HRTF and personalization
HRTF? What is it?
When a sound wave travels from a given location to our eardrums, it interacts with several parts of our body such as the head and the ears. All these reflections, diffractions and absorptions (depending mainly on the shape of our head and the structure of our outer ears) change the nature of the incoming sound according to its direction of origin. These interactions between sound and morphology can very well be represented as direction-dependent filters. These sound wave filters depend on the source’s position in space. Our auditory system has learned over time to associate each specific filter to its origin. This is how we recognize where a sound comes from. The representation of these directional changes as filters is called “Head Related Transfer Function” or HRTF.
If you want to simulate a sound coming from a given direction, you must filter it with the HRTF of this direction, play it with headphones at the entrance of the ear canal and the auditory system will position the sound as coming from this spot in space since it recognizes the directional signature. This is the basic principle behind all the Virtual Reality Audio engines.