Music

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Music
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Standing Waves

• At the right frequencies a constrained wave will
  produce a standing wave
• Standing waves appear stationary
• Result of constructive and destructive
  interference
• Have nodes and antinodes

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Nodes and Antinodes

• Nodes
• Wave doesnt move
• Destructive interference
• Antinodes
• Wave moves
• Constructive interference

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Harmonics

• Fundamental frequency
• Two nodes
• Half a wavelength in between ends
• Pattern of standing waves is called the harmonic
  series

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Harmonic Series

• String or pipe open at both ends
• n 1, 2, 3, 4,
• String both ends are nodes
• Open pipe both ends are antinodes

• Pipe closed at one end
• n 1, 3, 5,
• Pipe open at one end closed side in node, open
  side in antinode

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Instruments

• Vibrating strings
• Violins, guitars, bass etc.
• Piano, harpsichord
• Pipe open at both ends
• Flute
• Pipe open at one end and closed at the other
• Saxophone, clarinet, trumpet, trombone, etc.

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Timbre

• Different instruments playing the same note sound
  different because of harmonics
• The intensity of the harmonics varies between
  instruments
• Changes the timbre, or sound quality of each
  instrument

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Beats

• When two waves of different frequencies interfere
  the result is a complex interference pattern
• The result is areas of constructive interference
  and areas of destructive interference
• This amplitude variation are the beats
• And the frequency with which they vary is the
  beat frequency
• Beat frequency is the difference between the
  original two waves frequency

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Consonance and Dissonance

• Depends on the frequency difference between two
  tones
• Varies between cultures and eras

• Consonance
• Octave
• Perfect fourth
• Perfect fifth
• Dissonance
• Minor second
• Major seventh