People's Ability to Detect Objects Using Click-Based Echolocation: A Direct Comparison between Mouth-Clicks and Clicks Made by a Loudspeaker

Abstract

Echolocation is the ability to use reflected sound to obtain information about the spatial environment. Echolocation is an active process that requires both the production of the emission as well as the sensory processing of the resultant sound. Appreciating the general usefulness of echo-acoustic cues for people, in particular those with vision impairments, various devices have been built that exploit the principle of echolocation to obtain and provide information about the environment. It is common to all these devices that they do not require the person to make a sound. Instead, the device produces the emission autonomously and feeds a resultant sound back to the user. Here we tested if echolocation performance in a simple object detection task was affected by the use of a head-mounted loudspeaker as compared to active clicking. We found that 27 sighted participants new to echolocation did generally better when they used a loudspeaker as compared to mouth-clicks, and that two blind participants with experience in echolocation did equally well with mouth clicks and the speaker. Importantly, performance of sighted participants' was not statistically different from performance of blind experts when they used the speaker. Based on acoustic click data collected from a subset of our participants, those participants whose mouth clicks were more similar to the speaker clicks, and thus had higher peak frequencies and sound intensity, did better. We conclude that our results are encouraging for the consideration and development of assistive devices that exploit the principle of echolocation.

Fig 1

(a) Waveform of an individual click as played through the speaker (recorded with DPA SMK-SC4060 with protective grid removed and TASCAM DR100-MKII at 24bit and 96kHz) (b) The click’s frequency spectrum.

Fig 2. Performance split by distance and sound.

Error bars represent SEM across participants. ** p< .01; *** p<.001.

Fig 3. Performance split by session, distance and sound.

Error bars represent SEM across participants. *** p<.001.

Fig 4. Data for B1 and B2 plotted in comparison to data from sighted participants split by session, distance and sound (i.e. data replotted as from Fig 3).

Note that the plot for B1 has two results superimposed. For results of significance tests between sighted participants and B1 and B2 please see Table 2.

Fig 5. Scatterplots between individual acoustic variables and performance.

Data from B1 and B2 are highlighted in the plots.