Improving Classroom Acoustics: Low to High Tech Strategies

1. Improving Classroom Acoustics: Low to High Tech Strategies October 25, 2013 Diane L. Meyer and Mike Brummer

3. Did you know? That normal hearing children can miss as much as 1/3 of what their teacher says due to poor classroom acoustics. Even in an acoustically ‘good’ classroom, children ‘receive’ 83% of a teacher’s voice ‘signal’ when they are seated in the front row; 66% in the middle rows and only 55% in the back row. (Crandell & Smaldino, 1994) A child's hearing abilities are not fully developed until age 15. Children cannot hear and neurologically process what they hear the same as an adult. (Crandell1995; Flexer 2002) Up to 43% of primary level students fail a minimal 15 dB hearing screening on any given day, in part due to the 14.9% (or approximately 8 million) school-aged children that have a permanent hearing loss and the 10-15% of children that have a temporary hearing loss from middle ear infections. (MARRS-U.S. Dept. of Education Study; American Medical Association )

4. The teacher’s voice drops 6 decibels for every doubling of distance meaning that children seated in the middle to back rows have significantly greater difficulty attending to the teacher’s verbal instruction. In 1996, the United Nations issued a report over the concern that 10-12% of school-aged boys in the United States were being prescribed the drug Ritalin. During the 1990’s there was a 700% increase in the use of psychostimulants in the United States. Effectively, the U.S. was consuming over 90% of 8.5 tons of Ritalin produced world-wide each year.

5. Instructional Message: Inverse Square Law The teacher’s voice decreases 6 decibels as the distance from him/her doubles. Ambient classroom noise may mask the teacher’s voice for students sitting in the middle and back of the classroom. http://www.classroomhearing.org/Videos/Inverse_Square_Law.html Factors Affecting Acoustic Access

6. Inverse Square Law

7. Children’s Listening Abilities Children’s cognitive auditory capabilities are not fully developed until age fifteen. This means that children do not hear and process what they hear, the same as an adult. Therefore they cannot understand the difference between sounds comprehend what they are hearing the same as an adult. They must exert more energy than an adult to concentrate on and process the sounds they are hearing. Because of these immature auditory abilities, children require a better acoustical environment than does an adult in order to understand what they are hearing.1

8. 2Acoustical Surfaces Inc.

9. Background Noise Sources Through walls from adjacent classrooms Over the ceiling from adjacent classrooms Through doors, around the frame and under the door Through ventilators or louvers above door units Through HVAC ductwork from adjacent rooms HVAC noise from ceiling diffusers Through the light fixtures From outside, through exterior walls and windows From floor above

10. Strategies to Improve Acoustic Access

11. Environmental Strategies Areas to Consider • Ceiling • Floors • Windows • Walls and Doors • Seating and Furniture • Ventilation • Lighting • Special Purpose Areas

12. Ceiling Installing acoustical ceiling tile is the most effective way of absorbing distorted middle and high frequency noise and improving speech perception ability. A ceiling height less than 12 feet is optimal for the listening environment. Suspend banners, student work, and hanging plants from the ceiling

13. Floors Carpeting absorbs excessive reverberation of high frequency consonant sounds dampens noise from students and movement of classroom furniture Use rubberized or resilient tile versus flat, reflective tile Use area rugs or carpeting for uncarpeted areas

14. Windows Drapes on the sides of windows absorb sound Keep windows closed to prevent outside sounds from entering the classroom

15. Walls and Doors Place rectangular extension rods in opposite corners of the room and hang a curtain Creates round corners to reduce reverberation Provides small storage area • Place cabinets at angles in the corners –soften the fronts with fabric curtains on magnetic rods or cover with cork boards

16. Seatingand Furniture Place a drape or cork on the front of solid areas teacher’s desk Use curtains to cover/conceal open shelving units Use tennis balls or rubber chair leg caps on tables and chairs

17. Think about traffic flow in the room: where is supplies kept in relation to your teaching zones Place noisy items (pencil sharpener) away from teaching areas Create assigned zones during small group work so that groups are spread out

18. Ventilation Replace noisy blowers Cover ventilation openings with strips of material Do not use desk or floor fans

19. Lighting Make sure florescent lights are functioning correctly Ballast will make high frequency sounds when they begin to burn out If your room is equipped with a motion sensor, position students with hearing aids out of the directional path of the doorway

20. Special PurposeAreas Carpeting Use rubberized or resilient tile versus flat, reflective tile Hang banners or flags from the ceiling Place material or cloth banners on the walls

21. Instructional Strategies • Rate of Speech • Immature central nervous system needs a slower rate of speech in order to process the acoustic linguistic code • PK to 3rd grade need 120 words/minute • 4th grade can process 124 to 128 words /minute • Middle school can process 135 words per minute • High school can process 145 words per minute • Model a Preschool or Kindergarten teacher rate

22. Repeating of peers’ questions, comments, answers • Inverse Square Law – signal decreases 6 dB every time distance doubles • Students 20 feet from speaker will function like a person with a mild hearing loss • Repeat/Rephrase/Summarize all verbal communications • Control competing background noise • Close doors • Turn off radios • Use headphones for computer centers

23. Face students when speaking • Address the students when instructing • Speech signal travels through the air to the students’ ears versus traveling to the board reflecting off the board • Allows students to access the speaker’s face for any visual support • Talk at a normal volume level • Increasing the volume increases the distortion of the auditory signal • Increasing the volume alters how you produce speech sounds making it difficult to speechread

24. Technological Solutions Classroom instruction with assistance Classroom instruction without assistance

25. SoundfieldSystems • Surround sound systems for teachers and students • Group or classroom systems for instruction of large audiences • Personal systems for individuals with hearing loss • Can be wired or portable

26. References 2Acoustical Surfaces Inc. http://www.acousticalsurfaces.com/soundproofing_tips/html/crashcourse.htm Banotal, Alyssa (2008). “How to Talk to Children” – Linguistic ability and the CNS. Advance Magazine, Vol. 18, Issue 3, p. 6. Crandell, Carl, and Smaldino, Joseph (1994). “The importance of room acoustics”. In R. Tyler & D. Schum (Eds.), Assistive listening devices for the hearing impaired (pp. 142-164). Baltimore,MD: Williams & Wilkins. TED: “Why Architects Need to Use their Ears” - Classroom Acoustics by Julian Treasure http://www.ted.com/talks/julian_treasure_why_architects_need_to_use_their_ears.html 1The Institute for Enhanced Classroom Hearing www.classroomhearing.org