How do sound wave summate or negate?

Sound wave do not summate or negate.........

The reason is sound wave when passing by each other is subject to wave phase. When in sync (in-phase) the product equals a summation. 

When one of the wave is out of phase, the product equals null.

If they don't meet, nothing happens :)

Since sound in real world are traveling in random-like manner, (remember the video?) therefore they will rarely fully summate or negate. Compromise will be made for the sake of human kinds :)

It is to be stressed that low frequency has large wavelengths and hence easily match able by angle and distance, therefore low frequency suffer negation more than high frequency.

This is why the final graph in Reality Bites looks the way it looks. The lower the frequency the easier to cancel itself out........

Please be informed that this is not the end of the story, please do not make the conclusion alone.




  1. Introduction to Acoustics
  2. What are acoustics?
  3. How is sound created?
  4. What are the definitions of sound?
  5. How do sound travel?
  6. What is wavelength?
  7. Is sound a science?
  8. How do sound disperse?
  9. How long for sound to reach us?
  10. Do sound reflect?
  11. How do sound reflect?
  12. Do room volume affects sound?
  13. Do room shape affects sound?
  14. What is sound absorption?
  15. What is sound proof?
  16. How do sound wave summate or negate?
  17. Why do we need to know all these?



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