The outer ear’s resonant cavities enable elevation perception where other cues fail

Evidence

The pinna (Figure 12.4a) makes important contributions to the front–back and up–down differences at frequencies above 4 kHz (Blauert, 1996). The cavities resonate at specific frequencies and affect signals in the ear canal depending on the angle of incidence of sound from a sound source. In particular, the perception of elevation of a source in the median plane, where the ear canal signals are practically equivalent, is aided by the direction-dependent filtering of sound by the pinna. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1405

Categorization

• DEFINE: Explains the mechanism by which pinna anatomy encodes sound-source elevation, a core definitional concept in spatial hearing.
• XREF: Connects to acoustic ‘keynote/figure’ soundscape concepts; the pinna acts as a direction-dependent spectral filter akin to sonic ‘figure’ shaping.