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H4-18. Lissajous Figures With Sound
Purpose
To demonstrate the relation between "consonance" (musical intervals) and frequency ratios.
Equipment
Two oscillators with loudspeakers and oscilloscope with scope/TV cart.
Images
Description
Two identical oscillator/loudspeaker setups are sounded and simultaneously input into the two axes of an oscilloscope to produce a Lissajous figure. Two pitches which are related by simple rational whole numbers such as 3:2 or 5:4 are musical intervals and produce stationary figures. Beats between two close frequencies are also visibly evident by this technique. Try two close frequencies and two related by a small whole number interval for contrast. Let your students judge their consonance.
References
(PIRA unavailable.)
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See pagesh1. nature of sound
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See pagesh2. wave properties of sound
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See pagesh3. standing sound waves
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See pagesh4. music
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See pagesh5. the ear
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See pagesh6. the voice
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See pagesh1. nature of sound
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See pagesh2. wave properties of sound
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See pagesh3. standing sound waves
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See pagesh4. music
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See pagesh5. the ear
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See pagesh6. the voice