Sound Properties

idk

subjective experience

objective measure of the rate at which the wave motion carries energy.
$P = \frac{E}{t} ⟹ I = \frac{E \div t}{A} ⟹ I = \frac{E}{A t} ⟹ I = \frac{P}{A}$
a wave spreads out spherically from a point source. when the distance is doubled, the energy by the wave will spread out over four times the original area.
the behaviour is thus an inverse square law:
- $I \propto \frac{1}{r ^{2}}$
- if the intensity is $I_{0}$ at a particular distance $r_{0}$ , then $I_{0} = \frac{1}{r _{0} ^{2}}$
  - what??
- since the proportionality constants are the same, then the ratio of the intensities given as
  - $I_{0} r_{0}^{2} = I_{f} r_{f}^{2}$
- $L (d b) = 10 lo g \frac{I}{I _{0}}$
- $\frac{I _{f}}{I _{0}} = \frac{r _{0} ^{2}}{r _{f} ^{2}}$ worth remembering!!!!!!!!!!!!!!!