Glossary
acoustic admittance
(Ya)--the
ease with which acoustic energy is
transferred into a system; the ratio of volume velocity to sound
pressure.
acoustic millimho
(mmho)--the
unit of acoustic admittance;
1 mmho =
10’*m3/pa
s.
aural acoustic immittance-a
term used to refer to aural acoustic
admittance, acoustic impedance, or any of their components.
cholesteatoma-see
keratoma.
dekapascal (daPa)--the
unit of air pressure used for tympanometric
measurements. 1
daPa
= 1.04 mm H20.
equivalent ear canal volume
(+
200
Vea)----the
volume of air that
has the same acoustic admittance as the ear canal/middle ear
system when the ear is pressurized. The
MicroTymp
measures
Vea with a
226-Hz
probe tone and an ear canal air pressure of
t-200
daPa.
Under these conditions, Vea is a good estimate of
the volume of air in front of the probe. Vea is abnormally large in
some patients with ear drum perforations and patent
tympano-
stomy tubes.
keratoma-a
collection of keratinizing squamous epithelium that
invades the middle ear; it frequently originates from a perforation
in Shrapnell’s membrane (pars flaccida) of the tympanic mem-
brane; also called cholesteatoma.
lateral ossicular
fixation-fixation of the
malleus
and/or incus,
frequently caused by tympanosclerosis, a complication of chronic
otitis media.
middle ear effusion-an
accumulation of fluid (liquid) in the middle
ear.
neomembrane-a
scar on the tympanic membrane; the scarred
region may be thinner and have a higher admittance than the
normal tympanic membrane.
otitis media with
effusion-inflammation of the middle ear accom-
panied by an accumulation of fluid (liquid).
otosclerosis-a
genetic abnormality of the temporal bone, fre-
quently causing fixation of the stapes and conductive hearing
loss.
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