Course:PHYS341/2018/Calendar/Lecture05

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Phys341 Lecture 05: Summary and web references

2018.01.12

Textbook: Sections 5.1-5.6

  1. Sound waves
  2. Transmission vs. radiation
  3. Sound Waves in 3D https://www.youtube.com/watch?v=zwno1w_F3TQ
  4. Speed of sound in air
  5. Speed of sound in solids
  6. Sound waves in liquids https://en.wikipedia.org/wiki/Hot_chocolate_effect
  7. A hard demonstration to do in class... https://www.youtube.com/watch?v=q9ezMbDpIHI
  8. Change of medium, impedance
  9. Reflection of sound
  10. Refraction of sound http://acousticstoday.org/wp-content/uploads/2015/06/Sound-Propagation-in-the-Atmospheric-Boundary-Layer-D.-Keith-Wilson-Chris-L.-Pettit-and-Vladimir-E.-Ostashev.pdf (very technical)
  11. Sound in a bell jar https://www.youtube.com/watch?v=hIOqX4uJtYY
  12. So this is all rubbish...
  13. Impedance matching
    • “Impedance matching” is the physics term for designing an interface to optimize power transfer across it, or to suppress a standing wave.
    • Soundboard of a string instrument optimizes power transfer from strings to radiated sound
    • Bell of a brass instrument: the gradual change of acoustic conditions from inside the bore to the open air prevents high frequency standing waves, thus mellowing the sound
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