Individual ear shapes give each listener a unique head-related transfer function

Evidence

Modeling the effect of the head can be achieved using the head-related transfer function or HRTF, which accounts for the way the ears of a listener receive sound in three dimensions. The HRTF accounts for how head shadowing (see Figure 2.28), the acoustic effects of the concha (see Section 2.2.1) and ridges of the pinnae affect the sound arriving at the left and right eardrums. Our differing pinnae shapes mean that the acoustic properties of scattered sound waves from them are different and therefore individual. These pinnae ridges and the shape of the head are unique features of individual listeners, and the brain learns the acoustic consequences early on in life. Since these acoustic variations to input sounds at our two ears are responsible for our perception of everyday sounds in three dimensions (both horizontally and vertically), it is important that these acoustic cues are accounted for and therefore exist in reproduced sound if the desired result is a 3-D listening experience. — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 736

Categorization

• DEFINE: Defines HRTF and breaks down what it accounts for across head shadowing, concha, and pinnae ridges.
• XREF: The idea that the brain learns a personal acoustic signature early in life echoes themes about learned soundscapes in Schafer’s work. — connects to: Head and pinna scattering imprint direction-dependent spectral notches onto the ear signal. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1451; Individual HRTF measurements give the most accurate external ear emulation — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 1608; Each person’s unique ear shape requires individualized acoustic rendering for 3-D audio — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 736
• SEED: Could angle an essay on why personalized audio (HRTF-tailored headphones) promises a distinctively intimate 3D listening, unlike one-size-fits-all sound.