Frequency Following Response and Speech Recognition Benefit for Combining a Cochlear Implant and Contralateral Hearing Aid.

Only 14 adults were tested, and only 12 had usable brainstem records, so the correlations are unstable. The study was correlational and cross-sectional. It cannot show that a stronger brainstem response causes more bimodal benefit. Many comparisons were run. After correction, only the link between brainstem voice-pitch amplitude and single-word benefit in quiet remained significant. Participants had usable low-frequency hearing in the nonimplanted ear, and no 125 Hz threshold exceeded 65 dB HL, so the results may not apply to patients with profound low-frequency loss. The brainstem response to the 700 Hz vowel feature was very small, likely because hearing loss reduced audibility, so the study could not test whether that feature predicts benefit. Two brainstem records were excluded because the stimulus was presented at 80 dB SPL instead of 90 dB SPL. Age was not controlled, although age did not correlate with brainstem amplitude in this sample. The FFR stimulus was presented at a fixed level, so it is unclear whether differences in audibility influenced the response. The speech benefit measure changed the result: relationships were stronger for raw acoustic benefit than for normalized acoustic benefit, and the authors did not establish which method is clinically preferable. The authors state that further investigation is needed to understand the relationship between FFR amplitude and bimodal benefit.

The only supplied funding statement is that the National Institute on Deafness and Other Communication Disorders funded the work.

Do not conclude that the FFR can guide cochlear implant decisions. The study had 12 usable FFR records, and only the correlation with single-word benefit in quiet remained significant after multiple comparisons. It did not show that the test predicts benefit for an individual patient.