Hearing impaired individuals with severe to profound
hearing loss and poor speech understanding who possess some
residual hearing in one ear may experience significant
communication benefit from a cochlear implant even if it is
placed in the ear with worse hearing, a Johns Hopkins study
There is growing evidence that the amount of hearing
in an ear prior to surgery is unrelated to a patient's
ability to interpret speech using an implant, said Howard
W. Francis, lead author of the study and an associate
otolaryngology head and neck surgery. Therefore, the
better hearing ear could be saved for the continued use of
a hearing aid or future technology to complement a cochlear
implant, Francis said.
Reporting in the August issue of the journal Ear and
Hearing, Francis and colleagues compared patients with no
residual hearing, patients with some residual hearing in
one ear and patients with some residual hearing in both
ears. The patients' ability to interpret sounds and speech
was measured before and after cochlear implant surgery.
Patients with residual hearing in one or both ears
prior to surgery scored significantly higher on the speech
perception tests following surgery, even when the implanted
ear was profoundly deaf prior to surgery. The researchers
also noted that patients' ability to interpret speech in a
noisy environment increased dramatically over time in
proportion with the amount of residual hearing in the
"In cases where even a small amount of hearing ability
remains in one ear, the central nervous system is better
able to integrate auditory information with a cochlear
implant, and equally so from either ear," Francis said.
"This speaks to the brain's circuitry and its ability to
interpret electrical signals generated by the implant even
in the presumably more degenerated ear."