Abstract
The inner hair cells (IHCs) are the transducers of the cochlea; they convert mechanical
vibrations to neural activity. When the IHCs and/or neurons are nonfunctioning over
a certain region of the cochlea, this is referred to as a dead region. A dead region
can be defined in terms of the characteristic frequencies of the IHCs and/or neurons
immediately adjacent to the dead region. Dead regions can be detected, and their limits
can be determined, using the threshold equalizing noise (TEN) test or by measurement
of psychophysical tuning curves (PTCs). Both PTCs and the TEN test can be used to
assess children as young as 7 years of age. The identification of dead regions can
be helpful in determining the appropriate form of amplification. For both adults and
children with restricted dead regions (“holes”), benefit is obtained from amplification
of frequencies up to at least 4 kHz. For adults and children with extensive continuous
dead regions starting at a relatively low frequency (≤ 1.5 kHz) there may be little
or no benefit from amplification of high frequencies.
Keywords
dead region - TEN test - psychophysical tuning curve - amplification - hearing aid
