QUESTIONS WITH FULL SOLUTION GRADED
A+
◉ conductive hearing loss. Answer: Hearing loss in which there is an
attenuation of sound received at the inner ear due to a breakdown
or obstruction in the transmission system in the external or middle
ear
◉ consensus standards. Answer: Standards or practices mutually
agreed upon by professional groups
◉ continuous noise. Answer: Noise that lasts longer than 1 second
without interruption. Also called steady state noise
◉ Council for Accreditation in Occupational Hearing Conservation
(CAOHC). Answer: The recognized U.S. authority on training
occupational hearing conservationists, course directors, and
professional supervisors of the audiometric monitoring program
◉ course director (CD). Answer: Certified hearing professional who
conducts courses under the Council for Accreditation in
Occupational Hearing Conservation
,◉ custom-molded earplugs. Answer: Earplugs made to fit a specific
individual's ear
◉ C-weighting. Answer: A weighted network or setting on a sound
level meter that employs an electronic filter to measure, in dBC, the
decibel level in the range of frequencies that include low-frequency
sounds and slightly more of the high-frequency sounds than the A-
weighting filter
◉ cycles per second (cps). Answer: Number of sound waves per
second (frequency). Also called Hertz
◉ daily calibration check. Answer: Procedure done (before starting
audiometry each day) to verify that the audiometer is functioning
and producing outputs that are consistent with those obtained on
the day that the exhaustive calibrations were done
◉ de minimis violation. Answer: Small or unimportant violation
◉ decibel (dB). Answer: A measure of sound intensity. dB is a
logarithm of the ratio of two quantities, therefore the reference scale
must be specified. Decibels measured on the A-weighted scale are
called dB(A); decibels measured using an audiometer referenced to
"Hearing Threshold Level" are dB HL or dB HTL; decibels measured
using a sound level meter are referenced to sound pressure of 20
micropascals are DB sPL
,◉ Department of Defense (DoD). Answer: The U.S. government
department responsible for ensuring national security; includes
Department of the Air Force, Army, Navy, and Marine Corps
◉ de-rating. Answer: Adjusting the noise-reduction rating of a
hearing protection device to estimate actual field attenuation as
opposed to attenuation measured in a laboratory.
◉ diaphragm. Answer: Thin piece of material, typically on the head
of a handheld microphone or in the center of an earphone; vibrates
when either sound waves strike it (microphone) or when electrical
signals cause it to vibrate (earphone). These vibrations are
converted into an electrical current (microphone) or an auditory
signal (earphone)
◉ disposable foam earplug. Answer: Foam earplugs that are thrown
away after use
◉ docket. Answer: A special file devoted to a regulation
◉ dosimetry (noise). Answer: The integrated measure of noise
exposure levels over a period of time
, ◉ dual-hearing protection level. Answer: The noise level at which
concurrent use of an earmuff and an earplug is indicated (e.g., the
mine Safety and Health Administration requires mine operators to
provide dual hearing protection at a time-weighted average of 105
dB(A) or the equivalent dose of 800%)
◉ dual hearing protectors. Answer: Concurrent use of an earmuff
and an earplug to achieve greater noise attenuation. Also called
double protection hearing protectors
◉ duration. Answer: Subjective perception of time
◉ dynamic range. Answer: A range incorporating the lowest to
highest range (e.g., the range over which a noise dosimeter can
accurately measure noise)
◉ ear canal. Answer: Anatomical tube extending from the outer ear
(pinna) to the middle ear (tympanic membrane, or eardrum). Also
called the external auditory meatus
◉ ear canal collapse. Answer: Caused by pressure of the supra-aural
earphones, a narrow ear canal can become fully closed and make
hearing thresholds poorer than the person's actual hearing
sensitivity