SFA/Sound Enhancement Systems

Sound Field Amplification (SFA) or Sound Enhancement Systems (SES) are used in schools to enhance students' ability to clearly hear the teacher's voice. Research shows use of SFA/SES:

  • Improves academic test scores
  • Improves student attention and on-task behavior
  • Increases classroom interaction and participation
  • Overcomes high levels of ambient noise in classrooms
  • Improves word and sentence recognition
  • Reduces classroom stress
  • Decreases teacher absenteeism caused by voice and throat illnesses


These units should evenly distribute the teacher's voice throughout the classroom and create a positive signal-to-noise ratio of +10 to +15 decibels (dB). Even distribution of the teacher's voice means that, if the microphone is 5-6" from the teacher's mouth, it has the same effect as if the teacher were standing 5-6" from each student's ear, something no one person could physically accomplish. The positive signal-to-noise ratio means that the teacher's voice is 10-15 dB louder than the classroom noise. For a frame of reference, a whisper is only 20 dB, so the "amplification," when done properly, should be just below the level of a whisper louder than the classroom noise! This is why we have come to prefer the term "Sound Enhancement System." Adults may have enough mild hearing damage done over time that they will have difficulty detecting this subtle difference.