The objectives of this study were to assess the effectiveness of various measures of speech understanding in distinguishing performance differences between adult bimodal and bilateral cochlear implant (CI) recipients and to provide a preliminary evidence-based tool guiding clinical decisions regarding bilateral CI candidacy.
This study used a multiple-baseline, cross-sectional design investigating speech recognition performance for 85 experienced adult CI recipients (49 bimodal, 36 bilateral). Speech recognition was assessed in a standard clinical test environment with a single loudspeaker using the minimum speech test battery for adult CI recipients as well as with an R-SPACETM 8-loudspeaker, sound-simulation system. All participants were tested in three listening conditions for each measure including each ear alone as well as in the bilateral/bimodal condition. In addition, we asked each bimodal listener to provide a yes/no answer to the question, “Do you think you need a second CI?”
This study yielded three primary findings: (1) there were no significant differences between bimodal and bilateral CI performance or binaural summation on clinical measures of speech recognition, (2) an adaptive speech recognition task in the R-SPACETM system revealed significant differences in performance and binaural summation between bimodal and bilateral CI users, with bilateral CI users achieving significantly better performance and greater summation, and (3) the patient’s answer to the question, “Do you think you need a second CI?” held high sensitivity (100% hit rate) for identifying likely bilateral CI candidates and moderately high specificity (77% correct rejection rate) for correctly identifying listeners best suited with a bimodal hearing configuration.
Clinics cannot rely on current clinical measures of speech understanding, with a single loudspeaker, to determine bilateral CI candidacy for adult bimodal listeners nor to accurately document bilateral benefit relative to a previous bimodal hearing configuration. Speech recognition in a complex listening environment, such as R-SPACETM, is a sensitive and appropriate measure for determining bilateral CI candidacy and also likely for documenting bilateral benefit relative to a previous bimodal configuration. In the absence of an available R-SPACETM system, asking the patient whether or not s/he thinks s/he needs a second CI is a highly sensitive measure, which may prove clinically useful.
1Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN, 37232, USA; and
2Department of Speech and Hearing Science, Arizona State University, Tempe, AZ 85287, USA.
ACKNOWLEDGMENTS: This work was supported by NIH R01 DC009404 and NIH R01 DC010821. Portions of this dataset were presented at the 2015 meeting of the Acoustical Society of America in Pittsburgh, PA, and the 2018 International Conference on Cochlear Implants and other Implantable Auditory Technologies (CI2018) in Antwerp, Belgium.
Michael Dorman is a consultant for Advanced Bionics and MED-EL. Rene Gifford is a member of the audiology advisory boards for Advanced Bionics and Cochlear and the clinical advisory board for Frequency Therapeutics.
Address for correspondence: René H. Gifford, Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA. E-mail: rene.gifford@Vanderbilt.edu
Received October 5, 2017; accepted August 2, 2018.