Multiple listeners off the sweet spot need extra channels for envelopment.

Evidence

NOTE: The previous sentence focused on “a listener”. If there is an audience of multiple listeners located away from the symmetrical sweet spot, more channels will be necessary to generate similarly enveloping effects over the enlarged listening area. This is where the more elaborate immersive systems with added elevation channels have advantages. In the demonstrations I have heard it was impressive how stable the spatial illusions were as I moved around the listening room. More channels clearly can deliver a more believable sound field for multiple listeners. — Toole, Floyd E, Sound reproduction- the acoustics and…, 738

Categorization

• XREF: Connects to sweet-spot discussions in multichannel audio and the trade-off between single-listener fidelity and audience coverage.