By: Jace Wolfe, PhD
Over the past several years, there have been numerous advances in cochlear implant technology and services. As recent as a decade ago, there were little to no technological solutions available to assist a cochlear implant candidate/recipient, who presented with severe to profound hearing loss, with speech recognition in difficult listening situations—understanding speech in noisy and reverberant settings, over the telephone or television, and when spoken from a distance. Today, cochlear implant manufacturers offer a wide variety of solutions to meet the needs of patients with hearing aids or cochlear implant processors who struggle to communicate. This article identifies ten ways in which cochlear implant technology and services have evolved and improved in the past few years.
10. Automatic scene classification: Hearing aids have featured acoustic scene classifiers for almost a decade. Through these systems, hearing aids classify an environment as one that possesses background noise, speech in quiet or in noise, music, wind, and so forth. Once the listening situation is classified into one of these environments, the hearing aid selects the appropriate form of signal processing that will theoretically optimize performance in the given environment. This technology can be quite valuable as many users are unlikely to manually switch to programs designed for specific, challenging situations. Furthermore, this system will likely be well-received by cochlear implant users as it makes its way to implant sound processors.
9. The development of new speech recognition materials that provide a more realistic assessment of how hearing aid and implant users perform in real-life listening situations: Cochlear implant technology has improved so much that many users score near 100% correct on sentence recognition tests in a quiet environment with a single talker who is male and speaks at a slow to moderate rate. Additionally, many hearing aid users who struggle substantially in realistic situations also often score too well on these tests to meet the indications for cochlear implant candidacy. This fact makes it difficult to distinguish between excellent implant and hearing aid users and good users who may benefit from additional services.
Recently, new measures have been developed to provide a more realistic indication of how persons with hearing loss understand speech in the real world. These measures may include multiple talkers (e.g., two men and two women) who speak at rates are more similar to what we encounter in daily communication settings or more complex sentence materials. Because of these changes, professionals are now equipped with materials that provide a better representation of the difficulties hearing aid wearers may experience in daily listening situations and can better evaluate cochlear implant candidacy and outcomes. Hearing aid users who struggle with these updated measures are frequently able to qualify for cochlear implantation, as they are less likely to be hindered by ceiling effects.
8. Single-sided deafness: A recent trend in hearing health care is the consideration of cochlear implantation for persons with single-sided deafness. Traditional solutions for this population involve capturing the signal of interest at the side of the poor ear and transferring it to the better ear. This approach overcomes the head shadow effect, but it provides limited to no improvement in localization or in speech recognition in noise. In contrast, cochlear implantation in the poor ear can partially re-establish binaural hearing, which may improve access to sounds originating from the side of the poorer ear, localization, as well as speech recognition in noise. Furthermore, cochlear implantation of the poorer ear may provide relief from debilitating tinnitus.
7. A trend toward the provision of bilateral cochlear implant use or bimodal use (a hearing aid on one ear and a cochlear implant on the other ear): Over the past decade, there has been a definitive trend toward the provision of bilateral cochlear implantation for patients with bilateral, severe to profound hearing loss. For patients who do not pursue bilateral cochlear implantation, a hearing aid should be used on the ear opposite the cochlear implant. Bilateral cochlear implant use and bimodal use have been shown to improve outcomes over unilateral cochlear implant use. All patients with bilateral hearing loss should be considered candidates for bilateral hearing technology.
6. Improvements in surgical techniques: A decade ago, many professionals noted (partially in jest) that surgery was the simple part of the cochlear implant process. More attention was placed on the importance of audiology and rehabilitative services in cochlear implant outcomes. We now understand and fully appreciate the critical role of surgery; specifically, it is imperative to ensure the proper insertion of the implant electrode array into the scala tympani of the cochlea and to facilitate an atraumatic insertion in the process. New developments in surgical techniques and electrode array design have most certainly led to better outcomes for cochlear implant recipients.
