Chapter 3 Lesson 1

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Chapter 3 Lesson 1
The Nature of Sound
Reading Focus- How can you describe sound waves?
Vibrations- Back-and-forth movements of matter.
Air carries vibrations to your eardrums and
causes them to vibrate.
Vibrations produce nerve impulses that are
carried to brain.
Nerve impulses interpreted as sounds in brain.
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Sound Waves notes
Sound- Form of energy that you can hear and that
travels through matter as waves.
Compression- Region of a sound wave where the
particles have been pushed closer together. Air
pressure higher.
Crest- High point of wave. Represents the
compressions.
Rarefaction- Region of wave where there are fewer
particles than normal. Air pressure lower.
Troughs- Low point of wave. Represents the
rarefactions.
As sound wave travels, the particles that carry
the wave do not travel along with it.
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Measuring Sound Waves notes
Wavelength- Distance from one compression, or
trough, to the next.
Frequency- Number of complete waves produced in a
unit of time, such as a second.
High sounds have high frequencies and low sounds
have low frequencies.
Amplitude- distance from rest to a crest or rest
to a trough. Measures amount of energy in a sound
wave. Large sound has large amplitude, soft
sound has small amplitude.
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Quality of Sound- Timbre notes
Most sounds are complex. Musical instrument
sounds made up of a basic tone and an overtone.
Overtone- Softer, higher tones that are mixed
with basic tones.
Timbre- The special sound produced by a musical
instrument.
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Noise notes
Pleasant sounds such as music have waves that are
smooth and repeating.
Unpleasant sounds, or noises, have irregular
sound waves.