title: Modeling human echolocation of near-range targets with an audible sonar.
abstract: Blind humans echolocate nearby targets by emitting palatal clicks and perceiving echoes that the auditory system is not able to resolve temporally. The mechanism for perceiving near-range echoes is not known. This paper models the direct mouth-to-ear signal (MES) and the echo to show that the echo enhances the high-frequency components in the composite MES/echo signal with features that allow echolocation. The mouth emission beam narrows with increasing frequency and exhibits frequency-dependent transmission notches in the backward direction toward the ears as predicted by the piston-in-sphere model. The ears positioned behind the mouth detect a MES that contains predominantly the low frequencies contained in the emission. Hence the high-frequency components in the emission that are perceived by the ears are enhanced by the echoes. A pulse/echo audible sonar verifies this model by echolocating targets from 5 cm range, where the MES and echo overlap significantly, to 55 cm. The model predicts that unambiguous ranging occurs over a limited range and that there is an optimal range that produces the highest range resolution.
authors.affiliation: Department of Electrical Engineering, Yale University, 15 Prospect Street, New Haven, Connecticut 06520-8284, USA.
authors.forename: Roman
authors.initials: R
authors.lastname: Kuc
authors.affiliation: Computer Science Department, Iona College, 715 North Avenue, New Rochelle, New York 10801, USA.
authors.forename: Victor
authors.initials: V
authors.lastname: Kuc
mesh_terms: D000161:Acoustic Stimulation; D000162:Acoustics / Q000295:instrumentation; D000669:Amplifiers, Electronic; D001306:Auditory Pathways / Q000502:physiology*; D054644:Ear Auricle / Q000033:anatomy & histology / Q000502:physiology*; D006801:Humans; D008962:Models, Theoretical; D009038:Motion; D009055:Mouth / Q000033:anatomy & histology / Q000502:physiology*; D010898:Pitch Perception; D011312:Pressure; D017603:Signal Detection, Psychological; D013016:Sound; D013017:Sound Localization; D013018:Sound Spectrography; D013997:Time Factors; D014160:Transducers, Pressure