Effects of High Sound Exposure During Air-Conducted Vestibular Evoked Myogenic Potential Testing in Children and Young Adults.
Amanda I Rodriguez, Megan L A Thomas, Denis Fitzpatrick and 1 others
PMID 29466264WHAT IT FOUND
Children's ears received higher sound pressure than adults' ears during VEMP testing, and small ear canals could push exposure above a suggested safety limit.
At the lower settings used here, hearing thresholds and otoacoustic emissions did not change.
Key findings
01Children had higher ear-canal sound pressure levels than adults during VEMP stimuli, by 2.2 to 2.9 dB at each intensity for 500 and 750 Hz tone bursts.
02Smaller ear-canal volume was associated with higher ear-canal sound pressure, and children with ear-canal volume under 0.8 mL were considered at risk for exceeding the 132 dB sound-energy cutoff.
03With the study's VEMP levels, 120 dB SPL in children and 125 dB SPL in adults, no hearing threshold shift exceeded 5 dB, no distortion product otoacoustic emission amplitude fell outside the expected pre-test range, and no subjects reported ear symptoms.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
The study included only 15 children and 10 to 12 adults, all with normal hearing, so it does not show what happens in children with hearing loss, vestibular symptoms, or middle-ear disease. Hearing thresholds and otoacoustic emissions were checked only immediately after testing, not days or weeks later, so delayed effects were not assessed. The children were 4 to 12 years old; the paper did not measure children younger than 4, whose ear canals may be smaller. The safety conclusion depends on a sound-energy calculation and a 132 dB cutoff that the authors note is debated for VEMP testing. The Phase II protocol used short 4 msec stimuli and only two trials; protocols with more repetitions, longer stimuli, or higher levels may deliver more energy. One child could not answer the symptom questionnaire, and symptom reporting relied on parent report.
Declared interests
The authors declared no conflict of interest. The supplied publication types list NIH extramural research support.
The easy way to misread this
Do not read the lack of hearing threshold or DPOAE changes as proof that any VEMP protocol is safe for children. The study used short 4 msec stimuli, 500 Hz tone bursts, and only two trials, and it tested children aged 4 to 12 with normal hearing. Standard 125 dB SPL in children with ear-canal volume under 0.8 mL was reported as potentially exceeding the 132 dB sound-energy cutoff.