4.3. SIMPLE SPATIAL AUDIO SYSTEMS

Spatial audio reproduction systems are generally categorized by transducer configuration and delivery technique:

1. Two-Channel Stereo (Loudspeakers)

Standard stereophonic setups use two loudspeakers positioned symmetrically in front of the listener (typically at $\pm 30^\circ$).

• By varying the relative gain between channels (panning / interchannel level differences), a “phantom center” or virtual source can be positioned between the speakers.
• Limitation: Virtual sources cannot be positioned behind, above, or around the listener without specialized acoustic crosstalk cancellation or multichannel surround arrays.

2. Multichannel Surround Sound

Surround setups use discrete loudspeaker channels distributed around the room (e.g., 5.1, 7.1, or 3D formats like 22.2).

• Techniques such as Vector Base Amplitude Panning (VBAP) distribute energy across adjacent speaker triplets to position sources across 360°.
• Limitation: High cost, strict acoustic room requirements, and sweet-spot localization constraints.

3. Binaural Reproduction (Headphones)

Binaural systems deliver sound directly into the listener’s ear canals over headphones.

• By convolving monaural source signals with Head-Related Impulse Responses (HRIRs) measured for each ear, full 3D spatialization (azimuth, elevation, and distance) can be achieved over standard stereo headphones.
• Headphone reproduction eliminates room reflections and interchannel acoustic crosstalk, making it the ideal delivery platform for personalized spatial audio.