Panasonic WX-LA20 User manual

Classroom Acoustics: A Failing Grade
(Summary)
Hearing Health, Sept/Oct 1998, pp. 11-16,59
Carl C. Crandell, Ph.D.
Recent investigations of the acoustical properties of classrooms and their impact
on students have revealed disturbing findings. Inappropriate acoustics can
negatively influence speech perception, on-task behavior, reading and spelling
ability, behavior, attention, concentration, and academic achievement. This is
extremely troubling for classrooms that house younger students as young
children require better acoustical environments than adults with normal hearing
to achieve equivalent perception scores.
A study conducted in the 80’s demonstrated that noise was the sole factor for 50
– 75% of variant reading delays of elementary school children. When classroom
noise was reduced through acoustical modification, increases in concentration,
attention, and participation were seen. Acoustical improvements for classroom
environments include:
1. Acoustical modifications
The optimum levels for classroom acoustics are +15 dB signal to noise ratio
(SNR) and reverberation (reflected sound energy) times should not surpass 0.4
seconds. In 1995, a survey of 32 classrooms showed that only 7 met
recommended reverberation times and none achieved recommended noise
levels. An explanation for this lies in the fact that only a little more than half (59%)
of the rooms were carpeted, 15% had acoustical wall modifications, 3%
contained partitions or drapes, and none of the rooms had acoustically modified
furniture.
2. Reduction of speaker-to-listener distance (SLD)
This allows for the direct sound field to dominate the communication. When the
SLD is increased, the indirect sound field dominates the listening environment.
Speech recognition is only optimal within the direct sound field. To reduce poor
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classroom acoustics, close SLD should be utilized whenever possible. One way
to improve SLD is to use small group instruction over traditional seating
arrangements.
3. Utilization of classroom amplification
The implementation of classroom amplification can decrease SLD and
significantly affect speech perception. The Mainstream Amplification Resource
Room Study (MARRS, 1981) demonstrated drastic improvements in academic
achievement when students received amplified instruction.
By increasing the teacher’s voice by approximately 10 dB and providing a
uniform sound field throughout the classroom, students display perceptual and
psycho-educational improvements.
The large body of acoustic research in classrooms supports the need for good
acoustics in teaching environments. Several strategies can alleviate the
damaging effects of poor acoustics, one of which includes sound field
amplification. By adopting these solutions and strategies, it will be in the best
interest of the students.
Classroomaudi[email protected]
877.268.7215