Abstract—Representing and interacting with the external
world constitutes a major challenge for persons who are blind or
visually impaired. Nonvisual sensory modalities such as audition
and somatosensation assume primary importance. Some nonhuman
species, such as bats and dolphins, sense by active echolocation,
in which emitted acoustic pulses and their reflections are
used to sample the environment. Active echolocation is also used
by some blind humans, who use signals such as tongue clicks
or cane taps as mobility aids. The ultrasonic pulses employed
by echolocating animals have several advantages over those
used by humans, including higher spatial resolution and fewer
diffraction artifacts. However, they are unavailable to unaided
humans. Here we present a device that combines principles of
ultrasonic echolocation and spatial hearing to present human
users with environmental cues that are i) not otherwise available
to the human auditory system and ii) richer in object and
spatial information than the more heavily processed sonar cues
of other assistive devices. The device consists of a wearable
headset with an ultrasonic emitter and stereo microphones
affixed with artificial pinnae. The echoes of ultrasonic pulses
are recorded and time-stretched to lower their frequencies into
the human auditory range before being played back to the user.
We tested performance among naive and experienced sighted
volunteers using a set of localization experiments. Naive subjects
were able to make laterality and distance judgments, suggesting
that the echoes provide innately useful information without
prior training. Naive subjects were unable to make elevation
judgments. However, in localization testing one trained subject
demonstrated an ability to judge elevation as well. This suggests
that the device can be used to effectively examine the environment
and that the human auditory system can rapidly adapt to these
artificial echolocation cues. We contend that this device has the
potential to provide significant aid to blind people in interacting
with their environment.
Abstract—Representing and interacting with the external
world constitutes a major challenge for persons who are blind or
visually impaired. Nonvisual sensory modalities such as audition
and somatosensation assume primary importance. Some nonhuman
species, such as bats and dolphins, sense by active echolocation,
in which emitted acoustic pulses and their reflections are
used to sample the environment. Active echolocation is also used
by some blind humans, who use signals such as tongue clicks
or cane taps as mobility aids. The ultrasonic pulses employed
by echolocating animals have several advantages over those
used by humans, including higher spatial resolution and fewer
diffraction artifacts. However, they are unavailable to unaided
humans. Here we present a device that combines principles of
ultrasonic echolocation and spatial hearing to present human
users with environmental cues that are i) not otherwise available
to the human auditory system and ii) richer in object and
spatial information than the more heavily processed sonar cues
of other assistive devices. The device consists of a wearable
headset with an ultrasonic emitter and stereo microphones
affixed with artificial pinnae. The echoes of ultrasonic pulses
are recorded and time-stretched to lower their frequencies into
the human auditory range before being played back to the user.
We tested performance among naive and experienced sighted
volunteers using a set of localization experiments. Naive subjects
were able to make laterality and distance judgments, suggesting
that the echoes provide innately useful information without
prior training. Naive subjects were unable to make elevation
judgments. However, in localization testing one trained subject
demonstrated an ability to judge elevation as well. This suggests
that the device can be used to effectively examine the environment
and that the human auditory system can rapidly adapt to these
artificial echolocation cues. We contend that this device has the
potential to provide significant aid to blind people in interacting
with their environment.
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