The study and science of how the human comprehends and barely noticed as a change in loudness. Something twice as loud is actually 10 dB makes sense out of the sounds they hear. The difference between an early reflection and stronger, (10 times stronger). Something half as loud is 10 dB weaker, (1/10th as strong). a late (echo) reflection, is an example of psychoacoustics. The blending of the early reflections with the direct sound is another. MASKING - The increase in the threshold of audibility of a sound that is required so that the sound can be heard in the presence of another sound. REFLECTION COEFFICIENT - A measure of the sound reflective property of a surface. NOISE (BACKGROUND NOISE) - The unwanted, undesirable and usually interfering REFLECTIONS - Sound waves that strike a surface and bounce off are reflected sounds. sounds present in a listening space, typically due to an air conditioner or other They bounce off the wall, changing directions but keeping the same angle off the wall as conversations. they had when they approached the wall. NOISE FLOOR - The strength of the background noise, measured in dB. It is difficult to RESONANCE - The relatively large amplitude of vibration produced when the frequency understand what is being said in a room with a high noise floor. of the source of sound is equal to the natural frequency of a room. NOISE ISOLATION CLASS (NIC) - A single number rating derived from the measured REVERBERANT SOUND FIELD - A sound field created by repeated reflections of sound value of noise reduction between two rooms. from the boundaries in an enclosed space. NOISE REDUCTION (NR) - The reduction in sound pressure level of noise. REVERBERATION - For sound in a large room, reverberation begins at about 1/5 second following the direct sound. It is due to the accumulation of many reflections, NOISE REDUCTION COEFFICIENT (NRC) - A single number rating derived from compounding one upon the other, so much that the sound no longer seems composed of measured values of sound absorption coefficients of a material at 250, 500, 1000 and echoes but rather just a sound of noise, a din of chaos that has no discrete direction and 2000 Hz. no discrete timing. NRC RATING - (Noise Reduction Coefficient) A rating for absorption. It gives the % REVERBERATION - The continuation of sound in an enclosed space after the initial efficiency for a surface to absorb sound. If a surface is 30% absorptive, then only 70% of source has been terminated. the incident sound is reflected back into the room. REVERBERATION TIME (RT) - The time it takes for sound intensity to decay by 1 OCTAVE - Sound that exists within a limited frequency range, between a lower set millionth of its steady state value after the sound source has been terminated. frequency and a set upper frequency. The difference between the lower and upper frequency is specified to be equal to the lower frequency. The octave sequence for the SABIN - A unit of measure of sound absorption. note "C" starts at 31 Hz and continues thru 63 Hz, 125 Hz, 250 Hz, 500 Hz, 1k Hz, 2k Hz, 4k Hz, 8k Hz and ends at 16k Hz. (k = thousand). SCATTERING - An irregular diffraction of sound in many directions OUTDOOR-INDOOR TRANSMISSION CLASS (OITC) - A weighted single number SIGNAL-TO-NOISE RATIO (S/N RATIO) - The difference in sound level (dB) between rating of the sound reduction effectiveness of a partition that separates an indoor space the desired sound and the noise floor. from the outside. SONIC COLOR - The shift in emphasis of a complex sound within it's spectral range. A PITCH - A listener’s perception of the frequency of a pure tone. neutral color is the preferred natural sound but sometimes sound can have a warm color, an emphasis on lower frequencies or a cold color, an emphasis on higher frequencies or a nasal color, an emphasis on midrange frequencies. Page 3 COLLEGE OF ARCHITECTURE AND SUSTAINABLE BUILT ENVIRONMENT - Pamantasan ng Lungsod ng Maynila Building Utilities 3 : Acoustics and Lighting Systems Compiled by : Arch. Paulo C. PINEDA I BUILDING UTILITIES 3 (BU 3) – ACOUSTICS AND LIGHTING SYSTEMS SOUND (WAVES) - Pressure fluctuations in the air that are heard when an acoustic wave passes by. They are usually caused by objects in the air that quickly change STRUCTURE-BORNE SOUND - Sound propagated through a solid structure. position or a stream of air that quickly changes position. Sound escapes away from the sound source as an expanding spherical wave that travels at the speed of 1130 feet per TRANSMISSION COEFFICIENT - The ratio of transmitted sound energy to incident second, traveling about 1 1/8th of a foot each one thousandths of a second (millisecond). sound energy. SOUND DESIGNER - One who envisions and directs the way sound plays out of a TRANSMISSION LOSS (TL) - The measure of sound insulation of a partition. stage. ULTRASONICS - Sound whose frequency range is above that of human hearing, above SOUND ENGINEER - Someone trained in setting up microphones and speakers. 20,000 Hz. SOUND INSULATION - The ability of a barrier to prevent sound from reaching a VOICING - The process of defining the desirable condition of sound in an acoustic receiver. space. It integrates the direct, early and late reflections with the reverberation, including a sense of timing and direction for each into an appropriate and desirable acoustic SOUND INTENSITY (SI) - The average rate of sound energy flow through a unit area in condition for the listener. It combines both the art and science of sound. It requires an a given direction. understanding of the purpose to be served by each acoustic space. As an art form, it recognizes the aesthetic side of sound, the impression that most people prefer to have of SOUND INTENSITY LEVEL (SIL) - A quantity expressed in decibels of airborne sound. each particular type of sound that exists in some particular place. As a science, it is based on psychoacoustics. SOUND LEVEL - The measure of the strength of sound. Units are decibels (dB) and usually measured with a dB meter. The threshold of quiet sound is zero dB and the onset WAVELENGTH - Distance between two adjacent compressions or rarefactions in a of painful sound is 100 dB. Conversations are at 50 dB, whispers at 30 dB and shouting sound wave. is 70 dB. When the sound strength of something doubles, it increases by 3 dB, or halved, it drops by 3 dB. WHITE NOISE - A noise whose energy is uniform over a wide range of frequencies. This is analogous to the term “white light”, which consists of almost equal amount of light of SOUND LOCK - A small space that works as a buffer between a source room and a different wavelength (colors). A white noise sounds hissy receiving room. SOUND PRESSURE - Fluctuating pressure of sound superimposed on the static air pressure. SOUND PRESSURE LEVEL - See sound intensity level SOUND SPECTRUM - The sound level measured at different frequencies. Most tones are composed of more than one frequency, a combination of frequencies, as in a musical chord. The sound spectrum would measure the strength of each frequency and display that graph as a plot of Sound Level vs. Frequency, also known as a sound spectrum. The "color" of sound is used as emphasis in the spectrum. SOUND TRANSMISSION CLASS (STC) - A single number rating of the sound insulation rating of a partition. Page 4 COLLEGE OF ARCHITECTURE AND SUSTAINABLE BUILT ENVIRONMENT - Pamantasan ng Lungsod ng Maynila Building Utilities 3 : Acoustics and Lighting Systems Compiled by : Arch. Paulo C. PINEDA I