Head orientation is necessary because interaural level differences plateau off-midline

Evidence

Acoustically, the entire head (and shoulders) makes part of the external ear. The distance between the two ears, located at opposite sides of the head, causes an arrival time difference of the sound wavefront that depends on the angle of incidence. A difference in sound level appears at high frequencies due to shadowing by the head to the side that is opposite to the sound source. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 726 (#corroborates, via linked claim)

Head movements have long been assumed to be important to satisfactory externalization in binaural headphone reproduction (Toole, 1970). The brain protests when the musicians and the performance venue move with the head. But mismatched HRTFs are a logical contributing factor to the perceptual error. — Toole, Floyd E, Sound reproduction- the acoustics and…, 290 (#expands, via linked claim)

Categorization

• XREF: connects to: Head movement and pinna shape resolve cone-of-confusion ambiguities; Head shading creates interaural level differences used for sound localization — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 726; Head movement resolves directional ambiguity and explains headphone sounds seeming internal — Toole, Floyd E, Sound reproduction- the acoustics and…, 290 (+1 more)

Related

• Head shading creates interaural level differences used for sound localization (similarity 0.91)
• Head movement and pinna shape resolve cone-of-confusion ambiguities (similarity 0.90)
• Head symmetry creates a cone of directions where sound localization is ambiguous (similarity 0.90)
• Head movement resolves directional ambiguity and explains headphone sounds seeming internal (similarity 0.89)
• Headphone sounds are usually lateralized inside the head. (similarity 0.89)
• Head-motion-dependent sound changes are required for external sound localization (similarity 0.87)
• Head separation between ears produces arrival-time and intensity cues for direction (similarity 0.87)
• Head shadowing gives roughly 6 dB interaural amplitude difference near 1.85 kHz (similarity 0.86)
• HRTFs encode direction through head, ear, and torso shape filtering (similarity 0.86)
• Lack of head-tracking dynamic cues causes headphone audio to sound internalized (similarity 0.86)
• Head intensity-shading fails below the frequency where head size reaches one-third wavelength (similarity 0.86)
• The head shadows and reflects sound to create level differences between the ears. (similarity 0.85)
• Head, torso, and shoulder acoustics shape the localization cues reaching each ear. (similarity 0.85)
• In-head localization stems from mismatched HRTFs and missing head tracking (similarity 0.85)
• Dynamic head tracking restores externalized sound localization in binaural reproduction. (similarity 0.84)

Broader Connections

• Head shading creates interaural level differences used for sound localization #corroborates (0.85) — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 726
• Head movement resolves directional ambiguity and explains headphone sounds seeming internal #expands (0.72) — Toole, Floyd E, Sound reproduction- the acoustics and…, 290