1. Properties of Sound
EQ: How does intensity, loudness,
frequency and pitch affect sound
waves?
2. Vocabulary
• Intensity – the amount of energy an sound
wave carries per second through a unit
area. Measured in watts per meter
squared. W/m²
– Example – When a sound wave carries a
large amount of energy, the molecules of the
medium move a greater distance as the wave
pass by, and the sound has a greater
amplitude EQ: How does intensity, loudness,
frequency and pitch affect sound
waves?
3. Vocabulary
• Loudness – sound level, describes what
you actually hear. A sound wave of
greater intensity sounds louder
• Decibels (dB) – measures loudness. A
sound you can barely hear is 0 dB. 100dB
can damage your ears.
EQ: How does intensity, loudness,
frequency and pitch affect sound waves?
5. Intensity determines loudness.
A sound wave with a lower amplitude and energy
is perceived as a softer sound.
EQ: How does intensity, loudness,
frequency and pitch affect sound
waves?
6. Vocabulary
Frequency – the number of vibrations that occur
per second in a sound wave. Measured in
Hertz. A frequency of 50Hz means 50 vibrations
per second.
– We hear sounds with frequencies that are between
20Hz and 20,000Hz
Ultrasound – sound waves with frequencies
above the normal range of hearing
Infrasound – sound waves with frequencies below
the human range of hearing EQ: How does intensity,
loudness, frequency and pitch
affect sound waves?
7. Vocabulary
• Pitch – a description of how high or how
low a sound seems to a person.
• Pitch depends on the frequency of a
sound wave
– High frequency means high pitch
– Low frequency means low pitch
EQ: How does intensity, loudness, frequency
and pitch affect sound waves?
8. Frequency determines pitch.
A sound wave with a higher frequency and shorter
wavelength is perceived to have a higher pitch.
A sound wave with a lower frequency and longer
wavelength is perceived to have a lower pitch.
EQ: How does
intensity,
loudness,
frequency and
pitch affect
sound waves?
9. Piano Example of Pitch
Tension - A tighter string produces a higher
frequency. Therefore you hear the sound
at a higher pitch.
Length of the string - right side of the piano
has higher pitch, shorter string. Left side
of piano has lower pitch, longer string
Thickness of a string – thicker means lower
pitch EQ: How does intensity, loudness, frequency and
pitch affect sound waves?
10. Vocabulary
• Resonance – when the frequency of the
sound wave exactly matches the
frequency of an object
EQ: How does intensity, loudness,
frequency and pitch affect sound waves?
11. Doppler Effect
The apparent change in frequency as a
wave source moves in relation to the
listener
EQ: How does
intensity,
loudness,
frequency and
pitch affect
sound waves?
12. Doppler Effect
• As a sound source moves toward the
listener, the waves reach the listener with
a higher frequency. The pitch appears to
increase because of the Doppler effect
EQ: How does
intensity, loudness,
frequency and pitch
affect sound
waves?
13. Class Work and Homework
Fill In
• What did I learn
• Confused
• Say
• Read pages O 46 – O 51.
• Questions 1-6, p. O 51
• 2-2 Worksheet
EQ: How does
intensity, loudness,
frequency and pitch
affect sound waves?
