BACKGROUND:
Most information comes to us in some
form of waves. It is through wave motion that light comes to our eyes
and sound comes to our ears. In our built environment, humans capture
and use the power of sound and light to infiltrate every aspect of our
lives. The richness of sounds and sights are all around, and they would
be difficult for many of us to live without. Ask students to imagine
being a blind or deaf person. These next units act as a vehicle to
discuss how we use sound (physical waves) and light (electromagnetic
waves) in our society.
Wherever we are, we are surrounded by
sound. It might be the pleasant sounds of a breeze or the intense sounds
of a jet engine. The loudest sounds we can tolerate have intensities a
million times greater than the faintest sounds we hear. The relative
loudness of a sound is measured in decibels, abbreviated db. The decibel
(db) was named in honor of Alexander Graham Bell. Some common sounds and
their noise levels are:
| jet airplane, 100 feet away |
140 db |
|
air raid siren, nearby |
125 db |
|
rock music, amplified |
120 db |
|
riveter |
95 db |
|
busy street traffic |
70 db |
|
conversation in home |
65 db |
|
quiet radio in home |
40 db |
|
whisper |
10 db |
|
rustle of leaves |
20 db |
|
threshold of hearing |
0 db |
PROCEDURE:
- Scientists have learned that noise
can be harmful to humans. Noise changes our moods, prevents us from
concentrating, and may even reduce our ability to learn. Very loud noise
can damage our bodies.
- The worksheet has students look at
different sounds during a day. Using the chart, they must determine the
approximate decibels of the sound. For example: A student worked by a
construction job. It was noisy. The noise level was somewhere between a
riveter (95 db) and a busy street (70 db). The student would write 85
db. If a person is exposed to noise over the 95 decibel range for a long
period of time, their hearing may be impaired. The ear drum which picks
up the sound, can actually be damaged.
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