Binaural direction cues alone cannot distinguish front from back or vertical source angle

Evidence

The aforementioned models of directional hearing do not explain how we can resolve front-to-back ambiguities or the elevation of the source. There are in fact two ways that are used by the human being to perform these tasks. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 729

Categorization

• QUESTION: The passage announces two additional mechanisms — worth chasing down what they are.
• XREF: connects to: Dynamic binaural head-movement cues override conflicting visual evidence of source location — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1460; Head movements resolve front-back ambiguity by creating direction-specific binaural cue changes — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1457