HRTF (Head-Related Transfer Function)

A Head-Related Transfer Function (HRTF) describes how the human head, pinnae, and torso modify incoming sound as a function of frequency and direction of arrival. HRTFs capture the spectral filtering and interaural differences that the brain uses to localize sounds in three dimensions. Each direction has a unique HRTF pair (left and right ears), and the complete set is called the HRTF dataset. In room acoustics, HRTFs are applied to simulated or measured room impulse responses to create binaural auralizations that simulate realistic spatial hearing over headphones. Generic HRTF datasets (e.g., KEMAR, HUTUBS) are commonly used, though individualized HRTFs provide more accurate externalization. HRTFs are essential for virtual reality audio, spatial audio rendering, and evaluating acoustic design metrics like apparent source width and listener envelopment. The MIT KEMAR dataset and the CIPIC database are widely used in research and commercial applications.