Sound Propagation Physics: Doppler Effect and Distance Attenuation Curves: Fundamental Mechanics and Deep Mathematical Modeling

[Luke Stewart]

I’ve been digging into how competitive game engines model sound attenuation, and I’m hitting conceptual gaps I can’t resolve solo. The inverse square law assumes free-field propagation, but real maps have reflections, diffraction, and that frequency-dependent atmospheric absorption term that scales with humidity and temperature

"Ryzen 9 7950X3D | RTX 4090 24GB | Lian Li O11 Dynamic EVO"

[Henry Howard]

Great topic, and I’m glad to see someone actually digging into the math rather than just “spatial audio feels immersive.” Let’s start with the Doppler effect because it’s the part most people get subtly wrong in-game. The classical formula is f’ = f × (v + vᵣ)/(v + vₛ), where v is the speed of sound (~343 m/s at 20°C), vᵣ is the receiver’s velocity component along the line of sight, and vₛ is the source’s. The critical detail that gets glossed over is that these are signed projections onto the line of sight, not raw speeds—so a source moving perpendicular to you at the moment of closest approach produces zero instantaneous shift, even though it’s moving fast. Real engines like Wwise and FMOD apply a smooth Doppler curve with a configurable “Doppler factor” (usually 1.0) and a “distance factor” to prevent the pitch from jumping unnaturally as targets track. For competitive play this matters because a properly tuned Doppler shift on approaching footsteps gives you subframe timing cues; too much and it’s an audible artifact, too little and you lose the directional approach information entirely.

On distance attenuation, the fundamental baseline is the inverse-square law, where intensity scales as 1/r

[Author]

Posts