oae systems

Michael Gorga GORGA at BoysTown.ORG
Mon Mar 10 11:17:02 EST 1997


Recently someone posted a request for information about specific
OAE systems, presumably because of an interest in buying one.  I
have stayed away from these discussions, because I do not want to
be viewed as ever endorsing (or condemning) any device.  However,
a number of people have posted endorsements of certain devices in
general, nonspecific terms.  I still will not endorse any piece
of equipment, but I will suggest somethings to consider when
purchasing a device.

1.  Does it measure the OAE you wish to measure?

2.  How flexible is the device in relation to your needs?  Are
you forced into doing only what is specified by the manufacturer
or do you have the option to create your own stimulus and
response conditions.

3.  Here's a biggie.  What are the levels of distortion produced
by the recording system.  No device is linear ad infinitum.  At
what levels does the system produce distortion?  These numbers
are important because they describe the limits of the
measurement.  Statements such as "distortion was below the noise
floor" are only informative if the actual noise floor during the
measurement is stated.

4.  Another issue (related to #3 above) is how the signal is
delivered to the ear.  It generally is wise to keep the distance
between the transducers and the output of the probe as short as
possible in order to avoid acoustical problems (for example,
standing waves).

5.  How difficult will it be to operate the device?  Stated
differently, is it user friendly?  I place this question lower on
my list because I am more interested in the response properties
of the instrument than I am in how easy it is to use.  If a
device is very user friendly but produces unreliable or invalid
data, then it is useless.

If I were considering a purchase, I would ask these questions and
compare devices according to the answers.  My decision would be
based on the responses, taking into account that each question
does not have equal weight.

Michael Gorga



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