### Exponentially Decaying Traveling Waves

Let denote the decay factor associated with propagation of a plane wave over distance at frequency rad/sec. For an ideal plane wave, there is no ``spreading loss'' (attenuation by ). Under uniform conditions, the amount of attenuation (in dB) is proportional to the distance traveled; in other words, the attenuation factors for two successive segments of a propagation path are*multiplicative*:

*exponential*function of distance .

^{3.3}

*Frequency-independent air absorption*is easily modeled in an acoustic simulation by making the substitution

**Next Section:**

Frequency-Dependent Air-Absorption Filtering

**Previous Section:**

Program for Acoustic Echo Simulation