Mixed-order Ambisonics

This practice is called mixed-order, and it has consequences for the layout and interpretation of files, streams, or physical connections in Ambisonic data exchange.

Horizontal-only recordings or mixes are the most commonly encountered mixed-order signals, because the horizontal plane is by far the most likely location of musical or other performers, and the vast majority of playback systems deployed today does not have height capability.

However, such a system has an often-overlooked misfeature: as soon as a source leaves the equator, its sharpness and area of satisfactory reconstruction degrades rapidly to that of the (lower) periphonic order.

To address this issue, Travis (2009) suggested an augmented mixed-order scheme which retains its horizontal resolution even for elevated sources, while limiting the lower order "smear" to the vertical dimension.

However, they also propose an extended specification which makes use of an adaptor matrix that maps arbitrary data formats (such as legacy Furse-Malham signals) to the desired standardized outputs, and encompasses both #H#P and #H#V mixed order schemes.