Elenco Snap Circuits® Deluxe Sound & Light Combo - Manual (Page 18)

-17-
Sound in Our World
In stereo, sound is produced on several
speakers (or earphones) with varying
frequencies/loudness on each. This gives the
impression that the sound is coming from
different directions, and is more pleasing to
listen to. Mono sound is the same on all
speakers, and is easier to produce. Note that
a “stereo speaker” can be several speakers
(possibly of different sizes) in one package.
Your Snap Circuits ® speaker (SP2) is a mono
speaker. Surround sound is a technique for
placing several speakers (with different
sounds from each) around the listener, to
create a more interesting listening experience.
The loudness of sound waves is a measure of
the pressure level, and is expressed in
decibels (dB, a logarithmic scale). Long-term
exposure to loud sounds can lead to hearing
loss. Here are some examples of sound levels:
Sound waves travel very fast, but sometimes
you can perceive the effects of their speed.
Ever notice how sometimes you see lightning
before you hear the thunder? The reason is
because light travels at about 186,000 miles
per second, while sound travels at only about
1,100 feet per second in air. Sound can travel
through liquids and solids, but with increased
speed (the speed depends on the material’s
compressibility and density). Sound travels 4.3
times faster in water than in air; this difference
in speed confuses our ears, making it difficult
to perceive the direction of sound while
underwater.
A sonic boom is a shock wave that occurs
when an object travels through air at
supersonic speeds (faster than the speed of
sound). These sonic shock waves are similar
to how the bow of a boat produces waves in
the water. Sonic shock waves can carry a lot
of sound energy and can be very unpleasant
to hear, like an explosion. Aircraft can fly at
supersonic speeds, and the sonic boom
produced is so unpleasant that aircraft are
rarely permitted to fly at supersonic speeds
over populated areas.
Sound waves can reflect off walls and go
around corners, though their energy may be
reduced depending on the angle and the
roughness of the surface. Sometimes sound
waves can be channeled to focus in a certain
direction. As an example, get a long tube, like
the ones for wrapping paper. Use one of the
projects that make a continuous tone, such as
projects 6 or 92. Hold one end of the tube next
to the speaker (use the yellow side with the
grating) and the other end near your ear, then
remove the tube and compare the sound
volume at the same distance from the speaker.
The long tube should make the sound
reaching your ear louder, because sound
waves reflect off the tube walls and stay
concentrated, instead of spreading out across
the room.
Sound Source Level
Threshold of pain 130dB
Chain saw 110dB
Normal conversation 50dB
Calm breathing 10dB
Hearing threshold 0dB
Surround sound
Sonic boom
It’s hard to perceive
sound direction
underwater.
Placing a long tube next to
the speaker keeps its sound
waves together longer.
Sound waves
Long tube
Speaker
SCC-350_Manual_Part_A.qxp 7/25/14 2:39 PM Page 18