Abstract
This study aimed to evaluate the effects of complete external ear canal occlusion on hearing thresholds with aging. The goal was to decide which tuning fork is more appropriate to use for the contralateral occlusion test (COT), in individuals of different ages. Forty-two normal hearing subjects between 21 and 67 years were divided into three age groups (20-30 years, 40-50 years, and 60-70 years). Participants underwent sound field audiometry tests with warble tones, with and without ear canal occlusion. Each ear was tested with the standard frequencies (250, 500, 1000, and 2000 Hz). The contralateral ear was suppressed by masking. Hearing thresholds showed an increase as the frequency increased from 20.85 dB (250 Hz, 20-30 years group) to 48 dB (2000 Hz, 60-70 years group). The threshold differences between occlusion and no occlusion conditions were statistically significant and increased ranging from 11.1 dB (250 Hz, 20-30 years group) to 32 dB (2000 Hz, 20-30 years group). We found statistically significant differences for the three age groups and for all evaluations except to 500 Hz difference and average difference. The mean hearing loss produced by occlusion at 500 Hz was approximately 19 dB. We found no statistically significant differences between right and left ears and gender for all measurements. We conclude that the use of the 512 Hz tuning fork is the most suitable for COT, and its use may allow clinicians to distinguish mild from moderate unilateral conductive hearing loss.
Highlights
Many of the early diagnostic tests are initially performed at bedside[1,2]
This study aimed to evaluate the effects of complete occlusion of the external auditory meatus (EAM) on hearing thresholds with aging in order to decide which tuning fork is more appropriate for contralateral occlusion test (COT) in individuals of different ages
If the sound of the tuning fork lateralizes to the affected ear, it suggests that the ear has a moderate or severe hearing loss; if the sound of the tuning fork lateralizes to the normal ear, it suggests that the ear has a mild hearing loss
Summary
Many of the early diagnostic tests are initially performed at bedside[1,2]. This practice may decrease turnaround time, reduce costs, and improve decision making[3,4,5]. After the confirmation of unilateral conductive hearing loss with Weber and Rinne tests[10,11,12,13,14,15], the COT is carried out with total occlusion of the external auditory meatus (EAM) of the contralateral ear (the unaffected ear). This will produce a hearing loss in the unaffected ear that can be higher, lower, or similar to that in the affected ear. The sound of a vibrating tuning fork placed in the middle of the forehead will lateralize to the ear with the greater hearing loss
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