PH 105


Winter 2004-2005

No. Day Label Time Title Description             End of List
1 Dec. 3 I, #4 5:12 Transverse Standing Waves Shows the vibrational modes of a string.
2 Dec. 6 I, #5 3:45 Longitudinal Waves in a Helical Spring (a) Shows how the leading edge of a pulse compresses the medium and the trailing edges expands it.  (b) Each coil of the spring undergoes SHM.  (c) Two pulses coming from opposite directions pass through each other, momentarily interfering constructively and destructively.
3 Dec. 6 I, #6 5:20 Longitudinal Standing Waves Continuous longitudinal waves are produced by a variable-frequency mechanical driver and are reflected off of the fixed end.  At certain frequencies, the interference produces a standing wave with nodes and antinodes, as illustrated with a strobe (blinking light).  Model: The spring represents a standing sound wave in air and the coils represent air molecules.
4 Dec. 6 II, #1 3:51 Sources and Propagation of Sound A vibrating tuning fork is examined with a strobe, computer animation, speaker and a "sensitive flame".
5 Dec. 6 Clint Sprott Demos   Sound in Air, Helium, Sulfur Hexafluoride 1. Ringing a bell in a vacuum jar.
2. Inhale helium - higher pitch - lower density - higher velocity
  Inhale sulfur hexafluoride - lower pitch - higher density - lower velocity
6 Dec. 6 I, #7 3:32 Reflection and Refraction Shows the reflection and refraction of waves on the surface of a water tank.
 7 Dec. 8 II, #5 2:52 Sound Divided into Two Paths of Differing Length One sound source is split into two paths of differing lengths. Then the sounds paths are brought together and interfere.
 8 Dec. 8 II, #6 3:50 Beat Phenomena A beat pattern is produced (a) with two tuning forks of slightly different frequency and (b) with two electronically produced sound waves.
 9 Dec. 8 I, #8a 2:25 Diffraction of Waves This shows how waves on a ripple tank take a curved path around a barrier. (stop at interference with two bobbers).
10 Dec. 8 II, #7 2:45 Bending of Sound Waves around an Obstacle This illustrates how sound from a speakers bends around and obstacle and is received by a microphone.
11 Dec. 8 I, #8b 2:20 Interference Two sources of waves on a ripple tank travel outward, overlap and interfere with another, shows places of constructive and destructive interference.
12 Dec. 10 II, #8 1:58 Doppler Effect Shows the effect using a rotating whistle.  Includes animation.
13 Dec. 10 III, #6 4:06 Vibrations of a Guitar String Examines the harmonic composition (collection of standing waves) of a vibrating guitar string.
14 Dec. 13 III, #1 4:45 Resonating Air Column: Cork Dust Standing sound waves are revealed by cork dust in a glass tube. The speaker at one end is driven by a variable frequency generator. At resonance, the cork dust is stirred up showing the location of the vibration antinodes. Where the cork dust is not moving, there are vibration nodes.
15 Dec. 13 III, #2 4:43 Resonance: Illuminating Gas in a Flame Tube The height of the flames shows the location of the pressure antinodes (max. height). Note that this is effectively a tube that is closed at both ends.
16 Dec. 15 Robert Greenler 10:00 Acoustics Demos - Part 1 1. whistle and a rubber tube, 2. build-a-sound toy, 3. long and short recorders, 4. clarinet
17 Jan. 3 " 5:50 Acoustics Demos - Part 2 1. resonators - bottles, 2. Pepsi phone, 3. Hummer toy
18 Jan. 3 "   Acoustics Demos - Part 3 1. vibrating rods, 2. xylophone, 3. Nailolian (this is a palindrome)
19 Jan. 3 III, #4 3:22 Chladni Plate This shows the nodes and loops of vibrating plates.
20 Jan. 5 III, #5 3:32 Resonant Modes of a Vibrating Bell using Holography Illustrates the various modes (standing wave patterns) of a resonating handbell.  The modes are visualized through a technique in which laser light from the vibrating bell interferes with light from its holographic image.
21 Jan. 5 Robert Greenler 6:00 Glass Harmonica Wine glasses are made to vibrate by rubbing a moist finger on their rim.  Fine tuning is achieved by adding water.
22 Jan. 14 III, #7 4:14 Fourier Analysis - Sound of a Trombone The complex sound produced by a trombone is analyzed into its harmonic components.  Then this sound is reconstructed using these same sine waves.
23 Jan. 17 From "Ask This Old House",
PBS - May 10, 2003.
5:50 Measurements of Noise Levels in the Wood Shop Shows a research audiologist, Dr. Mark Stephenson of the National Institute for Occupational Safety and Health, measuring the noise level of a number of things that are very noisy in the wood shop and around the yard.  He is wearing a special headset that filters out loud noises while permitting regular conversation.
24 Jan. 24 III, #8 2:51 Audible and Ultrasound Waves A high frequency speaker and a piezoelectric crystal are used to demonstrate sound waves from 10,000 Hz to 200,000 Hz.
25 Jan. 28 Narrated by Tony Randall 15:00 Tuning of Meyerhoff Hall Shows the design, construction, testing and enjoyment of a concert hall that was built in Baltimore.  Take notes on the 8 design goals and techniques.
26 Feb. 16 NOVA
Nov., 1990
55:00 What is Music? Topics include:  1. new bells (see p. 304), 2. building blocks of musical tones, 3. Wendy Carlos - synthesizers (Switched-On Bach - 1968), 4. new violins, 5. electronic baton, 6. playing a piano musically, 7. processing sound in the brain, 8. the seven emotions in music, 9. summary by 8 people.