Acoustic Concepts, Class 4

  1. When an electric guitar is connected to a speaker, the vibrating guitar string and the cone of the speaker move back and forth in perfect synchronicity. 

  2. The rate of vibration of a monochord string is affected by its length, thickness, and tension on the string. 

  3. Decreasing the effective length of a vibrating string by half doubles the rate at which it vibrates.

  4. A vibrating string moves back and forth as a whole. Segments of the string also vibrate at rates that are fractions of the whole (halves, thirds, etc.). The amplitude of the movement of segments of the string diminishes as a function of the length of the segment. (In other words, the amplitude of the movement of a segment that is half the length of the whole will be less than the movement of the whole.)

  5. This movement of the string as a whole and its respective segments generates a primary movement that is known as the fundamental frequency and a series of higher frequencies that are multiples of fundamental frequencies. For example, if the fundamental frequency is 40 Hz, a series of higher frequencies will be generated as follows:  80 Hz, 120 Hz, 160 Hz, 200 Hz, etc.

  6. The series of higher frequencies that result from vibration of segments of the string are known as overtones. The overtones of a vibrating object give a sound its characteristic quality.