To study normative thresholds and latencies for click and tone-burst auditory brainstem response (TB-ABR) for air and bone conduction in normal infants and those discharged from neonatal intensive care units, who passed newborn hearing screening and follow-up distortion product otoacoustic emission. An evoked potential system (Vivosonic Integrity) that incorporates Bluetooth electrical isolation and Kalman-weighted adaptive processing to improve signal to noise ratios was employed for this study. Results were compared with other published data.
One hundred forty-five infants who passed two-stage hearing screening with transient-evoked otoacoustic emission or automated auditory brainstem response were assessed with clicks at 70 dB nHL and threshold TB-ABR. Tone bursts at frequencies between 500 and 4000 Hz were used for air and bone conduction auditory brainstem response testing using a specified staircase threshold search to establish threshold levels and wave V peak latencies.
Median air conduction hearing thresholds using TB-ABR ranged from 0 to 20 dB nHL, depending on stimulus frequency. Median bone conduction thresholds were 10 dB nHL across all frequencies, and median air-bone gaps were 0 dB across all frequencies. There was no significant threshold difference between left and right ears and no significant relationship between thresholds and hearing loss risk factors, ethnicity, or gender. Older age was related to decreased latency for air conduction. Compared with previous studies, mean air conduction thresholds were found at slightly lower (better) levels, while bone conduction levels were better at 2000 Hz and higher at 500 Hz. Latency values were longer at 500 Hz than previous studies using other instrumentation. Sleep state did not affect air or bone conduction thresholds.
This study demonstrated slightly better wave V thresholds for air conduction than previous infant studies. The differences found in the present study, while statistically significant, were within the test step size of 10 dB. This suggests that threshold responses obtained using the Kalman weighting software were within the range of other published studies using traditional signal averaging, given step-size limitations. Thresholds were not adversely affected by variable sleep states.
This study measured normative thresholds and latencies for tone-burst ABR for air conduction and bone conduction in 145 normal- hearing newborns and infants discharged from the well-baby nursery and NICU, who all passed NHS. A system that employs Bluetooth electrical isolation and adaptive processing using Kalman weighted averaging techniques was employed for this study. This study demonstrated slightly better Wave V thresholds for air conduction than previous infant studies. The differences found in the current study, while statistically significant, were within the test step size of 10 dB. This suggests that threshold responses obtained using the Kalman weighting software were within the range of other published studies using traditional signal averaging, given step-size limitations.
1Communication Sciences Research Center, Division of Audiology, Cincinnati Children’s Hospital Medical Center, Cincinnati, Ohio, USA; 2Physical Acoustics Laboratory, Boys Town National Research Hospital, Omaha, Nebraska, USA; 3National Center for Rehabilitative Auditory Research, Portland, Oregon, USA; 4Department of Otolaryngology, Oregon Health & Science University, Portland, Oregon, USA; 5Department of Audiology, Pacific University, Forest Grove, Oregon, USA; and 6Department of Rehabilitation and Physical Therapy, Good Samaritan Hospital of TriHealth, Inc., Cincinnati, Ohio, USA.
This work was supported by a grant (award number R01 DC010202) from the National Institute of Deafness and other Communication Disorders of the National Institutes of Health and by a grant (DC010202-01S1) from the American Recovery and Reinvestment Act of 2009 supplement. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The content of this article does not represent the views of the Department of Veterans Affairs or the United States Government.
The authors declare no other conflict of interest.
Received April 29, 2014; accepted January 26, 2015.
Address for correspondence: Lisa L. Hunter, Communication Sciences Research Center, Cincinnati Children Hospital Medical Center, 241 Sabin Way, ML 15008, Cincinnati, OH 45229, USA. E-mail: email@example.com