ABSTRACT
Section A: Hearing and Noise ......................................................................................... 111 Introduction ..................................................................................................................... 111
Why Is Noise a Problem? ............................................................................................. 111 “Safe” Noise Levels ..................................................................................................... 112 Toxic Noise Levels ....................................................................................................... 114 The Result .................................................................................................................... 115 The Solutions ............................................................................................................... 116 The Bottom Line ........................................................................................................... 117
Sound Science ................................................................................................................ 118 Obtaining Information .................................................................................................. 118 Sound Parameters ....................................................................................................... 120 Noise and Noise Abatement ........................................................................................ 120 Signal-to-Noise Ratio ................................................................................................... 122 Reverberation .............................................................................................................. 123
Ears and Hearing ............................................................................................................ 124 Anatomy of the Ear and “How It Works” ...................................................................... 125 Auditory Development ................................................................................................. 126
Hearing Evaluations ........................................................................................................ 129 Hearing Impairments ....................................................................................................... 132
Types and Causes of Hearing Loss (Etiology) ............................................................ 133 Disorders Reducing Sensitivity to Sound ................................................................. 133 Disorders of the Auditory Nervous System .............................................................. 137
Section B: Prevention ...................................................................................................... 139 Toxic Noise and Acoustic Trauma .................................................................................. 139
Continuous Noise ......................................................................................................... 139 Impulse Noise .............................................................................................................. 141
Recognizing Noise-Induced Hearing Loss (NIHL) .......................................................... 142 Classroom Noise ............................................................................................................. 143
Effect on Teachers ....................................................................................................... 143 Effect on Children ........................................................................................................ 143
Classroom Acoustics Standards ..................................................................................... 148 Putting Prevention into Practice ...................................................................................... 150
School Hearing Loss Prevention (Hearing Conservation) Programs ........................... 150 Involve the Students .................................................................................................... 152 Hearing Protection ....................................................................................................... 152 Teaching by Example .................................................................................................. 158 Reducing Noise in the Classroom ............................................................................... 158
Section C: Design Applications: Noise Problems and Solutions .................................... 161 New School and Classroom Construction ....................................................................... 161 Mechanical Equipment: HVAC (Heating, Ventilation, and Air Conditioning) .................. 162 Exterior Noise: Playgrounds, Street Traffic, Airplanes, and Trains ................................. 163 Hallway or Adjacent Space Noise ................................................................................... 163 Excessive Interior Classroom Noise (e.g., Computers and Other Equipment, Fans, Fish Tanks, People) ............................................................................................. 164 Long Reverberation Times (Echoes) ............................................................................... 165 Unacceptable Classroom Acoustics (No Available Engineering or Material Solutions) ..... 165 Summary ......................................................................................................................... 165 Appendix A: Frequently Asked Questions (FAQs) .......................................................... 166 Appendix B: Properties of Sound .................................................................................... 172 What Is Sound? ............................................................................................................... 172 Sound and Distance ........................................................................................................ 172 Appendix C: Resources .................................................................................................. 175 Web Sites, Organizations, Product Sources ................................................................... 175 References ...................................................................................................................... 180
Additional References ................................................................................................. 183
INTRODUCTION
Most of us do not think of sound (noise) as an ergonomic issue. Yet loud and distracting “toxic” noise is dangerous and can damage our ears. Even “safe” classroom sounds (noise) can hinder children from doing their jobs: listening, thinking, talking, creating, and learning (Shield and Dockrell, 2003a,b).
