Otoacoustic emissions and persistent tinnitus after acute acoustic trauma.
OBJECTIVE
To follow up the auditory status of military personnel after an acute acoustic trauma and to identify the possible predictive value of hearing thresholds and otoacoustic emissions during the first 24 hours after the acoustic trauma.


METHODS
A group of 24 young military subjects, aged 22 +/- 2.3 years, without any otologic problem before the acoustic trauma, were examined at three time intervals after an accidental acoustic trauma caused by the discharge of a firearm: 24 hours, 72 hours, and 15 days.


METHODS
Each subject was submitted to medical examination and to a questionnaire detailing the circumstances of the acoustic trauma. Pure tone audiometry was performed from 1 to 8 kHz per half octave. Transiently evoked otoacoustic emissions were recorded in the nonlinear mode at 80 dB pSPL, and distortion product otoacoustic emissions were recorded from 1 to 6 kHz, using a distortion product-gram type procedure, at 65/55 dB SPL, with f2/f1 = 1.22. Two groups of subjects were defined: group 1 (n = 8) represented subjects with short-lasting tinnitus (<72 h) and group 2 (n = 16) subjects with long-lasting tinnitus (>72 h).


RESULTS
Hearing thresholds did not differ significantly between these two groups 24 hours after the acoustic trauma. However, otoacoustic emissions showed significantly lower amplitudes 24 hours after the acoustic trauma in subjects showing a longer lasting tinnitus.


CONCLUSIONS
Otoacoustic emissions appear to be a better predictor of the persistence of tinnitus than hearing thresholds alone 24 hours after an acute acoustic trauma.
Nottet
Jean-Bertrand
JB
Hôpital d'Instruction des Armées Desgenettes, Service ORL, Lyon, France.
Moulin
Annie
A
Brossard
Nicolas
N
Suc
Benoît
B
Job
Agnès
A
D000208:Acute Disease; D000328:Adult; D001301:Audiometry, Pure-Tone; D001309:Auditory Threshold; D006317:Hearing Loss, Noise-Induced / Q000150:complications* / Q000503:physiopathology*; D006801:Humans; D008889:Military Personnel; D017084:Otoacoustic Emissions, Spontaneous / Q000502:physiology*; D013997:Time Factors; D014012:Tinnitus / Q000209:etiology*