5. Dual microphone directional technology: Directional microphone technology is one of the most effective means to improve speech recognition in the situation in which implant users struggle the most, listening in noise. Sophisticated adaptive beamforming directional systems are commonplace in contemporary hearing aid technology and over the past several years, cochlear implant manufacturers have incorporated dual microphone beamforming into their cochlear implant sound processors. As of the past month, all cochlear implant manufacturers offer a sound processor with directional microphone technology.
4. Signal processing to improve speech understanding in noise: Cochlear implant manufacturers have developed numerous signal processing algorithms designed to improve performance in noise. Many recipients are able to understand speech better in noise with the use of these technologies and report better listening comfort in noise.
3. A trend toward the use of wireless hearing assistance technology with cochlear implant sound processors: Despite the inclusion of directional technology and signal processing to improve cochlear implant performance in noise, many cochlear implant users continue to struggle with communication in background noise. Additionally, many cochlear implant users report difficulty understanding speech over the telephone and television. Implant manufacturers have developed wireless hearing assistance technology that can stream a signal of interest via digital radio transmission from a remote microphone, a Bluetooth-enabled mobile telephone, or a television to the user’s sound processor. These hearing assistance technologies should be considered by all cochlear implant recipients for routine use.
2. A trend toward providing cochlear implantation at earlier ages for children who are born with hearing loss: Hearing health care professionals have long understood the importance of early intervention for children who have hearing loss. Historically, children born with severe to profound hearing loss receive a cochlear implant between their first and second birthdays. Over the past few years, however, cochlear implantation has been provided to infants younger than one year of age. It certainly appears as though outcomes for earlier implanted children may be better than outcomes for children implanted at one year of age or later. In cases of congenital severe to profound deafness, clinicians should strive to limit the period of time over which the child is deprived of consistent access to intelligible speech.
1. Electroacoustic stimulation: As cochlear implant electrode arrays and surgical techniques have evolved, the potential to preserve residual hearing has greatly improved. For persons who have significant residual hearing in the low-frequency range with severe to profound high-frequency hearing loss, the ideal scenario is to provide acoustic stimulation by way of hearing aid amplification in the low frequencies and electrical stimulation by way of cochlear implantation in the high frequencies. Hybrid cochlear implant systems feature shorter electrode arrays designed to facilitate hearing preservation and also feature sound processors capable of providing low-frequency acoustic amplification and high-frequency electrical stimulation. Many patients with precipitously sloping hearing loss have benefitted significantly from electroacoustic stimulation. This technology provides the hearing health care professional with another tool to serve patients who typically struggle with hearing aids and formerly did not qualify for conventional cochlear implant technology.
These advances in cochlear implant technology and services are capable of improving the lives of persons with severe to profound hearing loss. However, it is important to note, the cochlear implant technology must be programmed appropriately to meet the unique needs of each implant recipient, allowing the recipient to reach his or her full potential. Optimal cochlear implant outcomes are dependent upon the programming audiologist’s ability to customize sound processor settings for each individual user. The new book, Programming Cochlear Implants, Second Edition by Jace Wolfe, PhD, and Erin C. Schafer, PhD, was developed as a guide for professionals who program cochlear implants. It is an excellent resource for professionals seeking to optimize outcomes for cochlear implant users.
About the Author
Jace Wolfe, PhD, is the director of audiology at the Hearts for Hearing Foundation. He is an adjunct assistant professor in the Audiology Department at the University of Oklahoma Health Sciences Center and Salus University. He is also a co-editor for Plural Publishings Core Clinical Concept Series on cochlear implants. Dr. Wolfe is a member of the Better Hearing Institutes Pediatric Advisory Board as well as the Audiology Advisory Boards for Cochlear Americas, Advanced Bionics, and the Phonak Hearing Aid Company. He serves on the editorial board and co-authors a column, Tot Ten, for The Hearing Journal and is also a reviewer for several peer-reviewed journals. He has published numerous articles and is the co-author of Programming Cochlear Implants. Dr. Wolfe provides clinical services for children and adults with hearing loss. His areas of interests include pediatric amplification and cochlear implantation, personal FM systems, and signal processing for children.