Headphone target curves can be derived computationally from HRTFs without a physical reference field.

Evidence

Møller et al. (1995b) derived a headphone target curve based on different sound fields using a large set of HRTFs measured at the blocked ear canal. HRTFs define the transfer functions, both the frequency and phase responses at the entrance to the ear, for each direction and distance of a sound source. HRTFs capture both interaural time (ITD) and intensity (IID) differences and 491. spectral cues that humans use to localize sound sources in space (Blauert, 1983). By selecting HRTFs from the appropriate directions and distances and integrating them, Møller et al. derived transfer functions of reference sound fields ranging from the FF to the DF and anything in between. This method eliminated the need for a physical reference sound field, making headphone calibration more practical and reproducible. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1767

Categorization

• DEFINE: Defines HRTFs precisely: transfer functions (frequency and phase) at the blocked ear canal, capturing ITD, IID, and spectral localization cues.
• QUESTION: How exactly is the blocked ear canal HRTF measured, and how does ‘blocked’ differ from other measurement points (eardrum, open canal)? Worth pinning down for the measurement chapter.