Echo Facts



  • An echo is the reflection of a sound. You hear it a little while after the sound is made.
  • You can only hear an echo if it comes back more than 0.1 seconds after the original sound.
  • Sound travels 34 m in 0.1 seconds, so you only hear echoes from surfaces that are at least 17 m away.
  • Smooth hard surfaces give the best echoes because they break up the sound waves the least.
  • Acoustics is the study of how sounds are created, transmitted and received.
  • The acoustics of a space is how sound is heard and how it echoes around that space, whether it is a room or a large concert hall. Electricity, magnetism and radiation
  • When concert halls are designed, the idea is not to eliminate echoes altogether but to use them effectively.
  • A hall with too much echo sounds harsh and unclear, as echoing sounds interfere with new sounds.
  • A hall without echoes sounds muffled and lifeless.
  • Even in the best concert halls, the music can be heard fading after the orchestra stops playing. This delay is called the reverberation time. Concert halls typically have a reverberation time of two seconds. A cathedral may reverberate for up to eight seconds, giving a more mellow, but less clear, sound.
  • Sydney Opera House in Australia is famous for its stunning design, but some orchestras have complained about its acoustics.