• Treat speaker as sphere expanding and contracting sinusoidally. For , distance is the near field. In the near field everything expands and contracts together. . The total power radiated is then .
• For a dipole source, the radiated power drops by and is no longer isotropic. varies as
• Quadrupole source, Power is related to power of monopole by , . Tuning forks radiate as a quadropole.

source psfile jl@crush.caltech.edu index