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Review of Methodologies in Recent Research of Human Echolocation

Bujacz Michał, Sztyler Bartłomiej, Wileńska Natalia, Czajkowska Karolina, Strumiłło Paweł

Archives of Acoustics

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2023

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Vol. 48, No. 2

249--271

EN

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.

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Comparison of echolocation abilities of blind and normally sighted humans using different source sounds

Bujacz Michał, Skulimowski Piotr, Królak Aleksandra, Sztyler Bartłomiej, Strumiłło Paweł

Vibrations in Physical Systems

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2022

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Vol. 33, nr 2

art. no. 2022213

EN

The ability of some humans to echolocate has become widely known primarily due to a small number of famous expert echolocators who are capable of extraordinary feats. However, a lesser-known fact is that all humans exhibit this skill unconsciously and can learn it relatively quickly and implicitly through repeated practice. In our experiments we tested groups of 12 blind and 14 sighted untrained participants in a simple echolocation test - localizing a 1m x 2m vertical wall at distances between 1 and 3 meters using 10 different types of sounds as the source signals for the echolocation attempts. There were significant differences between the participant groups and between some of the tested sounds. Although the groups were small, a clear difference was also observed between the experienced totally blind participants and the legally blind visually impaired participants that had residual light sensitivity. From the compared sounds 3 kHz and 4 kHz synthetic percussion sounds, pink and blue noise were among the sources that led to the highest chances of correctly guessing the obstacle’s direction and distance.

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Acoustic Metamaterials

Sztyler Bartłomiej, Strumiłło Paweł

Archives of Acoustics

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2022

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Vol. 47, No. 1

3--14

EN

This review article is concerned with metamaterials, i.e. specifically engineered structures with special properties for interaction with sounds. The research on and practical design of these materials have gained momentum in the last decade, when 3D printing techniques provided the possibility to fabricate such geometrically complex structures. We briefly describe the history of research on AMMs and group them into active and passive metamaterials. For each of these groups of AMMs, we discuss the most notable construction achievements and outline the main applications. We conclude this review with a discussion of possible directions for further research and main applications of AMMs such as noise attenuation, acoustic lens, and the cloaking phenomenon.