Evaluation of noise-induced hearing loss with audiometer and distortion product otoacoustic emissions.

OBJECTIVE: To compare the results of audiogram and distortion product otoacoustic emissions (DPOAEs) parameters between staffs working in a noisy environment and normal subjects. MATERIAL AND METHOD: Hearing function of 32 noise-exposed workers and 18 reference subjects were assessed with DPOAEs and pure-tone audiometry. Results were compared among three groups: 1) ears of reference subjects, 2) audiometrically normal ears of noise-exposed subjects, and 3) audiometrically abnormal ears of noise-exposed subjects. RESULTS: DPOAEs parameters, statistically significant difference were found between group 1 and 2 and group 1 and 3 at all frequencies. Statistically significant differences in pass rate for DPOAEs at 4-6 kilohertz (kHz) were also found between group 1 and 2. CONCLUSION: DPOAEs are more sensitive than audiometry to detect pre-symptomatic inner ear damage. It may play a role as screening and monitoring test for noise-exposed workers.

The high-risk neonatal hearing screening program in Songklanagarind Hospital.

OBJECTIVES: Determine the prevalence and risk factor of neonatal hearing loss in the high-risk group. MATERIAL AND METHOD: A prospective descriptive study, using the criteria of "high-risk" as defined by the Joint Committee of Infant Hearing 1994, American Academy of Pediatrics, 465 newborn in Songklanagarind Hospital were screened with portable otoacoustic emissions (OAEs) before being discharged between July 1st, 2004 and December 31st, 2006. Based on the examinations, the results were divided into two groups, "pass" and "refer". The neonates who failed the screening test were referred for further checks with conventional OAEs and if they failed again, then the authors reassessed them with auditory brainstem responses (ABR). RESULTS: Four hundred fifty eight infants (98.5%) in the high-risk group passed the primary screen for both ears. One infant (0.21%) was confirmed with unilateral sensorineural hearing loss and three infants (0.64%) were confirmed with bilateral hearing impairment above 30 dB. Three infants (0.64%) were lost to follow up. High-risk factors of hearing loss in the present study included 226 infants from premature birth (48.6%), 159 infants exposed to ototoxic medications (34.2%), and 61 infants with respiratory distress syndrome that required mechanical ventilation for at least five days (13.1%). CONCLUSION: Otoacoustic emissions are a very quick and noninvasive technique, and suitable for hearing screening in infants.