Glossary - Welch Allyn MicroTymp Operating Instructions Manual

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
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.
200 Vea)----the volume of air that
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