BUILDING UTILITIES 3: LIGHTING AND ACOUSTICS EXAM QUESTIONS AND ANSWERS

BUILDING UTILITIES 3: LIGHTING AND ACOUSTICS EXAM QUESTIONS AND ANSWERS SOUND - answerSensation stimulated in the organs of hearing by mechanical radiant energy transmitted as longitudinal pressure waves through the air or other medium. SOUND WAVES - answerA longitudinal pressure wave in air or an elastic medium ,esp. one producing an audible sensation. WAVE - answera 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. WAVEFORM - answerA graphic representation of the shape of a wave, obtained by plotting deviation at a fixed point versus time. WAVELENGTH - answerThe distance, measured in the direction of the propagation of a wave, from any one point to the next point of corresponding phase. PHASE - answerA particular point or stage in a periodic cycle or process AMPLITUDE - answerThe maximum deviation of a wave or alternating current from its average value FREQUENCY - answerThe number of cycles per unit time of a wave oscillation. HERTZ - answerthe SI unit of frequency, equal to one cyce per second. PITCH - answerThe predominant frequency of a sound as perceived by the human ear. WAVE FRONT - answerA surface of a propagating wave composed at any instant of all points having identical phase, usually perpendicular to the direction of propagating. FUNDAMENTAL - answerthe lowest frequency at which a vibrating element or system will freely oscillate. Also called fundamental frequency. HARMONIC - answerA vibration having a frequency that is an integral multiple of that of the fundamental BAND - answerA range of wavelength or frequency between two defined limits OCTAVE - answerThe interval between two frequencies having a ratio of 2:1 DOPPLER EFFECT - answerAn 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 hen they move apart. 1087ft(.3km) per second - answervelocity of sound in air 4500ft(1.4km) per second - answervelocity of sound in water 11,700ft(3.8km) per second - answervelocity of sound in wood 18000ft(5.5km) per second - answervelocity of sound in steel loudness - answera subjective response to sound indicating the magnitude of the auditory sensation produced by the of a sound wave. phon - answera unit for measuring the apparent the loudness of a sound, equal in number to the decibels of a 1000-Hz reference sound judged by a group of listeners to be equal in loudness to the given sound. sone - answera unit for increasing the apparent loudness of a sound judged by a group of listeners to be equal to the loudness of a 1000-Hz reference sound having an intensity of 40 decibels. equal loudness contour - answera curve representing the sound pressure level at which the sounds of the different frequencies are judged by a group of listeners to be equally bond. decibels - answera unit for expressing the relatives 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. hearing - answerthe 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. threshold of pain - answerthe level of sound intensity high enough to produce the sensation of pain in the human ear, usually around 130 dB. auditory fatigue - answerphysical or mental weariness caused bu the prolonged exposure to loud noises. hearing loss - answeran increase in the threshold of the audibility at specific frequencies caused by the normal aging disease, or injury to the hearing organs.