Hearing Aid Dispenser Written Exam
UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS
Db loss of a perforation of TM - CORRECT ANSWER 10-15db loss
Procedure done to fix perforation - CORRECT ANSWER tympanoplasty or myringoplasty
Monomeric spots - CORRECT ANSWER looks like a hole in TM, but reflects light like a
mirror. Holes that have healed. Aka "mirror membranes"
Average dimentions of an adult eardrum - CORRECT ANSWER 2.3-2.9cm in length, .7cm in
diameters
Pars tensa - CORRECT ANSWER lower 4/5 of TM and tight
Pars flaccida - CORRECT ANSWER upper 1/5 of TM and flaccid
Otis externa - CORRECT ANSWER "swimmers ear" - inflammation of the walls of the EAM.
Will not cause loss unless swelling blocks canal. Treat: warm salt water, drying it, topical antibiotics
Polyps - CORRECT ANSWER masses of tissue that grow outward from a surface
Cholesteatoma - CORRECT ANSWER non-cancerous tumor in the middle ear. Oderous
discharge. Sometimes perforates upper TM. Invasions of skin into the middle ear - sac of concentric
rings of protein. Causes conductive loss. Most dangerous pathology.
Enlarged canal - CORRECT ANSWER result of ear surgery. Often have no ear drum or
ossicular chain. Need approval of physician before fitting
Tympanosclerosis - CORRECT ANSWER white, chalky calcium deposits caused by
degeneration of tissue on eardrum, thicking and scarring from peforations and infections
,Epitympanic cavity - CORRECT ANSWER attic of middle ear. Allows air into mastoid cells of
temporal bone. Branches several nerves
Incudotapedial junction - CORRECT ANSWER top of incus to head of stapes
Annular ligament - CORRECT ANSWER footplate of stapes that is held in the oval window
Speed of sound - CORRECT ANSWER 700mph or 340 m/s (4x as fast through water, 14x as
fast through steel)
Reflection - CORRECT ANSWER is an echo or a reverberation
Reverberation - CORRECT ANSWER often in a small room, 17m or less, reverbs can mask
high frequencies
Echo - CORRECT ANSWER heard and perceived later than original sound (more than 1/10s
after)
Absorption - CORRECT ANSWER aborbs sound. Can improve environments w/ reflection or
reverb. Better in warmth and moist
Diffraction - CORRECT ANSWER sharpness in the change in direction of sound, bending.
High diffraction=bigger wavelengths (low freq)
Refraction - CORRECT ANSWER sound passes through one medium to another, change in
speed and wavelength
Infrasound - CORRECT ANSWER below audible range of 20 Hz
Ultrasound - CORRECT ANSWER above audible range of 20K Hz
, Octave - CORRECT ANSWER anytime the frequency doubles. F(2) = on octave; f(3)= two
octaves
Faintest sound a human can hear - CORRECT ANSWER 10 ^ -16 watts/cm^2 and pressure of
.0002 dynes/cm^2
Threshold of pain - CORRECT ANSWER 1000 dynes/cm^2
When SPL levels double how many db levels increase? - CORRECT ANSWER 6 db
Db HL expresses: - CORRECT ANSWER threshold levels
Db SPL expresses: - CORRECT ANSWER voices or environmental sounds
Pinna function: - CORRECT ANSWER gather sound, aid in localization, enahnce high freq bw
2k-5k hz
Aperture - CORRECT ANSWER entrance to canal, first bend
Isthmus - CORRECT ANSWER narrowing of canal
Resonance frequency - CORRECT ANSWER between 3k-4k (or 2k-5k in other studies) range,
natural boost of 10db, when combined w/ high freq enhancement of the pinna - 15-20 db increase
around 2700 hz
Stenosis - CORRECT ANSWER narrowing of ear canal
Atresia - CORRECT ANSWER absense of an ear canal
Microtia - CORRECT ANSWER smaller than normal pinna
UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS
Db loss of a perforation of TM - CORRECT ANSWER 10-15db loss
Procedure done to fix perforation - CORRECT ANSWER tympanoplasty or myringoplasty
Monomeric spots - CORRECT ANSWER looks like a hole in TM, but reflects light like a
mirror. Holes that have healed. Aka "mirror membranes"
Average dimentions of an adult eardrum - CORRECT ANSWER 2.3-2.9cm in length, .7cm in
diameters
Pars tensa - CORRECT ANSWER lower 4/5 of TM and tight
Pars flaccida - CORRECT ANSWER upper 1/5 of TM and flaccid
Otis externa - CORRECT ANSWER "swimmers ear" - inflammation of the walls of the EAM.
