Spectral analysis of noise in the neonatal intensive care unit.

OBJECTIVE: To perform spectral analysis of noise generated by equipments and activities in a level III neonatal intensive care unit (NICU) and measure the real time sequential hourly noise levels over a 15 day period. METHODS: Noise generated in the NICU by individual equipments and activities were recorded with a digital spectral sound analyzer to perform spectral analysis over 0.5 - 8 KHz. Sequential hourly noise level measurements in all the rooms of the NICU were done for 15 days using a digital sound pressure level meter . Independent sample t test and one way ANOVA were used to examine the statistical significance of the results. The study has a 90 % power to detect at least 4 dB differences from the recommended maximum of 50 dB with 95 % confidence. RESULTS: The mean noise levels in the ventilator room and stable room were 19.99 dB (A) sound pressure level (SPL) and 11.81 dB (A) SPL higher than the maximum recommended of 50 dB (A) respectively ( p < 0.001). The equipments generated 19.11 dB SPL higher than the recommended norms in 1 - 8 KHz spectrum. The activities generated 21.49 dB SPL higher than the recommended norms in 1 - 8 KHz spectrum ( p< 0.001).The ventilator and nebulisers produced excess noise of 8.5 dB SPL at the 0.5 KHz spectrum. CONCLUSION: Noise level in the NICU is unacceptably high .Spectral analysis of equipment and activity noise have shown noise predominantly in the 1 - 8 KHz spectrum. These levels warrant immediate implementation of noise reduction protocols as a standard of care in the NICU.