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Why can two steady notes seem to pulse?

Play two steady tones with slightly different frequencies and their combination can grow louder and softer. As the waves move into and out of step, they reinforce and weaken one another. These acoustic beats are a pattern in the combined sound, even though neither source is deliberately pulsing.

3–5 min

Questions you could explore

  • How does the difference between the frequencies affect the pulse rate?

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Why metal can feel colder than wood

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3–5 min

How can a ship made of steel float?

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