Abstract
The presented review discusses recent research on human echolocation by blind and sighted subjects, aiming to classify and evaluate the methodologies most commonly used when testing active echolocation methods. Most of the reviewed studies compared small groups of both blind and sighted volunteers, although one in four studies used sighted testers only. The most common trial procedure was for volunteers to detect or localize static obstacles, e.g., discs, boards, or walls at distances ranging from a few centimeters to several meters. Other tasks also included comparing or categorizing objects. Few studies utilized walking in real or virtual environments. Most trials were conducted in natural acoustic conditions, as subjects are marginally less likely to correctly echolocate in anechoic or acoustically dampened rooms. Aside from live echolocation tests, other methodologies included the use of binaural recordings, artificial echoes or rendered virtual audio. The sounds most frequently used in the tests were natural sounds such as the palatal mouth click and finger snapping. Several studies have focused on the use of artificially generated sounds, such as noise or synthetic clicks. A promising conclusion from all the reviewed studies is that both blind and sighted persons can efficiently learn echolocation.Keywords:
echolocation, blindness, testing methodologyReferences
1. Andrade R., Baker S., Waycott J., Vetere F. (2018), Echo-house: Exploring a virtual environment by using echolocation, [in:] Proceedings of the 30th Australian Conference on Computer-Human Interaction, pp. 278–289, https://doi.org/10.1145/3292147.3292163
2. Andrade R., Waycott J., Baker S., Veterie F. (2021), Echolocation as a means for people with visual impairment (PVI) to acquire spatial knowledge of virtual space, ACM Transactions on Accessible Computing, 14(1): 1–25, https://doi.org/10.1145/3448273
3. Arias C., Bermejo F., Hüg M.X., Venturelli N., Rabinovich D., Skarp A.O. (2012), Echolocation: An action-perception phenomenon, New Zealand Acoustics, 25(2): 20–27.
4. Arias C., Ramos O.A. (1997), Psychoacoustic tests for the study of human echolocation ability, Applied Acoustics, 51(4): 399–419, https://doi.org/10.1016/S0003-682X%2897%2900010-8
5. Bogus M., Bujacz M. (2021), Analysis of mouth click sounds used in echolocation, [in:] 2021 Signal Processing Symposium (SPSympo), pp. 23–25, https://doi.org/10.1109/SPSympo51155.2020.9593698
6. Bujacz M. et al. (2018), EchoVis: Training echolocation using binaural recordings – Initial benchmark results, [in:] Computers Helping People with Special Needs. ICCHP 2018. Lecture Notes in Computer Science, Miesenberger K., Kouroupetroglou G. [Eds.], Vol. 10897, pp. 102–109, https://doi.org/10.1007/978-3-319-94274-2_15
7. Bujacz M., Górski G., Matysik K. (2021), Mobile game development with spatially generated reverberation sound, [in:] Advances in Systems Engineering. ICSEng 2021. Lecture Notes in Networks and Systems, Borzemski L., Selvaraj H., Swiatek J. [Eds.], Vol. 364, pp. 69–78, Springer, https://doi.org/10.1007/978-3-030-92604-5_7
8. Bujacz M., Królak A., Górski G., Matysik K., Witek P. (2022a), Echovis – A collection of human echolocation tests performed by blind and sighted individuals: A pilot study, British Journal of Visual Impairment.
9. Bujacz M., Skulimowski P., Królak A., Sztyler B., Strumiłło P. (2022b), Comparison of echolocation abilities of blind and normally sighted humans using different source sounds, Vibrations in Physical Systems, 33(2), https://doi.org/10.21008/j.0860-6897.2022.2.13
10. Castillo-Serrano J.G., Norman L.J., Foresteire D., Thaler L. (2021), Increased emission intensity can compensate for the presence of noise in human click-based echolocation, Scientific Reports, 11: 1750, https://doi.org/10.1038/s41598-021-81220-9
11. Cooper S., Velazco P., Schantz H. (2020), Navigating in darkness: Human echolocation with comments on bat echolocation, Journal of the Human Anatomy and Physiology Society, 24(2): 36–41, https://doi.org/10.21692/haps.2020.016
12. Corder G.W., Foreman D.I. (2009), Nonparametric Statistics for Non-Statisticians: A Step-by-Step Approach, John Wiley & Sons, Inc.
