Investigators	Population	Results Obtained With FM Sound Field Amplification
Allen (1993)	90 general education elementary teachers	(preference) Once familiar with the system, teachers ranked sound field's usefulness above that of other instructional delivery equipment.
Nelson & Schmidt (1993)	20 general education K-3rd grade teachers	(open classroom) Teachers in open classrooms reported greater success than those in traditional classrooms, although all teachers identified benefits.
Osborn, VonderEmbse, & Graves (1989)	47 amplified K-3 regular education classrooms	(teacher's voice) Fewer teachers absences and laryngitis when using sound field amplification
Rosenberg et al. (in press)	55 general education K-2 teachers	(teacher's voice) 100% agreement that reduced vocal strain was the greatest benefit from sound field amplification
Rosenberg (1998)	1 acoustically modified and 1 amplified relocatable classroom	(cost) Sound field amplification was provided at 1/5 the cost of acoustical modifications in newly constructed relocatable classrooms
Rosenberg et al. (1999)	64 general education K-2 amplified classrooms	(cost) Typical classroom (25 students, 1 teacher) daily cost per person was $.14 or $.03/day over 5 years.