Human localisation ability using active echolocation

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Human localisation ability using active
echolocation

• David Edwards
• Human factors PhD
• presentation day
• 1st July 2009

Supervisors Prof. R. Allen and Dr. D. Rowan
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What is echolocation?
An understanding of human ability to use
echolocation cues is a step to understanding
binaural hearing system, learning effects and
ability to use cues from stimuli that are
theoretically difficult to process.
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What has been discovered?

• Human subjects can detect, discriminate
• and localise objects though there is huge
• variability between subjects (Cornell
• studies, pilot work)
• Previous localisation studies at 90 cm have found
  some ability to localise but results arent
  overwhelming

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Objective measurements of auditory cues
Experimental rig (a) KEMAR positioning (b) board
placement Distance ranged from 40 to 300 cm
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Analysis of recordings a work in progress

• Analysis of ITD/ILD cues in progress indicates
  that ILD cues are basis for localisation
• Direct and reflected signal similar in magnitude
  at 90 cm

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Investigation localisation ability based on board
localisation task

• 12 subjects
• 3 sessions
• 60 trials per
• stimuli per
• session

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Initial results
Trained subject using 3s with close speakers in
quiet d 2.9 (92) in noise (SNR 0), d 1.3
(73)
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Questions to be addressed

• Why the dramatic difference between free field
  and simulated echolocation tasks?
• What cues are available in human localisation
  tasks?
• How good is localisation ability using different
  signals?
• Can the precedence effect be overcome with
  training?
• Can binaural processing strategies be
  incorporated into hearing aids to tackle the
  cocktail party effect?

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Questions
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