13. Dobrucki A., Plaskota P., Pruchnicki P., Pec M., Bujacz M., Strumiłło P. (2010). Measurement system for personalized head-related transfer functions and its verification by virtual source localization trials with visually impaired and sighted individuals, Journal of The Audio Engineering Society, 58(9): 724–738.
14. Dodsworth C., Norman L.J., Thaler L. (2020), Navigation and perception of spatial layout in virtual echo-acoustic space, Cognition, 197: 104185, https://doi.org/10.1016/j.cognition.2020.104185
15. Ekkel M.R., van Lier R., Steenbergen B. (2017), Learning to echolocate in sighted people: A correlational study on attention, working memory and spatial abilities, Experimental Brain Research, 235: 809–818, https://doi.org/10.1007/s00221-016-4833-z
16. Fiehler K., Schütz I., Meller T., Thaler L. (2015), Neural correlates of human echolocation of path direction during walking, Multisensory Research, 28(1–2): 195–226, https://doi.org/10.1163/22134808-00002491
17. Flanagin V.L. et al. (2017), Human exploration of enclosed spaces through echolocation, Journal of Neuroscience, 37(6): 1614–1627, https://doi.org/10.1523/JNEUROSCI.1566-12.2016
18. Fundacja Instytut Rozwoju Regionalnego [FIRR] (2019), Training Curriculum. Active Echolocation for People with Visual Impairment.
19. Gori M., Sandini G., Martinoli C., Burr D.C. (2014), Impairment of auditory spatial localization in congenitally blind human subjects, Brain: A Journal of Neurology, 137: 288–293, https://doi.org/10.1093/brain/awt311
20. Griffin D.R. (1958), Listening in the Dark: The Acoustic Orientation of Bats and Men, Yale University Press.
21. Heller L.M., Schenker A., Grover P., Gardner M. (2017), Evaluating two ways to train sensitivity to echoes to improve echolocation, [in:] The 23rd International Conference on Auditory Display (ICAD 2017), pp. 159–166, https://doi.org/10.21785/icad2017.053
22. Holmes N. (2011), An Echolocation Training Package, International Journal of Orientation & Mobility, 4(1): 84–91.
23. Kish D. (2003), Sonic Echolocation: A Modern Review and Synthesis of the Literature.
24. Kish D., Hook J. (2017), Echolocation and Flash Sonar, American Printing House.
25. Kolarik A.J., Cirstea S., Pardhan S., Moore B.C.J. (2014), A summary of research investigating echolocation abilities of blind and sighted humans, Hearing Research, 310: 60–68, https://doi.org/10.1016/j.heares.2014.01.010
26. Kolarik A.J., Moore B.C.J., Zahorik P., Cirstea S., Pardhan S. (2016), Auditory distance perception in humans: A review of cues, development, neuronal bases, and effects of sensory loss, Attention, Perception, & Psychophysics, 78(2): 373–395, https://doi.org/10.3758/s13414-015-1015-1
27. Kolarik A.J., Pardhan S., Moore B.C.J. (2021), A framework to account for the effects of visual loss on human auditory abilities, Psychological Review, 128(5): 913–935, https://doi.org/10.1037/rev0000279
28. Kolarik A.J., Scarfe A.C., Moore B.C.J., Pardhan S. (2017), Blindness enhances auditory obstacle circumvention: Assessing echolocation, sensory substitution, and visual-based navigation, PLOS ONE, 12(4): e0175750, https://doi.org/10.1371/journal.pone.0175750
29. Kritly L., Sluys Y., Pelegrín-García D., Glorieux C., Rychtarikova M. (2021), Discrimination of 2D wall textures by passive echolocation for different reflected-to-direct level difference configurations, PLOS ONE, 16(5): 10.1371/journal.pone.0251397.
