title: State-space models of head-related transfer functions for virtual auditory scene synthesis.
abstract: This study investigates the use of reduced-order state-space models of collections of head-related transfer functions (HRTFs). Recent head-phone applications have motivated interest in binaural displays that can render multiple simultaneous virtual sound sources, acoustic reflections, and source and listener motion. In the present study, a multi-direction framework is considered that can render such phenomena by filtering source signals with a collection of HRTFs rather than individual HRTFs. The collection of HRTFs is implemented in the state-space, and approximation techniques are applied to construct low-order approximants that are indiscriminable from full-order HRTFs. Two experiments are described in which five observers are asked to discriminate between state-space and full-order renderings. Depending on the stimulus conditions and discrimination task, order thresholds of 7<or=N<or=24 are sufficient for an array of 50 HRTFs surrounding the listener. For comparison, a reference system of truncated minimum-phase impulse responses is also considered.
authors.affiliation: Applied Physics Laboratory, Johns Hopkins University, Laurel, Maryland 20723, USA. norman.adams@jhuapl.edu
authors.forename: Norman H
authors.initials: NH
authors.lastname: Adams
authors.forename: Gregory H
authors.initials: GH
authors.lastname: Wakefield
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000465:Algorithms; D001307:Auditory Perception; D001309:Auditory Threshold; D004777:Environment; D006257:Head; D006801:Humans; D008953:Models, Anatomic; D009483:Neuropsychological Tests; D009622:Noise; D011571:Psychoacoustics; D011594:Psychometrics; D013647:Task Performance and Analysis; D055815:Young Adult