Why Do Sound Waves Cancel Each Other Out?

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SUMMARY

The discussion centers on the principles of sound wave interference, specifically destructive interference. The user calculates the time for a sound wave to travel 1.7 meters, determining it takes 0.005 seconds. They correctly identify that for destructive interference to occur, the distance must be an odd multiple of the half-wavelength, clarifying their misunderstanding regarding the frequency calculations, which could yield multiple frequencies (200Hz, 300Hz, or 400Hz) if not correctly applied.

PREREQUISITES
  • Understanding of sound wave properties, including frequency and wavelength.
  • Basic knowledge of wave interference concepts, specifically constructive and destructive interference.
  • Familiarity with the speed of sound in air (approximately 340 m/s).
  • Ability to perform calculations involving wave periods and frequencies.
NEXT STEPS
  • Study the principles of wave interference in detail, focusing on destructive interference.
  • Learn how to calculate wavelength and frequency relationships in sound waves.
  • Explore the effects of medium on sound wave propagation and speed.
  • Investigate real-world applications of sound wave interference, such as noise-canceling technology.
USEFUL FOR

Students in physics, acoustics researchers, audio engineers, and anyone interested in the behavior of sound waves and their applications in technology.

Spyder22
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I'm confused by this problem: http://myspace.homelinux.com:32123/sound.jpg
Can someone explain the solution and what's wrong with my reasoning?
It takes 1.7/340 = .005 sec for the wave to travel the 1.7m. So for the waves to cancel woudn't .005 = T * 1/2 * n (where T is the period of the wave and n is an integer)? Since T= 1/f, we have f = 100n. But then f could be 200hz, 300hz, or 400hz, so that must be wrong... :frown:
 
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For destructive interference, the distance must be an odd multiple of the half-wavelength. If it were an even multiple, that would be constructive interference.
 
oh wow duh that was obvious :blushing: thanks!
 

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