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?

4. Intensity determines loudness.
A sound wave with a higher amplitude and energy
is perceived as a louder sound.
EQ: How does intensity, loudness, frequency and pitch affect sound waves?
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OUTLINE

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 lower frequency and longer
wavelength is perceived to have a lower pitch.
EQ: How does intensity, loudness, frequency and pitch affect sound waves?
A sound wave with a higher frequency and shorter
wavelength is perceived to have a higher pitch.

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. EQ: How does intensity, loudness, frequency and pitch affect sound waves?
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

13. Class Work and Homework
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What did I learn
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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?