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Theatre Acoustics

Geometry & Trigonometry

Calculate direct and reflected sound path lengths in a theatre to find which seats hear a clean sound and which hear an echo.

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Introduction

Sound reaching a seat in a theatre travels by more than one path: directly from the stage, and reflected off walls, ceiling and floor. Each path has a different length, so the reflected sound arrives slightly after the direct sound. If that delay is long enough, the audience hears a distinct echo instead of a single blended sound. This exploration asks you to calculate path lengths and delays for real seats in a real auditorium, and to find where the best and worst seats are.

Guiding Questions
  • In a theatre, sound reaches you directly and from reflections. Which paths matter most for what you hear?
  • Pick a seat and compute the direct and first-reflection path lengths. What is the delay between them?
  • Where are the best and worst seats by this measure? Map the delay across the hall.
  • Curved ceilings can focus sound. Model a curved reflector and find its hot spots.
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Key Mathematical Concepts
Geometry Physics Acoustics Sound Waves
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