Research overview: pinna-shaped spectral cues for sound localization

The shape of the external ear filters incoming sound in frequency-dependent ways, creating spectral cues the brain uses to judge a sound's elevation and to refine localization. This overview surveys how the feline pinna imposes such spectral shaping, including notches and peaks in the sound spectrum that vary with direction. Because the pinna is mobile, cats can actively alter these cues by repositioning the ear. The survey relates pinna acoustics to the cat's strong localization performance, especially for the vertical dimension where interaural timing cues alone are insufficient. It discusses how the directional filtering of the pinna supplies information that complements the timing and level differences between the two ears. Understanding pinna spectral cues shows that feline ear shape is not incidental but an acoustic instrument, and that the cat's ability to place sounds in three-dimensional space depends partly on the form of the ear itself.