Effectiveness of time-varying echo information for target geometry identification in bat-inspired human echolocation

Miwa Sumiya; Kaoru Ashihara; Hiroki Watanabe; Tsutomu Terada; Shizuko Hiryu; Hiroshi Ando

doi:10.1371/journal.pone.0250517

Effectiveness of time-varying echo information for target geometry identification in bat-inspired human echolocation

PLoS One. 2021 May 5;16(5):e0250517. doi: 10.1371/journal.pone.0250517. eCollection 2021.

Authors

Miwa Sumiya^{1

2}, Kaoru Ashihara³, Hiroki Watanabe⁴, Tsutomu Terada⁵, Shizuko Hiryu⁶, Hiroshi Ando¹

Affiliations

¹ Center for Information and Neural Networks (CiNet), National Institute of Information and Communications Technology (NICT), Seika-cho, Kyoto, Japan.
² Research Fellow of Japan Society for the Promotion of Science, Chiyoda-ku, Tokyo, Japan.
³ Human Informatics and Interaction Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan.
⁴ Faculty of Information Science and Technology, Hokkaido University, Sapporo, Hokkaido, Japan.
⁵ Graduate School of Engineering, Kobe University, Kobe, Hyogo, Japan.
⁶ Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto, Japan.

Abstract

Bats use echolocation through flexible active sensing via ultrasounds to identify environments suitable for their habitat and foraging. Mimicking the sensing strategies of bats for echolocation, this study examined how humans acquire new acoustic-sensing abilities, and proposes effective strategies for humans. A target geometry identification experiment-involving 15 sighted people without experience of echolocation-was conducted using two targets with different geometries, based on a new sensing system. Broadband frequency-modulated pulses with short inter-pulse intervals (16 ms) were used as a synthetic echolocation signal. Such pulses mimic buzz signals emitted by bats for echolocation prior to capturing their prey. The study participants emitted the signal from a loudspeaker by tapping on Android devices. Because the signal included high-frequency signals up to 41 kHz, the emitted signal and echoes from a stationary or rotating target were recorded using a 1/7-scaled miniature dummy head. Binaural sounds, whose pitch was down-converted, were presented through headphones. This way, time-varying echo information was made available as an acoustic cue for target geometry identification under a rotating condition, as opposed to a stationary one. In both trials, with (i.e., training trials) and without (i.e., test trials) answer feedback immediately after the participants answered, the participants identified the geometries under the rotating condition. Majority of the participants reported using time-varying patterns in terms of echo intensity, timbre, and/or pitch under the rotating condition. The results suggest that using time-varying patterns in echo intensity, timbre, and/or pitch enables humans to identify target geometries. However, performance significantly differed by condition (i.e., stationary vs. rotating) only in the test trials. This difference suggests that time-varying echo information is effective for identifying target geometry through human echolocation especially when echolocators are unable to obtain answer feedback during sensing.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Biomimetics*
Chiroptera / physiology*
Echolocation*
Humans

Grants and funding

This study was supported by JSPS KAKENHI Grant Number JP18J01429 (Grant-in-Aid for JSPS Fellows) to MS. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.