Effective Masking Levels for Bone Conduction Auditory Brainstem Response Stimuli in Infants and Adults with Normal
1School of Audiology and Speech Sciences, The University of British Columbia, Vancouver, British Columbia, Canada.
Ear and Hearing
|September 14, 2020
Summary
Infants require higher effective masking levels (EMLs) for bone conduction (BC) auditory brainstem response (ABR) testing than adults, especially at lower frequencies. These findings help refine BC-ABR protocols for accurate infant hearing assessments.
Area of Science:
- Audiology
- Neuroscience
- Pediatrics
Background:
- Auditory Brainstem Response (ABR) is crucial for infant hearing assessment.
- Bone Conduction (BC) ABR aids in determining hearing loss type and degree.
- Ear-specific assessment is challenging due to cross-skull cochlear activation.
Purpose of the Study:
- Determine effective masking levels (EMLs) for BC-ABR in infants and adults.
- Investigate EMLs for 500- and 2000-Hz BC stimuli.
- Establish clinical masking guidelines for BC-ABR.
Main Methods:
- Recruited 21 normal-hearing adults and 24 infants.
- Presented 500- and 2000-Hz BC stimuli via a B-71 oscillator.
- Determined EMLs using binaural white noise masking via ER-3A earphones.
Main Results:
- Infants required higher EMLs than adults: 80 dB SPL (500 Hz) vs. 65 dB SPL (500 Hz).
- Infants needed ~13 dB more masking at 500 Hz compared to adults.
- Infants showed greater masking difference between 500 Hz (26 dB) and 2000 Hz (12 dB).
Conclusions:
- Established maximum binaural EMLs for infant BC-ABR.
- Provided recommended monaural masking levels for clinical BC-ABR.
- Highlighted limitations of masking at higher stimulus levels.
