1. Vibrations and Waves Amplitude – maximum displacement from equilibrium
Frequency – number of cycles or vibrations per unit of time
Period – the time it takes to execute a complete cycle of motion

2. Fundamental frequency
A guitar string = ½ a wavelength L
Vibration is greatest at the antinode
So a wavelength is twice the string length... λ = 2L
Velocity = frequency x wavelength, or v = fλ or f = v/t
now substitute value for f f 1 = v/λ = v/2L
Frequency is inversely proportional to wavelength
Pendulum Lab:

3. Longitudinal Sound wave
Or Compression Wave
Sound wave - visual
Visual soundwave
Decibles:
Wave in tub

4. Harmonics are the integral multiples of the fundamental frequency
Harmonic series of standing waves on a vibrating string:
frequency = harmonic number X speed of waves
(2)(length of string)
or f n = n x v / 2L

5. Harmonic series Standing waves in an air column:
If both ends are open, all harmonics are present. Antinodes exist at the end of the tube (the opposite of strings!)
Distance between nodes = ½ wavelength
or...
d = ½ λ
This is the same as a vibrating string... fn = v/2L

6. Harmonic series Standing waves in an air column:
If one end is closed, only odd harmonics are present. The closed end is a node and the open end is an antinodes.
Fundamental frequency: f 1 = v/λ = v/4L
Third harmonic has ¾ of a wavelength so λ = 4/3 L
f 3 = v = 3v = 3v = 3f1
λ /3L L
fn = n x v/4L v = speed of sound in the tube
n = harmonic number
L = length of tube

7. Fundamental frequency is the lowest possible f of a standing wave

8. Decibels – unit measuring the intensity of sound
Exponential scale (logarithm)
0 dB = smallest audible sound
10 dB = threshold of good hearing
20 dB = leaves rustling, ticking of watch
30 dB = whisper
40 dB = 104 quiet library
50 dB = 105 moderate rainfall
60 dB = normal voice; dishwasher
70 dB = 107 busy street traffic
80 dB = 108 vacuum cleaner; alarm clock
90 dB = 109 lawnmower; hair dryer, blender
100 dB = mp3 player at full volume; lawn mower
110 dB = 1011 front row at a rock concert; car horn
120 dB = 1012 police siren
130 dB = 1013 threshold of pain; jackhammer
140 dB = 1014 military jet takeoff; gunshot; fireworks
150 dB = instant perforation of the eardrum
The amount of energy transported through a medium is called the intensity of the wave.
Intensity = Power/area
Unit = watts/meter2
Amplitude – measureable
Loudness – human perception, duration, frequency

9. Any sound above 85 dB can cause hearing loss.
Related both to the power as well as length of exposure.
Stereo cilia (really microvilli, contain actin filaments)
Located on the basilar membrane in one of
the three compartments of the Cochlea.
(16,000-20,000 of the hair-like cells)
When broken, the signal is constantly sent to the brain (tinnitus)

10. Sound
NPR – The Sound Book (“Sound Intriguing: The World’s Most Interesting Noises”)
The coolest things sound waves can do
William Tell Overture