Depth Echolocation Learnt by Novice Sighted People

Abstract

Some blind people have developed a unique technique, called echolocation, to orient themselves in unknown environments. More specifically, by self-generating a clicking noise with the tongue, echolocators gain knowledge about the external environment by perceiving more detailed object features. It is not clear to date whether sighted individuals can also develop such an extremely useful technique. To investigate this, here we test the ability of novice sighted participants to perform a depth echolocation task. Moreover, in order to evaluate whether the type of room (anechoic or reverberant) and the type of clicking sound (with the tongue or with the hands) influences the learning of this technique, we divided the entire sample into four groups. Half of the participants produced the clicking sound with their tongue, the other half with their hands. Half of the participants performed the task in an anechoic chamber, the other half in a reverberant room. Subjects stood in front of five bars, each of a different size, and at five different distances from the subject. The dimension of the bars ensured a constant subtended angle for the five distances considered. The task was to identify the correct distance of the bar. We found that, even by the second session, the participants were able to judge the correct depth of the bar at a rate greater than chance. Improvements in both precision and accuracy were observed in all experimental sessions. More interestingly, we found significantly better performance in the reverberant room than in the anechoic chamber. The type of clicking did not modulate our results. This suggests that the echolocation technique can also be learned by sighted individuals and that room reverberation can influence this learning process. More generally, this study shows that total loss of sight is not a prerequisite for echolocation skills this suggests important potential implications on rehabilitation settings for persons with residual vision.

Bilingual Infants Demonstrate Advantages in Learning Words in a Third Language

“…() reported that adults likened these contrasts to hand claps and finger snaps (in addition to other nonlinguistic sounds). Likewise, an analysis of click consonants, finger snaps, and hand claps have revealed a series of acoustic similarities between these three sources of variation (Aguilar, ; Rojas, Hermosilla, Montero, & Espí, ; Tonelli, Brayda, & Gori, ). Perceptually, click consonants, hand claps, and finger snaps are similar in that they are all highly recognizable, rapid acoustic events that also share several acoustic properties.…”

Human echolocation - spatial resolution and signal properties

“…Although it had been thought by some that such additional factors would impair the ability to detect and discriminate objects, in a manner similar to the effect of background noise on sound localisation (Kolarik et al, 2014), Schenkman & Nilsson (2010) in fact showed that a reflecting object could be detected up to a distance of 100 cm in an anechoic chamber, but up to 200 cm in a conference room. Furthermore, in a study by Tonelli and colleagues (2016), in which the reverberation time was as long as 1.4 s (Tonelli et al, 2016), participants' ability to echolocate (both in the precision and accuracy of depth judgment) was still better in a reverberating room compared to an anechoic one. One theory for the cause of better performance in a more natural reverberating room is that "late echoes" -those echoes that reflect from walls and surrounding objects -may provide additional cues that aid in solving the task (Tonelli et al, 2016).…”

“…Furthermore, in a study by Tonelli and colleagues (2016), in which the reverberation time was as long as 1.4 s (Tonelli et al, 2016), participants' ability to echolocate (both in the precision and accuracy of depth judgment) was still better in a reverberating room compared to an anechoic one. One theory for the cause of better performance in a more natural reverberating room is that "late echoes" -those echoes that reflect from walls and surrounding objects -may provide additional cues that aid in solving the task (Tonelli et al, 2016). Gibson (1979) posits that a surplus of perceptual information, that approximates ecological conditions, can make perception more reliable and veridical, and this principle may apply here.…”

“…In comparing the use of an oral click to that of a finger-snap, for example, Tonelli, Brayda & Gori (2016) showed that novice echolocators learned just as well with either mode of emission, but at close distances to the object (30 cm) the oral click seemed to be the most useful. This oral click advantage may arise at such short ranges because the sound source of the oral click, compared to that of the finger-snap, ensures that an object directly in front of the echolocator at head-height can be effectively stimulated.…”

Auditory Feedback for Navigation with Echoes in Virtual Environments: Training Procedure and Orientation Strategies

“…Notably, in the absence of visual cues, head and body movements also play an important role in relation to auditory perception of space during navigation [29]. It has been noticed that sighted people are able to learn echolocation as well [16,47,52]. In the presence of two closely spaced audio signals some information gets suppressed, which influences echolocation quality, especially when visual feedback is present.…”