During the past decade, more adults with one ear having functional hearing have received a cochlear implant.  There is no formal definition for "functional hearing." Given expanded candidacy criteria to include those with asymmetric hearing loss, there are now CI recipients who can understand speech without lip-reading to some degree—especially in quiet conditions. They may also enjoy listening to music and carry out simple phone calls using their hearing aid in their non-implanted ear. 

Guidance given to new CI recipients who have this type of hearing loss is often to: (1) use the CI for the maximum amount of time each day and (2) practice hearing only through the CI without using the hearing aid in the other ear for portions of the day.

Many adults who have at least some significant functional hearing in their non-implanted ear have difficulty fulfilling the second task; giving up their hearing aid, even for a short period of time seems overly difficult. They may expect that the auditory learning process through their CI will occur regardless.

Many people who have functional hearing in their non-implanted ear experience spontaneous auditory learning via their CI, but others need to work towards it intentionally. The information provided from the CI is different, it might be confusing initially but recipients still need to become accustomed to the new sound and learn to interpret it as a meaningful signal. CI recipients tend to rely on the ear that provides them with the most meaningful information. When there is a relatively functional hearing in the non-implanted ear there is a risk that people might unintentionally ignore the information provided to them by their CI.

I see this occasionally in the clinic; people with functional hearing in their non-implanted ear might not efficiently utilize the information provided by the CI, even after one year or more of CI use. They might say that the CI contributes to their sense of intensity but not so much to their ability to understand speech. Many of them feel that their hearing aid provides them with better sound quality compared to the CI. Sometimes, they do not use the implant for all hours of the day because its contribution to their overall hearing is not clear enough. When I ask them whether they've ever tried to practice listening using their CI only, they often say they did not, since it was too difficult to give up the hearing provided by their HA. For these people the information provided by the CI might remain undeciphered and is in the background of what they perceive through their HA. In the situation described, people only use some of the acoustic information provided to them by their CI. In other words, they are not fulfilling their potential to enjoy it.

How might someone work towards more auditory learning in the CI ear?

• Use your CI regularly—during all waking hours 
  
  
• Develop your hearing skills in CI-only mode. You can start by choosing situations you can handle without hearing through your hearing aid, such as those times in which there are no challenging communication requirements and less pressure on you to not to make mistakes or miss important information.
  
  
• Listen to environmental sounds. You will likely find that your CI provides you with access to sounds that you miss via your hearing aid. Learn to recognize home and outdoor environmental sounds so they become meaningful and not ignored. 
  
  
• Listen to speech through your CI

• The CI allows you access to more speech sounds such “s,” “sh,” and “z.”  
• The CI provides cues that cannot be perceived solely by lip-reading and in many instances, not even by lip-reading with the hearing aid. For example, try to distinguish between the words "phase" and "vase” using lipreading.
• Listen to the differences between voices and try to recognize the voices of family, friends, and colleagues.
• As you become more comfortable with your CI only hearing, you should practice your speech perception and speech understanding skills. If you work with an audiologist or speech-language pathologist), they may be able to refer you to suitable materials to practice at home. If you practice independently, you can use the materials found on the CI companies' websites and other materials that were mentioned in previous posts. 
•  Several times a week (or more!) of self-practice in CI-only mode will make the difference!

What can you expect to happen?

• Your hearing outcomes will improve over time.
  
  
• You will feel more oriented by understanding the sounds around you.
  
  
• You will be able to more efficiently make use of the various programs on your sound processor and take advantage of them in various acoustic environments.
  
  
• You will feel that lipreading is less tiring, and you'll be less affected by the speech intelligibility of others including coping with rapid speakers or those with accents.  
  
  
• You may manage be better able to locate sound sources.
  
  
• If you develop the ability to understand speech without lipreading, you may be able to hold more challenging telephone conversations than those you could have carried out in the past using your hearing aid. Streaming sound to both your hearing aid and CI bilaterally or using assistive listening devices may be helpful.
  
  
• When listening to music, you may find that your CI helps you to understand words in songs.
  
  
• You will be better able to understand speech in noisy situations.
  
  
• When taking off your CI and using your hearing aid alone, you will feel that your hearing is lacking—not just in terms of volume but also in terms of speech understanding. The CI contribution to your communication and quality of life will be evident. 

In Conclusion

People with usable functional hearing in the non-implanted ear may face a challenging process of getting used to and utilizing the sound provided by the CI.  Effective auditory learning using CI-only mode will result in improved overall hearing and listening skills, the best possible bilateral hearing, and an improved quality of life.