30. Lessard N., Paré M., Lepore F., Lassonde M. (1998), Early-blind human subjects localize sound sources better than sighted subjects, Nature, 395: 278–280, https://doi.org/10.1038/26228
31. Milne J.L., Goodale M.A., Thaler L. (2014), The role of head movements in the discrimination of 2-D shape by blind echolocation experts, Attention, Perception, & Psychophysics, 76: 1828–1837, https://doi.org/10.3758/s13414-014-0695-2
32. Nilsson M.E., Schenkman B.N. (2016), Blind people are more sensitive than sighted people to binaural sound-location cues, particularly inter-aural level differences, Hearing Research, 332: 223–232, https://doi.org/10.1016/j.heares.2015.09.012
33. Norman L.J., Dodsworth C., Foresteire D., Thaler L. (2021), Human click-based echolocation: Effects of blindness and age, and real-life implications in a 10-week training program, PLOS ONE, 16(6): e0252330, https://doi.org/10.1371/journal.pone.0252330
34. Norman L.J., Thaler L. (2018), Human echolocation for target detection is more accurate with emissions containing higher spectral frequencies, and this is explained by echo intensity, I-Perception, 9(3), https://doi.org/10.1177/2041669518776984
35. Norman L.J., Thaler L. (2020), Stimulus uncertainty affects perception in human echolocation: Timing, level, and spectrum, Journal of Experimental Psychology: General, 149(12): 2314–2331, https://doi.org/10.1037/xge0000775
36. Norman L.J., Thaler L. (2021), Perceptual constancy with a novel sensory skill, Journal of Experimental Psychology: Human Perception and Performance, 47(2): 269–281, https://doi.org/10.1037/xhp0000888
37. Rojas J.A.M., Hermosilla J.A., Montero R.S., Espí P.L.L. (2009), Physical analysis of several organic signals for human echolocation: Oral vacuum pulses, Acta Acustica United with Acustica, 95(2): 325–330, https://doi.org/10.3813/AAA.918155
38. Rosenblum L., Gordon M.S., Jarquin L. (2000), Echolocating distance by moving and stationary listeners, Ecological Psychology, 12(3): 181–206, https://doi.org/10.1207/S15326969ECO1203_1
39. Rychtarikova M., Zelem L., Kritly L., Garcia D.P., Chmelík V., Glorieux C. (2017), Auditory recognition of surface texture with various scattering coefficients, The Journal of the Acoustical Society of America, 141(5): 3452–3452, https://doi.org/10.1121/1.4987157
40. Schenkman B.N., Gidla V.K. (2020), Detection, thresholds of human echolocation in static situations for distance, pitch, loudness and sharpness, Applied Acoustics, 163: 107214, https://doi.org/10.1016/j.apacoust.2020.107214
41. Schenkman B.N., Jansson G. (1986), The detection and localization of objects by the blind with the aid of long-cane tapping sounds, Human Factors, 28(5): 607–618.
42. Schenkman B.N., Nilsson M., Grbic N. (2016), Human echolocation: Acoustic gaze for burst trains and continuous noise, Applied Acoustics, 106: 77–86, https://doi.org/10.1016/j.apacoust.2015.12.008
43. Schenkman B.N., Nilsson M.E. (2010), Human echolocation: Blind and sighted persons’ ability to detect sounds recorded in the presence of a reflecting object, Perception, 39(4): 483–501, https://doi.org/10.1068/p6473
44. Schenkman B.N., Nilsson M.E. (2011), Human echolocation: Pitch versus loudness information, Perception, 40(7): 840–852, https://doi.org/10.1068/p6898
45. Schörnich S., Nagy A., Wiegrebe L. (2012), Discovering your inner bat: Echo-acoustic target ranging in humans, Journal of the Association for Research in Otolaryngology: JARO, 13(5): 673–682, https://doi.org/10.1007/s10162-012-0338-z
46. Smith G.E., Baker C.J. (2012), Human echolocation waveform analysis, [in:] IET International Conference on Radar Systems (Radar 2012), https://doi.org/10.1049/cp.2012.1595
47. Stock R. (2022), Hearing echoes as an audile technique, [in:] Schillmeier M., Stock R., Ochsner B. [Eds.], Techniques of Hearing. History, Theory and Practices, pp. 55–65, Routledge, https://doi.org/10.4324/9781003150763-6
48. Supa M., Cotzin M., Dallenbach K.M. (1944), “Facial vision”: The perception of obstacles by the blind, The American Journal of Psychology, 57(2): 133–183, https://doi.org/10.2307/1416946
49. Teng S., Whitney D. (2011), The acuity of echolocation: Spatial resolution in the sighted compared to expert performance, Journal of Visual Impairment & Blindness, 105(1): 20–32.
