The detection of ‘virtual’ objects using echoes by humans: Spectral cues

Daniel Rowan,Lauren Archer,Hannah Holmes,Hayley Cozens,Ricardo Guzman Lopez,Timos Papadopoulos,Robert Allen,Amanda Goodhew,David Edwards

doi:10.1016/j.heares.2017.04.008

Abstract

Some blind people use echoes to detect discrete, silent objects to support their spatial orientation/navigation, independence, safety and wellbeing. The acoustical features that people use for this are not well understood. Listening to changes in spectral shape due to the presence of an object could be important for object detection and avoidance, especially at short range, although it is currently not known whether it is possible with echolocation-related sounds. Bands of noise were convolved with recordings of binaural impulse responses of objects in an anechoic chamber to create ‘virtual objects’, which were analysed and played to sighted and blind listeners inexperienced in echolocation. The sounds were also manipulated to remove cues unrelated to spectral shape. Most listeners could accurately detect hard flat objects using changes in spectral shape. The useful spectral changes for object detection occurred above approximately 3 kHz, as with object localisation. However, energy in the sounds below 3 kHz was required to exploit changes in spectral shape for object detection, whereas energy below 3 kHz impaired object localisation. Further recordings showed that the spectral changes were diminished by room reverberation. While good high-frequency hearing is generally important for echolocation, the optimal echo-generating stimulus will probably depend on the task.

Highlights

Some sighted, visually impaired and blind people are able to use auditory cues from echoes to determine various features of otherwise silent objects (Kolarik et al, 2014) and to avoid objects duringD
We previously considered the effect of this interference on a binaural object localisation task (Rowan et al, 2013, 2015); one finding was that excluding energy in the emission below 2 kHz improved object localisation
The result was the selection of the impulse responses (IRs) from the right ear with the metal board at 4 m and a level rove of ±14 dB using a rectangular distribution. (We argue in the Discussion that the main finding of this experiment will apply to shorter distances, for which the across-channel level cue may be more relevant.) That combination produced a maximum score expected from the use of the within-channel level of 63%

Summary

Introduction

Visually impaired and blind people are able to use auditory cues from echoes to determine various features of otherwise silent objects (Kolarik et al, 2014) and to avoid objects duringD. Visually impaired and blind people are able to use auditory cues from echoes to determine various features of otherwise silent objects (Kolarik et al, 2014) and to avoid objects during. We previously considered the effect of this interference on a binaural object localisation task (Rowan et al, 2013, 2015); one finding was that excluding energy in the emission below 2 kHz improved object localisation. This finding may not generalise to object detection. We focus on elucidating the cues to object detection available when there is interference between the echo and the emission

Objectives

Methods

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Conclusion