Will not cause loss unless swelling blocks canal. Treat: warm salt water, drying it, topical antibiotics
Polyps - CORRECT ANSWER masses of tissue that grow outward from a surface
Cholesteatoma - CORRECT ANSWER non-cancerous tumor in the middle ear. Oderous
discharge. Sometimes perforates upper TM. Invasions of skin into the middle ear - sac of concentric
rings of protein. Causes conductive loss. Most dangerous pathology.
Enlarged canal - CORRECT ANSWER result of ear surgery. Often have no ear drum or
ossicular chain. Need approval of physician before fitting
Tympanosclerosis - CORRECT ANSWER white, chalky calcium deposits caused by
degeneration of tissue on eardrum, thicking and scarring from peforations and infections
,Epitympanic cavity - CORRECT ANSWER attic of middle ear. Allows air into mastoid cells of
temporal bone. Branches several nerves
Incudotapedial junction - CORRECT ANSWER top of incus to head of stapes
Annular ligament - CORRECT ANSWER footplate of stapes that is held in the oval window
Speed of sound - CORRECT ANSWER 700mph or 340 m/s (4x as fast through water, 14x as
fast through steel)
Reflection - CORRECT ANSWER is an echo or a reverberation
Reverberation - CORRECT ANSWER often in a small room, 17m or less, reverbs can mask
high frequencies
Echo - CORRECT ANSWER heard and perceived later than original sound (more than 1/10s
after)
Absorption - CORRECT ANSWER aborbs sound. Can improve environments w/ reflection or
reverb. Better in warmth and moist
Diffraction - CORRECT ANSWER sharpness in the change in direction of sound, bending.
High diffraction=bigger wavelengths (low freq)
Refraction - CORRECT ANSWER sound passes through one medium to another, change in
speed and wavelength
Infrasound - CORRECT ANSWER below audible range of 20 Hz
Ultrasound - CORRECT ANSWER above audible range of 20K Hz
, Octave - CORRECT ANSWER anytime the frequency doubles. F(2) = on octave; f(3)= two
octaves
Faintest sound a human can hear - CORRECT ANSWER 10 ^ -16 watts/cm^2 and pressure of
.0002 dynes/cm^2
Threshold of pain - CORRECT ANSWER 1000 dynes/cm^2
When SPL levels double how many db levels increase? - CORRECT ANSWER 6 db
Db HL expresses: - CORRECT ANSWER threshold levels
Db SPL expresses: - CORRECT ANSWER voices or environmental sounds
Pinna function: - CORRECT ANSWER gather sound, aid in localization, enahnce high freq bw
2k-5k hz
Aperture - CORRECT ANSWER entrance to canal, first bend
Isthmus - CORRECT ANSWER narrowing of canal
Resonance frequency - CORRECT ANSWER between 3k-4k (or 2k-5k in other studies) range,
natural boost of 10db, when combined w/ high freq enhancement of the pinna - 15-20 db increase
around 2700 hz
Stenosis - CORRECT ANSWER narrowing of ear canal
Atresia - CORRECT ANSWER absense of an ear canal
Microtia - CORRECT ANSWER smaller than normal pinna