50. Thaler L. et al. (2017), Mouth-clicks used by blind expert human echolocators – signal description and model based signal synthesis, PLOS Computational Biology, 13(8): e1005670, https://doi.org/10.1371/journal.pcbi.1005670
51. Thaler L., Antoniou M., Zhang X., Kish D. (2020a), The flexible action system: Click-based echolocation may replace certain visual functionality for adaptive walking, Journal of Experimental Psychology: Human Perception and Performance, 46(1): 21–35, https://doi.org/10.1037/xhp0000697
52. Thaler L., Arnott S.R., Goodale M.A. (2011), Neural correlates of natural human echolocation in early and late blind echolocation experts, PLOS ONE, 6(5): e20162, https://doi.org/10.1371/journal.pone.0020162
53. Thaler L., Castillo-Serrano J. (2016), People’s ability to detect objects using click-based echolocation: A direct comparison between mouth-clicks and clicks made by a loudspeaker, PLOS ONE, 11(5): e0154868, https://doi.org/10.1371/journal.pone.0154868
54. Thaler L., De Vos H.P.J.C., Kish D., Antoniou M., Baker C.J., Hornikx M.C.J. (2019), Human click-based echolocation of distance: Superfine acuity and dynamic clicking behaviour, Journal of the Association for Research in Otolaryngology, JARO, 20(5): 499–510, https://doi.org/10.1007/s10162-019-00728-0
55. Thaler L., De Vos R., Kish D., Antoniou M., Baker C., Hornikx M. (2018), Human echolocators adjust loudness and number of clicks for detection of reflectors at various azimuth angles, Proceedings of the Royal Society B: Biological Sciences, 285(1873): 20172735, https://doi.org/10.1098/rspb.2017.2735
56. Thaler L., Foresteire D. (2017), Visual sensory stimulation interferes with people’s ability to echolocate object size, Scientific Reports, 7(1): 13069, https://doi.org/10.1038/s41598-017-12967-3
57. Thaler L., Goodale M.A. (2016), Echolocation in humans: An overview, WIREs Cognitive Science, 7(6): 382–393, https://doi.org/10.1002/wcs.1408
58. Thaler L., Zhang X., Antoniou M., Kish D.C., Cowie D. (2020b), The flexible action system: Click-based echolocation may replace certain visual functionality for adaptive walking, Journal of Experimental Psychology: Human Perception and Performance, 46(1): 21–35, https://doi.org/10.1037/xhp0000697
59. Tirado C., Gerdfeldter B., Kärnekull S.C., Nilsson M.E. (2021), Comparing echo-detection and echo-localization in sighted individuals, Perception, 50(4): 308–327, https://doi.org/10.1177/03010066211000617
60. Tirado C., Lundén P., Nilsson M.E. (2019), The Echobot: An automated system for stimulus presentation in studies of human echolocation, PLOS ONE, 14(10): e0223327, https://doi.org/10.1371/journal.pone.0223327
61. Tonelli A., Brayda L., Gori M. (2016), Depth echolocation learnt by novice sighted people, PLOS ONE, 11(6): e0156654, https://doi.org/10.1371/journal.pone.0156654
62. Tonelli A., Campus C., Brayda L. (2018), How body motion influences echolocation while walking, Scientific Reports, 8(1): 15704, https://doi.org/10.1038/s41598-018-34074-7
63. Tonelli A., Campus C., Gori M. (2020), Early visual cortex response for sound in expert blind echolocators, but not in early blind non-echolocators, Neuropsychologia, 147: 107617, https://doi.org/10.1016/j.neuropsychologia.2020.107617
64. van de Schoot R., Miocevic M. [Eds.] (2020), Small Sample Size Solutions a Guide for Applied Researchers and Practitioners, Routledge, https://doi.org/10.4324/9780429273872
65. Vercillo T., Milne J.L., Gori M., Goodale M.A. (2014), Enhanced auditory spatial localization in blind echolocators, Neuropsychologia, 67: 35–40, https://doi.org/10.1016/j.neuropsychologia.2014.12.0
66. Voss P., Lassonde M., Gougoux F., Fortin M., Guillemot J.-P., Lepore F. (2004), Early- and late-onset blind individuals show supra-normal auditory abilities in far-space, Current Biology, 14(19): 1734–1738, https://doi.org/10.1016/j.cub.2004.09.051
67. Wallmeier L., Wiegrebe L. (2014), Ranging in human sonar: Effects of additional early reflections and exploratory head movements, PLOS ONE, 9(12): e115363, https://doi.org/10.1371/journal.pone.0115363
2. Andrade R., Waycott J., Baker S., Veterie F. (2021), Echolocation as a means for people with visual impairment (PVI) to acquire spatial knowledge of virtual space, ACM Transactions on Accessible Computing, 14(1): 1–25, https://doi.org/10.1145/3448273
3. Arias C., Bermejo F., Hüg M.X., Venturelli N., Rabinovich D., Skarp A.O. (2012), Echolocation: An action-perception phenomenon, New Zealand Acoustics, 25(2): 20–27.
