A gaming headset advertising surround sound has two drivers, one per ear. The directional effect is created by processing rather than by additional speakers, and the method has clear limits.
Direction is inferred from how ears filter sound
Human hearing locates sources using differences between the ears in arrival time and loudness, combined with filtering caused by the shape of the head and outer ear.
That filtering changes depending on where a sound comes from, so the ear's own geometry encodes direction into the signal before it reaches the eardrum.
Positional audio processing applies a model of this filtering to a game's sound sources, producing two channels that carry the cues the brain uses to place them.
The model is generic and ears are not
The filtering depends on individual anatomy, and processing is built from averaged measurements rather than from the listener's own ears.
A listener whose anatomy differs from the average receives cues that do not quite match what their brain expects, which weakens or distorts the effect.
This is why the same headset is convincing for one player and unremarkable for another, and why some systems now offer personalisation based on measurements or profiles.
Front and back confusion is the characteristic failure
Sources directly ahead and directly behind produce similar differences between the ears, so the cues distinguishing them are subtle and easily lost.
In life, small head movements resolve the ambiguity instantly because the cues change as the head turns. Static processing offers no such correction.
Head tracking addresses this by updating the audio as the player moves, which is why tracked systems locate sources far more convincingly than untracked ones.
Multi-driver headsets are a different approach
Some headsets place several small drivers in each cup to produce direction physically rather than through processing.
The drivers sit close to the ear, so the geometric differences are small and each driver is necessarily compromised in size and quality.
Most listeners find well-implemented processing on good stereo drivers preferable, which is why the multi-driver approach has become uncommon.
The game's audio engine is the deciding factor
Processing can only position sounds that the game supplies with positions. Audio mixed into fixed channels before it reaches the system cannot be repositioned.
Games that treat every sound as an object in space give the processing full information and locate sources far more accurately.
This is why the quality of positional audio tracks the game more closely than the headset, and why the same hardware performs unevenly across a library.