Today, bilateral cochlear implantation is a common practice; however, it is not always an option for unilateral cochlear implant recipients due to insurance restrictions, personal preference, or significant residual hearing in the non-implanted ear. A successful treatment option for these patients is to combine electric hearing through the use of the cochlear implant, with amplification from a traditional hearing aid in the other ear. Amplification with a hearing aid has shown to be beneficial even when the ear that is amplified with a hearing aid has little to no open-set speech understanding by itself. Combining the electric and acoustic signal may provide the highest level of speech understanding and sound quality.
Research has shown that the benefit provided by acoustic hearing in a non-implanted ear can vary substantially across individuals. Scores on speech understanding can be improved when both a cochlear implant and hearing aid are used together compared to the use of a cochlear implant or hearing aid alone. In fact, some patients can receive significant benefit with the addition of a hearing aid, with single-word recognition improving by 15-20%, and sentence recognition in background noise improving by as much as 20-30% (Dorman et al., 2007; Gifford et al., 2007; Zhang et al., 2012). Even when hearing levels of the non-implanted ear are in the profound range, it is possible to improve speech understanding through the use of a hearing aid combined with the cochlear implant signal.
In addition to improving speech understanding, the use of a hearing aid and cochlear implant together, rather than using one alone, can help an individual feel “balanced” between the two ears. Using two ears for hearing is termed “binaural” hearing. Binaural hearing has been shown to improve one’s ability to locate the source of a sound as opposed to using one ear alone. When two ears are working together they are better able to determine the location of sound by comparing the arrival time of sound at the two ears. Communication between the two ears is possible with the use of a hearing aid and cochlear implant, as evidence shows that using a cochlear implant and hearing aid together can help improve the ability to locate a sound (Ching et al., 2007; Dunn et al., 2005).
While a cochlear implant is successful at conveying speech, it is not especially efficient at portraying fine-grained spectral and pitch information. A cochlear implant user may report that the sound quality of speech or music does not sound “natural.” Therefore, sound quality can often be enhanced with the addition of a hearing aid to the non-implanted ear. Patients using a hearing aid and a cochlear implant often times report that speech sounds “more natural,” “richer,” or “fuller.” Likewise, in a music appreciation study by Kong et al. (2005), melody recognition was enhanced by using a hearing aid in the ear opposite to a cochlear implant.
Finally, the human body functions best when it is being used. Just like the muscles in our body, the auditory system functions on a “use it or lose it” basis. The use of a hearing aid in a non-implanted ear will allow the auditory pathways to remain stimulated. In cases of progressive hearing loss, the use of a hearing aid will provide continued stimulation to an ear that may eventually require a cochlear implant. If you have any questions regarding your hearing or amplification devices, please contact an audiologist.