4. Arias C., Ramos O.A. (1997), Psychoacoustic tests for the study of human echolocation ability, Applied Acoustics, 51(4): 399–419, https://doi.org/10.1016/S0003-682X%2897%2900010-8
5. Bogus M., Bujacz M. (2021), Analysis of mouth click sounds used in echolocation, [in:] 2021 Signal Processing Symposium (SPSympo), pp. 23–25, https://doi.org/10.1109/SPSympo51155.2020.9593698
6. Bujacz M. et al. (2018), EchoVis: Training echolocation using binaural recordings – Initial benchmark results, [in:] Computers Helping People with Special Needs. ICCHP 2018. Lecture Notes in Computer Science, Miesenberger K., Kouroupetroglou G. [Eds.], Vol. 10897, pp. 102–109, https://doi.org/10.1007/978-3-319-94274-2_15
7. Bujacz M., Górski G., Matysik K. (2021), Mobile game development with spatially generated reverberation sound, [in:] Advances in Systems Engineering. ICSEng 2021. Lecture Notes in Networks and Systems, Borzemski L., Selvaraj H., Swiatek J. [Eds.], Vol. 364, pp. 69–78, Springer, https://doi.org/10.1007/978-3-030-92604-5_7
8. Bujacz M., Królak A., Górski G., Matysik K., Witek P. (2022a), Echovis – A collection of human echolocation tests performed by blind and sighted individuals: A pilot study, British Journal of Visual Impairment.
9. Bujacz M., Skulimowski P., Królak A., Sztyler B., Strumiłło P. (2022b), Comparison of echolocation abilities of blind and normally sighted humans using different source sounds, Vibrations in Physical Systems, 33(2), https://doi.org/10.21008/j.0860-6897.2022.2.13
10. Castillo-Serrano J.G., Norman L.J., Foresteire D., Thaler L. (2021), Increased emission intensity can compensate for the presence of noise in human click-based echolocation, Scientific Reports, 11: 1750, https://doi.org/10.1038/s41598-021-81220-9
11. Cooper S., Velazco P., Schantz H. (2020), Navigating in darkness: Human echolocation with comments on bat echolocation, Journal of the Human Anatomy and Physiology Society, 24(2): 36–41, https://doi.org/10.21692/haps.2020.016
12. Corder G.W., Foreman D.I. (2009), Nonparametric Statistics for Non-Statisticians: A Step-by-Step Approach, John Wiley & Sons, Inc.
13. Dobrucki A., Plaskota P., Pruchnicki P., Pec M., Bujacz M., Strumiłło P. (2010). Measurement system for personalized head-related transfer functions and its verification by virtual source localization trials with visually impaired and sighted individuals, Journal of The Audio Engineering Society, 58(9): 724–738.
