In classrooms around the country, students are straining to hear.
Desks squeak, children chatter, computers hum, heaters rumble.
Ear infections muffle the teacher's words for some youngsters. Others are hampered by a slight hearing loss that hasn't been diagnosed. Even children who hear well can miss out because of poor acoustics. So Straub and many of her colleagues are now wired for sound, leading classes through small public-address systems that broadcast their words to every corner of the room. Experts cite a growing body of research indicating that academic achievement goes up and inappropriate behavior goes down in amplified teaching areas.