Answers to the I Can Statements for Sound and Waves
Goal A
A1. Waves are created by vibrations. In a wave the energy moves forward and the
particles of the medium move up and down or back and forth.
A2. Crest – the top of a transverse wave, Trough – the bottom of a transverse wave,
Resting Position – the original position of the medium before the wave energy passed
through it. Wavelength – the distance between two crests, two troughs, or two of the
closest identical points on a wave. Amplitude – the distance the particles are moved from
their resting position
A3. Compression – where the particles are closely packed together, rarefaction – where
the particles are spread out, wavelength – the distance between two compressions or two
rarefactions.
A4. In a longitudinal wave (compression wave), the particles move back and forth
parallel to the direction of the energy movement. Examples – sound, p waves in
earthquakes,
In a transverse wave the particles move perpendicularly (up and down) to the direction of
energy movement. Examples – light waves, all radiation waves, s-waves in an
earthquake
A5. The speed of a wave is affected by the density of the medium. Most waves travel
slowest through gases and fastest through solids.
A6. Frequency is the number of wavelengths that pass one point in a second. It is
measured in Hertz (Hz). Pitch is the relative highness or lowness of a sound. The higher
the frequency, the higher the pitch. It is a direct relationship.
A high pitch string will be short, thin, and tight. A low pitch string will be long, loose,
and thick.
A7. Amplitude is the distance a particle is moved from its resting position by a wave. As
the amplitude increases, the volume (loudness) increases. It is a direct relationship.
A8. Hearing: The pinna collects the sound waves and funnels them into the ear canal.
The ear canal takes the waves to the ear drum. The eardrum vibrates and moves the
hammer, anvil, and stirrup. The stirrup pulls on the oval window of the cochlea creating
pulses in the fluid. The fluid causes the hairs to move which creates an electrical current
which is collected by the auditory nerve. The auditory nerve is connected to the brain
and the brain interprets the sound.
A9. Pinna – outer ear – collects sound waves
Ear Canal – funnels the waves to the Eardrum
Eardrum – vibrates in response to the sound waves
Hammer, anvil, and stirrup – middle ear carries the vibrations to the inner ear.
Eustachian Tube – connects to the oral cavity and allows you to adjust to different air
pressures
Cochlea – inner ear that changes vibrations into electrical impulses
Semi-circular canals – helps you keep your sense of balance (what is up and what is
down) (Dizziness is created here)
Auditory Nerve – carries the impulses to the brain for interpretation
A10. Ear infections affect your hearing by filling your middle ear with a thick fluid / pus
which makes it hard to the hammer, anvil, and stirrup to vibrate. As you age, your higher
frequency hairs in your inner ear (cochlea) begin to fall out and so you no longer can hear
certain frequencies. In addition, your eardrum may be damaged and less able to vibrate
so you cannot distinguish sounds. Sound pollution can hurt your eardrums by causing
them to rupture and your cochlea by causing the hairs to die.
A11. Vocal cords are folds of tissue in your larynx (voice box) that vibrate as air passes
through them to produce sound.
A12. Laryngitis – the vocal folds / cords are swollen and cannot vibrate well. Polyps are
growths on your vocal cords / folds that make your voice sound different. Overuse of
your vocal cords can cause polyps or a hemorrhage when a blood vessel pops and your
vocal cords will not work correctly.