14. Dodsworth C., Norman L.J., Thaler L. (2020), Navigation and perception of spatial layout in virtual echo-acoustic space, Cognition, 197: 104185, https://doi.org/10.1016/j.cognition.2020.104185
15. Ekkel M.R., van Lier R., Steenbergen B. (2017), Learning to echolocate in sighted people: A correlational study on attention, working memory and spatial abilities, Experimental Brain Research, 235: 809–818, https://doi.org/10.1007/s00221-016-4833-z
16. Fiehler K., Schütz I., Meller T., Thaler L. (2015), Neural correlates of human echolocation of path direction during walking, Multisensory Research, 28(1–2): 195–226, https://doi.org/10.1163/22134808-00002491
17. Flanagin V.L. et al. (2017), Human exploration of enclosed spaces through echolocation, Journal of Neuroscience, 37(6): 1614–1627, https://doi.org/10.1523/JNEUROSCI.1566-12.2016
18. Fundacja Instytut Rozwoju Regionalnego [FIRR] (2019), Training Curriculum. Active Echolocation for People with Visual Impairment.
19. Gori M., Sandini G., Martinoli C., Burr D.C. (2014), Impairment of auditory spatial localization in congenitally blind human subjects, Brain: A Journal of Neurology, 137: 288–293, https://doi.org/10.1093/brain/awt311
20. Griffin D.R. (1958), Listening in the Dark: The Acoustic Orientation of Bats and Men, Yale University Press.
21. Heller L.M., Schenker A., Grover P., Gardner M. (2017), Evaluating two ways to train sensitivity to echoes to improve echolocation, [in:] The 23rd International Conference on Auditory Display (ICAD 2017), pp. 159–166, https://doi.org/10.21785/icad2017.053
22. Holmes N. (2011), An Echolocation Training Package, International Journal of Orientation & Mobility, 4(1): 84–91.
23. Kish D. (2003), Sonic Echolocation: A Modern Review and Synthesis of the Literature.
24. Kish D., Hook J. (2017), Echolocation and Flash Sonar, American Printing House.
25. Kolarik A.J., Cirstea S., Pardhan S., Moore B.C.J. (2014), A summary of research investigating echolocation abilities of blind and sighted humans, Hearing Research, 310: 60–68, https://doi.org/10.1016/j.heares.2014.01.010
26. Kolarik A.J., Moore B.C.J., Zahorik P., Cirstea S., Pardhan S. (2016), Auditory distance perception in humans: A review of cues, development, neuronal bases, and effects of sensory loss, Attention, Perception, & Psychophysics, 78(2): 373–395, https://doi.org/10.3758/s13414-015-1015-1
27. Kolarik A.J., Pardhan S., Moore B.C.J. (2021), A framework to account for the effects of visual loss on human auditory abilities, Psychological Review, 128(5): 913–935, https://doi.org/10.1037/rev0000279
28. Kolarik A.J., Scarfe A.C., Moore B.C.J., Pardhan S. (2017), Blindness enhances auditory obstacle circumvention: Assessing echolocation, sensory substitution, and visual-based navigation, PLOS ONE, 12(4): e0175750, https://doi.org/10.1371/journal.pone.0175750
29. Kritly L., Sluys Y., Pelegrín-García D., Glorieux C., Rychtarikova M. (2021), Discrimination of 2D wall textures by passive echolocation for different reflected-to-direct level difference configurations, PLOS ONE, 16(5): 10.1371/journal.pone.0251397.
