Background and Aim Neonatal Intensive Care Unit (NICU) is a noisy environment in which infants can be exposed to high noise levels. The aim of the study is to evaluate the adverse effects of noise on hearing and, neurological outcomes of NICU graduates at six months of age.
Methods Thirty two infants that had been admitted to Gazi University Hospital NICU and 25 healthy controls, were included in the study. Noise levels were recorded continously during hospitalization period. TEOAE, DPOAE and ABR tests were used to assess hearing. Neurological outcome was assessed with Bayley II Infant Development Scale.
Results The median period of noise exposure above 45 dB, was 50.1% of the entire hospitalization period. Levels exceeding 45 dB were mostly below 124 Hz. Major source of noise was traced back to the incubators. All patients passed the hearing screening tests before discharge. On the sixth month follow up; hospitalized infants had lower DPOAE SNR amplitudes (dB) at five frequencies including 1001, 1501, 3003, 4004, 6006 Hz in both ears. DPOAE fail rates at 1001 Hz and 1501 Hz were higher in hospitalized infants (p=0.001). Positive correlation between noise exposure and duration of hospitalization was determined. Infants who failed at 1001 and 1501 Hz had similar Bayley II Infant Development Scale scores and there were no difference between groups.
Conclusion Major noise source in NICU was found to be the incubators. Although hearing loss was not detected in any infants, hearing tests at sixth months of life were adversely affected.