Near-coincident arrays add arrival-time differences to produce a more spacious stereo image

Near-coincident techniques deliberately space the microphone capsules apart so that sounds arriving off-axis reach one mic slightly before the other. These tiny time delays provide additional stereo cues that coincident techniques cannot reproduce. ORTF specifies 17 cm between diaphragms at a 110-degree angle, approximating human ear geometry, and was developed by French radio for orchestral recording. Spaced omni pairs exploit the same principle with omnidirectional mics separated by roughly the width of a human head. The result is a more spacious, immersive image than coincident setups — at the cost of reduced mono compatibility, because the time delays produce comb-filtering artefacts when channels are summed.

Examples

ORTF: cardioid pair, 17 cm separation, 110 degree angle. Spaced omnis: two omni mics ~6–18 inches apart, relying on arrival-time alone for stereo information. Listen to how the image collapses differently than X-Y when summed to mono.

Assessment

Contrast X-Y with ORTF: which produces a wider stereo image? Which is more mono-compatible? Explain the physical mechanism behind each.