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As printed in Hearing Health, volume 19:1,
Spring 2003
By Anne-Marie Liss
I am a happy member of a new breed of hearing health
consumer: a binaural hybrid listener. I use this name
for myself because I hear speech, music and a variety
of environmental sounds with a hearing aid in one ear
and a cochlear implant (CI) in the other. These two
devices send very different kinds of sound signals to
my brain: an acoustic signal from the hearing aid and
an electric signal from the implant. After five years
of careful listening experience, my “biological”
and my “bionic” ears now share the complex
job of helping me to hear and sort out the multitude
of sounds that compete for my attention.
How I Got Here
In 1997, I anxiously placed my fragile hearing health
in the hands of the medical, scientific and biomedical
engineering facilitators of CI technology. As I had
spent so much of my life with hearing aids in both ears,
I was no stranger to the benefits of hearing assistive
devices. Research and technological innovation in the
hearing and speech sciences brought a steady succession
of progressively smaller and more sophisticated hearing
aids to my rescue and kept me actively engaged in all
aspects of life.
After 36 years of using hearing aids, they had become
an extension of my physical, mental and social well-being.
Losing even one of them to occasional factory repairs
or replacements felt like a serious medical emergency.
My bond with hearing aid technology seemed to fall
apart, however, during the mid 1990s when my progressive
hearing loss reached severe-to-profound levels in both
ears. While I still had useful low frequency sound reception
through both hearing aids, the middle and higher frequencies
that are critical to much of everyday speech communication
were no longer “aidable” or amplifiable.
The audiogram of my speech reception thresholds seemed
to tell a dire story but other tests were less grim.
Despite greatly diminished residual hearing and minimal
benefit from amplification, I and my two hearing aids
were still performing quite well with understanding
sentences and paragraphs in quiet settings. Although
I could not grasp individual words (scoring a mere eight
percent on the single word list), I could still grasp
a large number of everyday sentences (scoring 64 percent
on the sentence test).
These strangely contradictory measurements almost
disqualified me as a candidate for a CI. Fortunately
for me, the candidacy evaluation team decided to take
a chance on me as a “borderline case.”
Once medically approved, I was eager to move forward
but was not sure I would be ready to listen with a single
ear. Although the hearing aid in my other ear was still
providing the same low frequency speech, music and environmental
sounds as the one in my soon-to-be implanted ear, the
CI team did not think that this information would help
me much once I started listening with the my implant.
In fact, there was concern that this information (an
acoustic sound signal) might conflict with the new electrically
coded sound signal from my implanted ear. I was encouraged
to focus on my “new ear” and to let my “old
ear” (and my residual hearing) gradually find
its way into retirement.
Despite serious misgivings, I decided to make the
best use I could of the sound information from my single
implanted ear. Thankfully, that information started
arriving immediately after my CI was activated and,
despite its dramatic strangeness, it was immediately
useful. Speech sounds and many important environmental
sounds that had become distant memories were quickly
returning to my awareness.
During this early stage of my implant adaptation, the
dreaded “tradeoff” between my old and new
hearing did not seem as large as I thought it might
be. I was so busy listening to new sounds that I didn’t
have much time to think about my residual hearing, my
other ear or my remaining hearing aid.
Unexpected Revelations
Once I started to mature as a CI listener and to become
less distracted by new sounds, I began to notice that
several other useful sounds were missing. Some of these
were distant environmental sounds like cars, trains
and heavy mechanical equipment. Others were nearer,
low intensity background sounds, such as television
dialogue, music in another room or objects falling several
rooms away. And a few were special and more meaningful
sounds -- the keys on my piano and the sound of my own
voice when I sang. I was puzzled as to why these sounds
that had been just as large a part of my life as speech
were not returning as clearly.
One day, about a month after my CI activation, I decided
to put a hearing aid back on my non-implanted ear. I
sat down again at my piano to play and listen. Almost
immediately, the strange and unpleasant noises I had
been hearing at the piano with my CI alone began to
sound much better and more familiar.
After several more days of listening at the piano,
first with each device alone and then in combination,
I felt a growing sense of excitement. While the music
was not exactly the way I remembered it from before,
it was now almost as pleasant, harmonious and emotionally
stimulating as it was when I first began to study music
many years ago. It was as though my two ears were rediscovering
each other after a brief but sudden and stressful two-month
separation.
Shortly after these discoveries at the piano, I began
to notice other improvements from using my hearing aid
with my CI. Hearing speech in noise and in complex environments
like office buildings filled with echoes, noisy sidewalks
and wide-open spaces was considerably easier.
Quantifying My Experience
When my CI speech evaluation was completed at the University
of Virginia Health System in the spring of 2001, my
own impressions were objectively confirmed: my hearing
aid was contributing significantly to my speech listening
abilities. My test scores in quiet and in noise were
dramatically higher with the two devices together than
with the CI alone. Smiling, my audiologist shrugged
her shoulders and said from that day forward she would
evaluate my hearing with both devices, rather than with
my implant alone, since it was obvious that I was still
a two-ear listener.
Recently, researchers at the Hearing and Speech Research
Laboratory at the University of California, Irvine,
conducted additional tests of my hybrid hearing. They
examined melody recognition in music as well as several
challenging types of speech perception that are not
routinely measured. The results confirmed once again
that I am benefiting from the CI/hearing aid combination.
Coordinated device programming experiments of the
combined signals from my two hearing devices are now
underway. These are designed to discover the best program
settings for each instrument so that my overall listening
performance can be improved further. Test results will
help clinical audiologists to more effectively program
other binaural hybrid listeners as well as future implant
candidates who may be able to benefit from this promising
new hearing health option.
Coming Full Circle
My surprising adventures as a CI listener have highlighted
and reaffirmed my origins as a biological listener.
Time and again, during my challenging journey back into
healthy hearing, I have relied upon my earliest auditory
experiences to guide me as a pioneer binaural hybrid
listener. I am grateful to be living in an age where
it is possible, even with a severe-to-profound hearing
loss, to not only preserve but also to significantly
enhance our sense of hearing.
Anne-Marie Liss, a research consultant, worked for
over 16 years as a regulatory and legislative specialist
for major telecom companies, law firms and foreign government
agencies. She lives in Arlington, Va., and may be contacted
by e-mail at amliss@bellatlantic.net.
Related article:
Are Two Ears
Better Than One?
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