Document N8VxE39Y9MmXaQG9mbV8z4ow

dividual's threshold from the zero reference of the audiometer High frequency loss Refers to a defi cit starting with 2000 Hz and beyond Intensity level (sound-enercy flux DENSITY LEVEL) In decibels, of sound is 10 times the logarithm to the base 10 of the ratio of the intensity of this sound to the ref erence intensity The reference intensity shall be stated explicitly Interrupter switch Usually called the "presenter switch" because it permits the stimulus to be presented or cut off from the earphones but it leaves the audiometer circuits in operation, making it possible to change the frequency and intensity level of the tone without the listener's knowledge Level The logarithm of the ratio of that quantity to a reference quantity of the same kind The base of the logarithm, the refer ence quantity, and the ktnd of level must be specified LOUDNESS The intensive attribute of an auditory sensation, in terms of which sounds may be ordered on a scale extending from soft to loud Loudness depends primarily upon the sound pressure of the stimulus, but it also depends upon the frequency and wave form of the stimulus Loudness level A sound, m phons, is numerically equal to the median sound pres sure level, in decibels, relative to 0 0002 microbar, of a free progressive wave of fre quency 1000 Hz presented to listeners facing the source, which in a number of trials is judged by the listeners to be equally loud Malingerer One who pretends deaf ness or other abnormalities MASKING The stimulation of one ear of a subject by controlled noise to prevent his hearing with that ear the tone or signal given to the other ear This procedure is used where there is at least 15 to 20 dB difference in the two ears Meniere's disease The combination of deafness, tinnitus, and vertigo Monaural Hearing Refers to hearing with one ear only Narrow band Applies to a narrow band of transmitted waves, with neither of the critical or cutoff frequencies of the filter being zero or infinite Noise Any unwanted sound Noise-induced hearing loss The terminology used to refer to the slowly pro gressive inner ear hearing loss that results from exposure to continuous noise over a long period of time as contrasted to acoustic trauma or physical injury to the ear Noise level For air-bome sound, unless specified to the contrary, noise level is the weighted sound pressure level called sound level, the weighting must be indicated Noise reduction A decrease of the sound pressure level at a specified observa tion point, which is attributable to a desig nated structure Noise reduction is also used to designate the differences in sound pres sure levels existing at two different locations at a single time, when the designated struc tures are in posibon The term noise control is meaningful only when noise control com ponents and the points of observation are fully specified Nonauditory effects of noise Re fers to stress, fatigue, health, work efficiency, and performance effects of loud noise that is continuous Octave The interval between two sounds having a basic frequency ratio of two Octave band An arbitrary spread of fre quencies Organ OF Corti An aggregation of nerve cells lying on the basilar membrane that picks up vibrations and converts them to electrical energy, which is sent to the brain and interpreted as sound It is the "heart" of the hearing mechanism Oscillation The variation, usually with time, of the magnitude of a quantity with respect to a specified reference when the magnitude is alternately greater and smaller than the reference Ossicle A small bone, any member of a chain of three bones from the outer mem brane of the tympanum (eardrum) to the mem brane covering the oval window of the inner ear 1519