Game Development Reference
peak pressures relative to ambient is −A P to + A P . Assuming a harmonic wave, we can
ΔP = A P sin(kx - ωt - φ)
k is called the wave number and is equal to 2π/λ, where λ is the wave length. x is the
coordinate representing the position under consideration. ω is called angular, or cir‐
cular, frequency and is equal to 2π f , where f is the frequency of the sound wave. t
represents time. Finally, φ is called the phase angle, also known as the phase shift. It
represents an offset of the wave along the x-axis in this case.
With this equation, we can plot what Δ P at a particular x-location as a function of time.
Figure 26-4 illustrates such a plot assuming that A P , λ, and f are all equal to 1 and φ is
equal to 0.
Figure 26-4. Harmonic wave
Physically, if you were to measure the change in pressure over time at some point, x , the
plot would look like that shown in Figure 26-4 .