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Sound Notes

Learn about the properties and waves of sound, the speed of sound in different materials, and how to verify frequency using a tuning fork. Discover the concepts of resonance, closed-ended and open-ended tubes, and the decibel scale for measuring sound. Explore the range of audibility of the human ear, the phenomenon of beats, and the functioning of the ear's different parts. Lastly, delve into the Doppler effect and the impact of sound in music.

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Sound Notes

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  1. Sound Notes Chatfield Senior High Department of Physics

  2. Sound is a Wave • It is a longitudinal (1-D) wave

  3. Properties of Sound • Transmission-sound goes through a material Reflection- waves bounce off at the same angle it was received Absorption- waves are blocked by a substance (opposite of transmission)

  4. Transmission in space? Sound requires a medium to travel

  5. Speed of Sound • It is variable based upon temperature and density of the material • Approximate values of speed of sound • Air (00-) 330 m/s • Air (25o) 343 m/s • Water-1440 m/s • Glass-4550 m/s • Iron and Steel- 5000m/s

  6. Lab 1- Verifying frequency of a tuning fork • Determine period of wave by averaging 10 wavefronts as below and then use f=1/T to verify frequency

  7. FFT Curve

  8. Lab 2-Sound through echo • Find distance of the tube and double it (why?) • Use v=d/t to determine the speed of sound in air.

  9. Lab 3-Finding Resonance of Tube • Find frequency where sound rings out • The sound is reflecting off the water and therefore creates a closed ended tube • The l is basically a quarter of a wavelength (why?)

  10. Resonance in Sound • Wavelengths that have the same amplitude and frequency that result in an increase of amplitude

  11. Closed Ended Tube (Pipe organ)

  12. Open-Ended Tubes and Strings(Organ / Guitar String) (1/2 l)

  13. The decibel • A logarithmic scale that shows the loudness of sound L=10 A A= log L • Table of values Threshold of hearing- 0 dB Whisper-20 dB Library-40 dB Refrigerator-45 dB Restaurant- 50 dB Ordinary Conversation-65 dB Busy Traffic- 70 dB Screaming Child- 90 dB iPod at Maximum Volume-108 dB CSH Fire Alarm-115 dB Threshold of Pain-120 dB Jet Airplane-140 dB

  14. Frequencies of Sound • The human ear hears sound from the range from 20-20000 Hz • We hear sounds the best from 1000-5000 Hz

  15. Frequencies of Music

  16. Range of Audibility of the Human Ear

  17. Ultrasound(Frequencies above human hearing)

  18. Beats • Two waves constructively interfering whose frequencies are above or below each other

  19. The Ear

  20. Function of the Ear’s parts • Outer ear-pinna-collects sound • Middle ear-transmits vibrations to the inner ear • Inner ear-fluid transmitted to hair cells that have nerve endings (also used for balance)

  21. Doppler Effect • When an object is moving toward the observer the pitch is higher • When an object is moving away from the observer the pitch is lower

  22. Sonic Boom

  23. Sound and Music • Most pure…the Blue Man Group

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