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Properties of Sound. EQ: How does intensity, loudness, frequency and pitch affect sound waves?. Vocabulary. Intensity – the amount of energy an sound wave carries per second through a unit area. Measured in watts per meter squared. W/m ²
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Properties of Sound EQ: How does intensity, loudness, frequency and pitch affect sound waves?
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?
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?
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? SECTION OUTLINE
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?
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?
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?
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.
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?
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?
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?
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
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?
