TRY IT AT HOME OR SCHOOL

The secret behind Voice Over is the parabola: a curve with special mathematical properties. No matter where a sound wave (like your whisper) hits that curve, the dish’s slope will reflect it out to one spot called the “focus” or “focal point.” Then those sound waves reflect off the other dish’s curved surface and out to a focal point near the listener’s ear. The multiple reflections also amplify the sound.


I SPY…parabolic reflectors!
Can you spy parabolic reflectors at work around you? Some hints to help you spot them:

  • You might spy them used in architecture where sound needs to be amplified or controlled (ex: band shell or amphitheater)

  • You might spy them paired with a microphone; they’re especially handy for recording sound from a distance (ex: sounds from a football field)

  • Parabolic reflectors are also used to focus and amplify light waves (ex: headlights, flashlights, solar cookers) and electromagnetic radio waves (ex: satellite dishes)

  • You may even spy them in nature! Some owl species have “facial dishes” that help to reflect and amplify sounds to ear openings beneath their feathers. Male moose may get a hearing boost from their massive curved antlers.


ACTIVITIES:
Explorer Zone: Sound of Silos

VIDEO: Echoes and reverberations

VIDEO: Reflection of sound


CAREER CONNECTION:
“I loved music and wanted to be a radio DJ. Then one of my professors said, ‘What about making the records?’” – Jeff Byrd, Audio Engineer for Austin City Limits

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