30. Lessard N., Paré M., Lepore F., Lassonde M. (1998), Early-blind human subjects localize sound sources better than sighted subjects, Nature, 395: 278–280, https://doi.org/10.1038/26228
31. Milne J.L., Goodale M.A., Thaler L. (2014), The role of head movements in the discrimination of 2-D shape by blind echolocation experts, Attention, Perception, & Psychophysics, 76: 1828–1837, https://doi.org/10.3758/s13414-014-0695-2
32. Nilsson M.E., Schenkman B.N. (2016), Blind people are more sensitive than sighted people to binaural sound-location cues, particularly inter-aural level differences, Hearing Research, 332: 223–232, https://doi.org/10.1016/j.heares.2015.09.012
33. Norman L.J., Dodsworth C., Foresteire D., Thaler L. (2021), Human click-based echolocation: Effects of blindness and age, and real-life implications in a 10-week training program, PLOS ONE, 16(6): e0252330, https://doi.org/10.1371/journal.pone.0252330
34. Norman L.J., Thaler L. (2018), Human echolocation for target detection is more accurate with emissions containing higher spectral frequencies, and this is explained by echo intensity, I-Perception, 9(3), https://doi.org/10.1177/2041669518776984
35. Norman L.J., Thaler L. (2020), Stimulus uncertainty affects perception in human echolocation: Timing, level, and spectrum, Journal of Experimental Psychology: General, 149(12): 2314–2331, https://doi.org/10.1037/xge0000775
36. Norman L.J., Thaler L. (2021), Perceptual constancy with a novel sensory skill, Journal of Experimental Psychology: Human Perception and Performance, 47(2): 269–281, https://doi.org/10.1037/xhp0000888
37. Rojas J.A.M., Hermosilla J.A., Montero R.S., Espí P.L.L. (2009), Physical analysis of several organic signals for human echolocation: Oral vacuum pulses, Acta Acustica United with Acustica, 95(2): 325–330, https://doi.org/10.3813/AAA.918155
38. Rosenblum L., Gordon M.S., Jarquin L. (2000), Echolocating distance by moving and stationary listeners, Ecological Psychology, 12(3): 181–206, https://doi.org/10.1207/S15326969ECO1203_1
39. Rychtarikova M., Zelem L., Kritly L., Garcia D.P., Chmelík V., Glorieux C. (2017), Auditory recognition of surface texture with various scattering coefficients, The Journal of the Acoustical Society of America, 141(5): 3452–3452, https://doi.org/10.1121/1.4987157
40. Schenkman B.N., Gidla V.K. (2020), Detection, thresholds of human echolocation in static situations for distance, pitch, loudness and sharpness, Applied Acoustics, 163: 107214, https://doi.org/10.1016/j.apacoust.2020.107214
41. Schenkman B.N., Jansson G. (1986), The detection and localization of objects by the blind with the aid of long-cane tapping sounds, Human Factors, 28(5): 607–618.
42. Schenkman B.N., Nilsson M., Grbic N. (2016), Human echolocation: Acoustic gaze for burst trains and continuous noise, Applied Acoustics, 106: 77–86, https://doi.org/10.1016/j.apacoust.2015.12.008
43. Schenkman B.N., Nilsson M.E. (2010), Human echolocation: Blind and sighted persons’ ability to detect sounds recorded in the presence of a reflecting object, Perception, 39(4): 483–501, https://doi.org/10.1068/p6473
44. Schenkman B.N., Nilsson M.E. (2011), Human echolocation: Pitch versus loudness information, Perception, 40(7): 840–852, https://doi.org/10.1068/p6898
45. Schörnich S., Nagy A., Wiegrebe L. (2012), Discovering your inner bat: Echo-acoustic target ranging in humans, Journal of the Association for Research in Otolaryngology: JARO, 13(5): 673–682, https://doi.org/10.1007/s10162-012-0338-z
46. Smith G.E., Baker C.J. (2012), Human echolocation waveform analysis, [in:] IET International Conference on Radar Systems (Radar 2012), https://doi.org/10.1049/cp.2012.1595
47. Stock R. (2022), Hearing echoes as an audile technique, [in:] Schillmeier M., Stock R., Ochsner B. [Eds.], Techniques of Hearing. History, Theory and Practices, pp. 55–65, Routledge, https://doi.org/10.4324/9781003150763-6
48. Supa M., Cotzin M., Dallenbach K.M. (1944), “Facial vision”: The perception of obstacles by the blind, The American Journal of Psychology, 57(2): 133–183, https://doi.org/10.2307/1416946
49. Teng S., Whitney D. (2011), The acuity of echolocation: Spatial resolution in the sighted compared to expert performance, Journal of Visual Impairment & Blindness, 105(1): 20–32.
