Otoport OAE+ABR
User Manual for Otoport DP+TE model
13
Introduction
1.4
Types of otoacoustic emissions
Otoacoustic emissions are sounds which can be recorded in the ear canals
of functionally normal ears.
This Otoport can make two types of OAE measurements: Transient Evoked
OAEs (TEOAEs) and Distortion Product OAEs (DPOAEs).
The difference between the measurements is largely in the means used
to generate and measure the emission, rather than in the source of the
emission itself.
TEOAEs use a click to briefly stimulate the cochlea across a wide
frequency range and record the response from the cochlea.
DPOAEs use a pair of pure tones of specific frequencies (f1 and f2) to
stimulate the cochlea and record the distortion generated by the tones
in the cochlea at a third frequency (2f1-f2). Different pairs of f1 an f2
frequencies are used in turn to acquire emissions from different areas
along the length of the cochlea.
The two measurement techniques have different characteristics and so
lend themselves to different uses, for example:
TEOAE are rapidly acquired, sensitive to small hearing losses and
stimulate the cochlea broadly across the frequency range required for
speech and language development. These properties have meant that
TEOAE have been widely used in newborn hearing screening programmes.
DPOAE allow testing at higher frequencies and allow emissions to be
measured in patients with moderate hearing losses. These properties have
lead to their use in recording OAEs in older patients who may have mild
hearing losses.
Other applications may benefit from the use of a combination of both tests
and a range of stimulus levels.