Evaluation of cochlear function in normal-hearing young adults exposed to MP3 player noise by analyzing transient evoked otoacoustic emissions and distortion products.
OBJECTIVE
Exposure to recreational noise may cause injuries to the inner ear, and transient evoked (TEOAEs) and distortion product otoacoustic emissions (DPOAEs) may identify these cochlear alterations. The goal of this study was to evaluate TEOAEs and DPOAEs as a method to diagnose early cochlear alterations in young adults exposed to MP3 player noise.


METHODS
We performed a prospective study of the cochlear function in normal-hearing MP3 player users by analyzing TEOAE and DPOAE incidence, amplitude, and spectral content. We gathered a sample of 40 ears from patients between 19 and 29 years old (mean age 24.09 years, SD 3.9 years). We compared the results with those of a control group of 232 ears not exposed to MP3 noise from patients aged 18 to 32 years (mean age 23.35 years, SD 2.7 years). Fifty percent of ears were from females and 50% were from males.


RESULTS
Subjects who had used MP3 players for most years and for more hours each week exhibited a reduction in TEOAE and DPOAE incidence and amplitudes and an increase in DPOAE thresholds. TEOAEs showed a statistically significant lower incidence and amplitudes for normal-hearing subjects using MP3 players at frequencies of 2000, 3000, and 4000 Hz. DPOAE incidence was lower at 700, 1000, 1500, and 2000 Hz; the amplitudes were lower at frequencies between 1500 and 6000 Hz; and the thresholds were higher for all frequency bands, statistically significant at frequencies from 1500 to 6000 Hz, p < .05.


CONCLUSIONS
Cochlear impairment caused by MP3 player noise exposure may be detectable by analyzing TEOAEs and DPOAEs before the impairment becomes clinically apparent.
Santaolalla Montoya
Francisco
F
Department of Otorhinolaryngology, Basurto Hospital, School of Medicine, University of the Basque Country, Bilbao, Spain. francisco.santaolalla@ehu.es
Ibargüen
Agustín Martinez
AM
Vences
Ana Rodriguez
AR
del Rey
Ana Sanchez
AS
Fernandez
Jose Maria Sanchez
JM
D000158:Acoustic Impedance Tests / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D001309:Auditory Threshold / Q000502:physiology; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003051:Cochlea / Q000502:physiology; D005260:Female; D006317:Hearing Loss, Noise-Induced / Q000175:diagnosis* / Q000453:epidemiology; D006801:Humans; D055539:MP3-Player; D008297:Male; D009622:Noise / Q000009:adverse effects*; D017084:Otoacoustic Emissions, Spontaneous; D038781:Otoscopy / Q000379:methods; D010469:Perceptual Distortion / Q000502:physiology; D011336:Probability; D011446:Prospective Studies; D012016:Reference Values; D018570:Risk Assessment; D055815:Young Adult