Adults with severe hearing loss benefit from pairing a cochlear implant in one ear with a hearing aid in the other ear, even though the sound signals from each device are very different, according to a study at Washington University School of Medicine published in the Journal of the American Academy of Audiology.
The patients were better able to hear spoken words and to locate the direction of a sound with both devices turned on compared with either device alone. Additionally, the patients liked the fuller, richer sound they heard when using both devices.
Each of the 19 study participants received a cochlear implant in one ear and a hearing aid for the other ear. Because the participants were profoundly hearing impaired, the hearing aid restored only partial hearing in one ear, while the cochlear implant gave them a greater level of hearing in the other ear. Specialists have questioned whether patients could adequately integrate the asymmetric signals from implants and hearing aids.
This study showed that when the participants used both a cochlear implant and a hearing aid, speech recognition improved by an average of 14 percent over when they used just an implant or just a hearing aid. When both devices were active, participants also made fewer mistakes in determining sound direction.
“Even when patients have minimal hearing with a hearing aid, it still helps them get input and helps them catch important sound cues,” says lead author Lisa Potts, PhD, research instructor in otolaryngology. “The two inputs are complementing each other. Hearing aids are better at giving temporal speech cues, while implants supply a fuller spectrum of sound frequencies.”
The researchers are now studying whether a second cochlear implant gives additional benefit over that of an implant plus hearing aid in some of the same patients who participated in this study. But Potts indicates that for some adults with profound deafness, a single implant with a hearing aid may be the best solution due to cost and risks.
Potts LG, et al. Recognition and localization of speech by adult cochlear implant recipients wearing a digital hearing aid in the nonimplanted ear (bimodal hearing). Journal of the American Academy of Audiology. 20(6):353-73, 2009.