Pinna shape creates learned, person-specific comb filters that aid sound localization

Evidence

The first is to use the effect of our ears on the sounds we receive to resolve the angle and direction of the sound. This is due to the fact that sounds striking the pinnae are reflected into the ear canal by the complex set of ridges that exist on the ear. These pinnae reflections will be delayed, by a very small but significant amount, and so will form comb filter interference effects on the sound the ear receives. … The effect is also person specific, as we all have differently shaped ears and learn these cues as we grow up. Thus we get confused for a while when we change our acoustic head shape radically, for example by cutting very long hair short. We also find that if we hear sound recorded through other people’s ears, we may have a different ability to localize the sound, because the interference patterns are not the same as those for our ears. In fact, sometimes this localization capability is worse than when using our own ears, and sometimes it is better. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 731

Categorization

• DEFINE: Defines how pinna comb filtering and learned person-specific cues underpin directional hearing.
• XREF: Explains why generic binaural recordings sound wrong; relates to individualized HRTF personalization in spatial audio.