50. Thaler L. et al. (2017), Mouth-clicks used by blind expert human echolocators – signal description and model based signal synthesis, PLOS Computational Biology, 13(8): e1005670, https://doi.org/10.1371/journal.pcbi.1005670
51. Thaler L., Antoniou M., Zhang X., Kish D. (2020a), The flexible action system: Click-based echolocation may replace certain visual functionality for adaptive walking, Journal of Experimental Psychology: Human Perception and Performance, 46(1): 21–35, https://doi.org/10.1037/xhp0000697
52. Thaler L., Arnott S.R., Goodale M.A. (2011), Neural correlates of natural human echolocation in early and late blind echolocation experts, PLOS ONE, 6(5): e20162, https://doi.org/10.1371/journal.pone.0020162
53. Thaler L., Castillo-Serrano J. (2016), People’s ability to detect objects using click-based echolocation: A direct comparison between mouth-clicks and clicks made by a loudspeaker, PLOS ONE, 11(5): e0154868, https://doi.org/10.1371/journal.pone.0154868
54. Thaler L., De Vos H.P.J.C., Kish D., Antoniou M., Baker C.J., Hornikx M.C.J. (2019), Human click-based echolocation of distance: Superfine acuity and dynamic clicking behaviour, Journal of the Association for Research in Otolaryngology, JARO, 20(5): 499–510, https://doi.org/10.1007/s10162-019-00728-0
55. Thaler L., De Vos R., Kish D., Antoniou M., Baker C., Hornikx M. (2018), Human echolocators adjust loudness and number of clicks for detection of reflectors at various azimuth angles, Proceedings of the Royal Society B: Biological Sciences, 285(1873): 20172735, https://doi.org/10.1098/rspb.2017.2735
56. Thaler L., Foresteire D. (2017), Visual sensory stimulation interferes with people’s ability to echolocate object size, Scientific Reports, 7(1): 13069, https://doi.org/10.1038/s41598-017-12967-3
57. Thaler L., Goodale M.A. (2016), Echolocation in humans: An overview, WIREs Cognitive Science, 7(6): 382–393, https://doi.org/10.1002/wcs.1408
58. Thaler L., Zhang X., Antoniou M., Kish D.C., Cowie D. (2020b), The flexible action system: Click-based echolocation may replace certain visual functionality for adaptive walking, Journal of Experimental Psychology: Human Perception and Performance, 46(1): 21–35, https://doi.org/10.1037/xhp0000697
59. Tirado C., Gerdfeldter B., Kärnekull S.C., Nilsson M.E. (2021), Comparing echo-detection and echo-localization in sighted individuals, Perception, 50(4): 308–327, https://doi.org/10.1177/03010066211000617
60. Tirado C., Lundén P., Nilsson M.E. (2019), The Echobot: An automated system for stimulus presentation in studies of human echolocation, PLOS ONE, 14(10): e0223327, https://doi.org/10.1371/journal.pone.0223327
61. Tonelli A., Brayda L., Gori M. (2016), Depth echolocation learnt by novice sighted people, PLOS ONE, 11(6): e0156654, https://doi.org/10.1371/journal.pone.0156654
62. Tonelli A., Campus C., Brayda L. (2018), How body motion influences echolocation while walking, Scientific Reports, 8(1): 15704, https://doi.org/10.1038/s41598-018-34074-7
63. Tonelli A., Campus C., Gori M. (2020), Early visual cortex response for sound in expert blind echolocators, but not in early blind non-echolocators, Neuropsychologia, 147: 107617, https://doi.org/10.1016/j.neuropsychologia.2020.107617
64. van de Schoot R., Miocevic M. [Eds.] (2020), Small Sample Size Solutions a Guide for Applied Researchers and Practitioners, Routledge, https://doi.org/10.4324/9780429273872
65. Vercillo T., Milne J.L., Gori M., Goodale M.A. (2014), Enhanced auditory spatial localization in blind echolocators, Neuropsychologia, 67: 35–40, https://doi.org/10.1016/j.neuropsychologia.2014.12.0
66. Voss P., Lassonde M., Gougoux F., Fortin M., Guillemot J.-P., Lepore F. (2004), Early- and late-onset blind individuals show supra-normal auditory abilities in far-space, Current Biology, 14(19): 1734–1738, https://doi.org/10.1016/j.cub.2004.09.051
67. Wallmeier L., Wiegrebe L. (2014), Ranging in human sonar: Effects of additional early reflections and exploratory head movements, PLOS ONE, 9(12): e115363, https://doi.org/10.1371/journal.pone.0115363
