Game Development Reference

In-Depth Information

peak pressures relative to ambient is
−A
P
to +
A
P
. Assuming a harmonic wave, we can

write:

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
.