Localization of Acoustic Signals Used in Sound Emitters at Pedestrian Crosswalks
M. Niewiarowicza and A. Furmannb
aDepartment of Otolaryngology, Poznań University of Medical Sciences, Przybyszewskiego 49, 60-355 Poznań, Poland
bInstitute of Acoustics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań, Poland
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This study aimed at determining an optimal acoustic signal, which could be used in sound emitters at blind and visually impaired enabled pedestrian crosswalks. Two signals were identified from among groups of tested signals on the basis of psychoacoustic tests. These two signals met the following standard requirements: TR signal - a signal with a triangular temporal envelope and a sinusoidal carrier and RC signal - a signal with a rectangular temporal envelope and a rectangular carrier, both with a basic frequency of 880 Hz, repeated periodically with a frequency of 5 Hz. The ability to localize was tested by a modified method of angle of directional hearing acuity in which the two alternative forced choice adaptation procedure was used. The test signals were emitted against the background of traffic noise and the ratio of the useful signal (65 dB SPL) to noise (75 dB SPL) was (-10 dB). The tests were conducted on 8 subjects with normal hearing (5 women and 3 men), aged 22-37 years. Following statistical analysis it was found that: individual subjects' responses differed considerably with respect to angle of direction hearing acuity values, localization is most difficult at the angles of 90° and 270°, worse localization for trams noise were stated, RC signals are better localized than TR signals.
DOI: 10.12693/APhysPolA.121.A-9
PACS numbers: 43.66.Qp