title: Psychophysics of human echolocation.
abstract: The skills of some blind humans orienting in their environment through the auditory analysis of reflections from self-generated sounds have received only little scientific attention to date. Here we present data from a series of formal psychophysical experiments with sighted subjects trained to evaluate features of a virtual echo-acoustic space, allowing for rigid and fine-grain control of the stimulus parameters. The data show how subjects shape both their vocalisations and auditory analysis of the echoes to serve specific echo-acoustic tasks. First, we show that humans can echo-acoustically discriminate target distances with a resolution of less than 1 m for reference distances above 3.4 m. For a reference distance of 1.7 m, corresponding to an echo delay of only 10 ms, distance JNDs were typically around 0.5 m. Second, we explore the interplay between the precedence effect and echolocation. We show that the strong perceptual asymmetry between lead and lag is weakened during echolocation. Finally, we show that through the auditory analysis of self-generated sounds, subjects discriminate room-size changes as small as 10%.In summary, the current data confirm the practical efficacy of human echolocation, and they provide a rigid psychophysical basis for addressing its neural foundations.
authors.affiliation: Department of Biology, University of Munich, Martinsried, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Schörnich
authors.forename: Ludwig
authors.initials: L
authors.lastname: Wallmeier
authors.forename: Nikodemus
authors.initials: N
authors.lastname: Gessele
authors.forename: Andreas
authors.initials: A
authors.lastname: Nagy
authors.forename: Michael
authors.initials: M
authors.lastname: Schranner
authors.forename: Daniel
authors.initials: D
authors.lastname: Kish
authors.forename: Lutz
authors.initials: L
authors.lastname: Wiegrebe
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D001766:Blindness / Q000503:physiopathology*; D004455:Echolocation / Q000502:physiology*; D006801:Humans; D009433:Neural Inhibition / Q000502:physiology; D011571:Psychoacoustics; D011601:Psychophysics / Q000379:methods; D012683:Sensory Deprivation / Q000502:physiology; D013017:Sound Localization / Q000502:physiology*