Evaluatıon of cochlear functıons and effects of noıse exposure ın babıes who were hospıtalızed ın Gazı Unıversıty Neonatal Intensıve Care Unıt

Thirty two infants that had been admitted to Gazi University Hospital,Neonatal Intensive Care Unit were included in this study. Thereafter, the ambiantnoise exposure was determined via measurements of frequency (Hertz) and soundpressure levels (decibel). Our aim was to evaluate the adverse affects of noise onhearing and neurological outcomes. Noise levels were recorded continouslyduring the hospitalization period. TEOAE, DPOAE and ABR tests were used toassess hearing. Hearing tests were performed before discharge and at sixth monthsof life. Neurological outcome was assessed with Bayley II Infant DevelopmentScale.Noise levels were recorded during the hospitalization period and meanrecording time was 162,2 ± 134,9 hours. At 50,1 ± 13,9 % of hospitalizationperiod, infants were exposed to higher noise levels (above of 45 dB) than therecommended level stated by AAP. In spectral analysis of the noise, levelsexceeding 45 dB and also 65 dB, were mostly below 124 Hz. Major source of thenoise was traced back to the incubators.Before discharge from NICU all infants were screened for hearing loss.All patients passed the tests including TEOAE and ABR. On the sixth monthfollow up; TEOAE and DPOAE were performed and no hearing loss was detectedagain.85Hospitalized infants had lower DPOAE SNR amplitudes (dB) at fivefrequencies including 1001, 1501, 3003, 4004, 6006 Hz. DPOAE pass rates at1001 and 1501 Hz were significantly lower compared with healthy subjects.Infants who failed the test at 1001 and 1501 Hz, had been exposed to noise atlonger periods of time, above the recommended level of 45 dB and 65 dB. Wedetected a positive correlation between noise exposure (above 45 dB, above 65dB, mean noise level and maximum noise level) and duration of hospitalization.Infants who failed at 1001 and 1501 Hz had similiar Bayley II InfantDevelopment Scale scores and there were no difference between groups.In conclusion, high noise levels above recommended levels were recordedat Gazi University Hospital NICU and the major noise source in NICU was foundto be the incubators. Although hearing loss was not detected in any infants,hearing thresholds were increased at some frequencies. Ambient noise was mostlyabove recommended levels and this was thought to adversely affect the hearingtests performed at sixth months of life. This study increased the awareness of ourNICU?s physical condition and some arrangements should be planned to reducenoise levels.