High Frequency Audiometry

Thomas Wardzala wardzal9 at mailw.starnetinc.com
Sun Jan 28 01:48:39 EST 1996


As an undergrad, and as a grad, I have looked at and tested high-Hz's. 
Let's just start by saying that no one has been able to do any CONVINCING
research as to standards for equipment, let alone normal ranges.

What do we know?  Well there is:

1.)  The responses are variable by person due to the variable geometry of
the ear canal and the greater possibility of standing waves in the canal
with high Hz's

2.)  Although the theoretical response range is up to 20 kHz, VERY few
people hear tones that high, and those are the areas that are most
sensitive to damage first.

3.)  High Hz thresholds are repeatable intra-subject....repeat thresholds
are well within +/- 5 dB.


What does all this mean about using high Hz's, and who is using them?

Well, what it means is that high Hz audiometry makes sense when you are
looking for signs of cochlear damage due to noise exposure or
ototoxicity.....

In fact, some places are using high-Hz audiometry as part of screening
procedures for patients on dialysis, kemotherapy, or ototoxic meds

I know of one person who is a musical audiologist....he does testing on
musicians and fits them with in-ear monitors....He's done monitors for the
likes of Aerosmith, Clint Black, and Smashing Pumpkins (had to...he's from
Chicago, too).  Part of his pre-fitting work-up is to do high
frequencies...not as a diagnostic but as a comparison.


As for equipment.......Virtual puts out an audiometer that goes into the
high-Hz's.  Koss also puts out a system.  All the earphones are
circumaural, so that adds another problem in calibration....What coupler
do we use (?).....

I ended up using a home-grown computer based audiometer using a DSP output
from a PC through a programmable attenuator.  The earphones I used were
experimental circumaural Seinhausser's, and we used the 3A coupler
(think?!).


Hopefully I've answered some questions about high-Hz testing....any
comments/questions/flames are always welcome (and might even be
appreciated)....I could also give more info about my stuff or my sources
to anyone interested.

-- 
"Noboby with a good car needs to be justified....and I'll tell you why....I've come a long way since I believed in anything, and I've been half-way around the world....where you come from is gone, where you thought you were goin' weren't never there, and where you are ain't no good until you can get away.....Let's hit the fuckin' road."

Tom Wardzala
wardzal9 at mailw.starnetinc.com



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