Officials at growing districts say the extra aid will help them handle growth. Others say it will keep them from dipping into reserves or cutting programs. Will the infusion provide tax relief to property owners? Don’t count on it, unless boards are willing to roll back their levies substantially.

Some neonatal intensive care units, or NICUs, have established quiet times, during which certain activities are verboten. Some have also switched to single-occupancy, carpeted rooms and added sound monitors. But until now, researchers haven’t looked closely at how well such techniques work.