Classroom A/V: Improving the Sound Field
By: Tim Schnabel
Researchers estimate that school-age children spend as much as 75 percent of the school day engaged in listening activities. Unfortunately, the typical classroom has acoustical characteristics—such as background noise, reverberation, and distances—that are detrimental to students with normal hearing, as well as students with a hearing loss or hearing difficulties. One of the ways to overcome these barriers to learning is to create a sound field in the classroom.
What Is a Sound Field?
A sound field is the area within a classroom where the teacher’s voice is distributed at a consistent level. This sound field is created by a classroom sound system specifically designed to slightly amplify the teacher’s voice using a microphone, audio amplifier, and speakers placed strategically throughout the room.
Ideally, the voice amplification components are integrated into the existing classroom A/V system. It is not uncommon to start with a basic sound field system and upgrade later to a complete A/V switching and control system.
A Proven Concept
The concept of a sound field is not new. Studies identifying the benefits of these systems go back as far as 25 years. The rationale underlying sound field systems is very simple: how well children hear a teacher affects how well they learn. The more they can hear, and the less they have to strain and guess, the better chance they will have of learning.
The purpose of the system is to ensure that the teacher’s voice is clearly audible above the background sounds at all instructional locations within the room. Students in the back row, and throughout the class, need to hear as well as those in the front row. Several studies, such as the Mainstream Amplification Resource Room Study (commonly referred to as the MARRS Project), have identified the benefits of sound field systems.
Benefits for Teachers and Students
It is clear from numerous studies that the use of a classroom amplification system results in improvements in the classroom environment, student academic achievement, and teacher health.
Studies show evidence of increased student attention, improved speech recognition, fewer distractions, and decreased off-task behavior. Schools that use classroom amplification technology have reported significant decreases in teacher absences due to voice fatigue and vocal strain. The use of classroom amplification has been embraced and supported by students, parents, and school staff.
What follows is a sampling of just some of the results measured by research projects.
Student Achievement
Educators and researchers have documented measurable results in student achievement in classrooms that use voice amplification.
In Minnesota, the reading, math, and spelling skills of second-grade students were tested three times over six months in one unamplified and one amplified classroom. Students in the amplified classroom posted significantly greater gains in reading and spelling. No significant difference in gains in math scores was measured between the two groups.
Classroom amplification systems in southern Illinois schools were researched as part of the MARRS Project. Researchers reported that the number of students referred to special education in kindergarten to sixth grade dropped by 43 percent in amplified classes of students with and without hearing impairment.
Student Attentiveness
Research has shown that improved classroom environments are a direct result of the use of classroom amplification.
In 2000, a study comparing unamplified and amplified first-grade classrooms in Broward County Public Schools in Florida reported that teachers in amplified classrooms observed positive changes in students’ attentiveness and classroom participation.
The MARRS Project found that the use of classroom amplification systems results in easier classroom management related to increased student attention, decreased discipline problems, less student distraction, and less need to repeat instructions.
First-grade teachers in Minnesota observed that their students were “less distracted, more attentive” and required “less repetition of directions” after the introduction of amplification systems into their classrooms.
Teacher Benefits
Classroom amplification systems allow teachers to spend the day speaking at a natural level, which significantly reduces voice strain and vocal fatigue.
Teachers in amplified classrooms in Iowa reduced their absenteeism by 36 percent, which was directly related to a decrease in vocal health issues, such as voice, jaw, and throat problems.
Florida teachers in amplified classrooms reported decreased vocal strain and fatigue, and a multi-year study in Florida’s Orange County Public Schools found a 25 percent decrease in teacher absenteeism in amplified classrooms.
Researchers in the MARRS Project found that voice fatigue and teacher absences due to vocal strain in amplified classrooms decreased from 15 percent to an average of 2 to 3 percent in one year.
Designing an Effective Sound Field System
The key to success is not simply sound amplification, but increased intelligibility with equal voice level for each student. The purpose of the system is to ensure that the teacher’s voice is clearly audible above the background sounds at all instructional locations within the room.
Students in the back row, and throughout the class, need to hear as well as those in the front row. To achieve this goal, an effective sound field system must accomplish the following:
* Raise the level of the teacher’s voice to 15dB above classroom background noise
* Distribute sound evenly to each student throughout the entire classroom by using multiple speakers
* Provide superior audio performance in frequencies associated with the human voice and full-range reproduction of program audio
* Minimize distorted sound
Tim Schnabel is director of education programs for Extron Electronics, a leading manufacturer of A/V system integration solutions for schools and universities, www.extron.com.
