Contribution of heating, ventilation, and air conditioning airflow and conversation to the ambient sound in a neonatal intensive care unit.

Sound reduction strategies in the neonatal intensive care unit (NICU) must focus on the sources of excessive sound. We studied the relative contribution of personnel conversation and heating, ventilation, and air conditioning (HVAC) airflow by measuring several parameters of sound during four environmental conditions: unaltered ambient sound, HVAC airflow off, HVAC airflow and conversation off, and conversation off. All measurements were decreased by interrupting HVAC airflow and conversation. The reduction was greater when conversation was stopped. The method of sound reduction did not change the frequency distribution of sound. Attention to personnel conversation may be effective in lowering sound exposure in the NICU. The contribution of HVAC airflow should be measured in new constructions and renovations.