Review: Musical Instruments and Music

    1. Musical Instruments
      • Instrument Groups are: String, Keyboard, Woodwind, Brass and Percussion instruments
      • All instruments have primary resonators and secondary resonators and often resonating cavities.
      • What determines the sounds of the different instrument groups?
    2. String vibrations, Pipes
      • The speed of sound is constant, so the wavelength is inversely proportional to the frequency:tex2html_wrap_inline41
      • If a string that sounds a certain note is shortened by 1/2, then an octave higher will be heard
      • If a string is shortened to 2/3 of its length, then a fifth higher will be heard
      • If a string is shortened to 1/3 of its length, then a octave above the fifth will be heard
      • A shortened pipe will behave in a similar manner; if shortened (usually by opening a hole) by 2/3 of its length, a fifth higher will be heard.
    3. Harmonics
      • A string can vibrate in any of the usual standing wave patterns where 2L = n and n can be 1, or 2, or 3, etc.
      • The harmonics are heard from the number of different ways that a string can vibrate The lowest harmonic is the fundamental, where one-half wavelength stretches across the string length L
      • The second harmonics fits one full wavelength across L; each half of L vibrates independently, as if L were split into two parts. The second harmonics sounds one octave higher, just like the string that was shortened by 1/2
    4. Music Intervals
      • The higher the pitch, the larger the frequency
      • The frequency change across one octave is a factor of 2
      • The frequency change from the fundamental to the fifth is a factor of 3/2
      • The frequency change from the fundamental to the third is a factor of 5/4
      • A major chord is a fundamental, third, and fifth sounded simultaneously
    5. The musical keys
      • We can use the piano key called middle C as a reference note; it has a frequency of 261.6 Hz
      • The note 'A' above middle C is known as concert A; it has a frequency of exactly 440.0 Hz (North America).

    Ch. Elster
    Aug 26 14:27:03 EDT 2019
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