An investigation into the clinical utility of ipsilateral/ contralateral asymmetries in bone-conduction auditory steady-state responses

Abstract

Objective: To determine whether ipsilateral/contralateral asymmetries in the bone-conduction (BC) ASSR are robust enough in infants to be used clinically to isolate the test ear. Design: Retrospective investigation of three two-channel BC ASSR datasets. Subjects: Forty-eight adults (mean age 26.7 years), 49 infants (mean age 29.6 weeks). Methods: BC ASSR stimuli were presented as amplitude/frequency modulated sinusoidal tones with carrier frequencies of 500, 1000, 2000, and 4000 Hz (−10 to 45 dB HL). Results: Infants showed greater differences in ipsilateral/contralateral mean amplitudes and phase delays for all experimental conditions compared to adults. Ninety percent of infants had ipsilateral/contralateral asymmetries at 500 and 4000 Hz (20–35 dB HL) using an “amplitude or phase delay” criterion, and at 4000 Hz (20–25 dB HL) using an “amplitude and phase delay” criterion. Conclusions: As ipsilateral/contralateral asymmetries are not consistently present for 1000- and 2000-Hz BC ASSRs in infants, clinical masking would be needed at these frequencies to isolate the test ear. For 500- and 4000-Hz BC ASSRs, the accuracy of using these asymmetries requires clinical confirmation in a group of infants with hearing loss.

Key Words::

• Auditory steady-state response
• ipsilateral/contralateral asymmetry
• bone-conduction ASSR
• infant bone-conduction hearing

Acknowledgements

This research was supported by a Discovery Grant to Dr. Susan Small from the Natural Sciences and Engineering Research Council of Canada. Portions of this paper were presented at the XXIII Biennial Symposium of the International Evoked Response Audiometry Study Group (New Orleans, USA, June 9–13, 2013).

Declaration of interest: The authors report no conflicts of interest.