Elenco Snap Circuits® Deluxe Sound & Light Combo - Manual (Page 20)

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Sound in Our World
Electronically we amplify sound by converting
the sound waves into an electrical signal,
amplify the electrical signal, and then convert
that back to sound waves.
There are many other applications for sound
waves. Here are some examples:
In SONAR (short for SOund Navigation And
Ranging), sound waves are sent out underwater
at various frequencies and the echoes are
measured; the distance to any objects can be
determined using the time for the echoes to
arrive, and the speed of sound. SONAR is used
for navigating around underwater obstacles and
for detecting other ships, especially submarines.
SONAR is also used by the fishing industry to
help find and harvest fish. Sound waves can
also be used to determine the depth of an oil
well. RADAR (RAdio Detection And Ranging) is
similar to SONAR but uses radio waves instead
of sound waves.
Ultrasound waves are above 20 kHz, beyond
the range of human hearing. Bats use
ultrasound waves to effectively “see” in the
dark. Ultrasound waves are also used in
medical imaging, to create pictures of muscles
and organs in the human body. Ultrasound
waves are sometimes used in cleaning items
like jewelry.
Ultrasonic welding is used in industry to bond
materials (usually plastics) together using high
frequency sound waves. The energy of the
sound waves is concentrated at the points to
be bonded, and basically melts the material at
the contact points. This can create a strong
bond, without using glue or nails. Ultrasonic
welding has been used to bond the bottoms of
Snap Circuits ® parts in the past, and might still
be used for the speaker (SP2) and
microphone (X1).
Earthquakes are compression waves, similar
to sound waves but with enormous power.
Using triangulation from several measurement
points, and knowing how fast these waves can
travel across the earth’s surface, scientists can
determine where the earthquake began (called
the epicenter).
Music
The subject of music is one where the worlds
of art and science come together.
Unfortunately, the artistic/musician field works
with qualities that depend on our feelings and
so are difficult to express using numbers while
science/engineering works with the opposite -
clearly defined, measurable qualities. As a
result, some of the terms used may seem
confusing at first, but you will get used to them.
Music is when vibrations (creating sound
waves) occur in an orderly and controlled
manner forming a pattern with their energy
concentrated at specific frequencies, usually
pleasant to listen to. Noise is when the
vibrations occur in an irregular manner with
their energy spread across a wide range of
frequencies, usually annoying to hear (static
on a radio is a good example). Notice how
some people refer to music that they don’t like
as noise. In electrical systems, noise is
undesired interference that can obscure the
signal of interest.
Another way to think of this is that the ear tries
to estimate the next sounds it will hear. Music
with a beat, a rhythm, and familiar instruments
can be thought of as very predictable, so we
find it pleasant to listen to. Notice also that we
always prefer familiar songs to music that we
are hearing for the first time. Sudden, loud,
unpredictable sounds (such as gunfire, a glass
breaking, or an alarm clock) are very
Cone
Ear Trumpet Stethoscope
Horn
Anvil or jig
Plastic
parts
Phase 1 Phase 2 Phase 3
Pressure is applied
by the horn.
The horn vibrates
the plastic parts
very quickly.
The plastic parts
melt together from
the friction created.
SONAR
Ultrasonic welding
Ultrasound photo of a heart (echocardiogram)
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