Thresholds for detection of a change in the displacement, velocity, and acceleration of a synthesized sound-emitting source
Wen Wang, Robert A. Lutfi · The Journal of the Acoustical Society of America · 1994
An experiment was conducted to determine if listeners, when judging the velocity and acceleration of a sound-emitting source, merely infer these quantities from overall source displacement. The acoustic waveform of a high-velocity source was reconstructed over headphones using principles of sound radiation and propagation from the moving source, an interaural time difference method, and a diffraction model of a spherical head. An adaptive 2IFC procedure was used to measure thresholds for detection of a change in the displacement, velocity, and acceleration of the source passing directly in front of the listener in a linear trajectory from left to right. The source traveled at 50 m/s for 4 s, at a distance of 5 m from the center of the head, point of closest approach. Thresholds for a rightward displacement showed little variability across listeners, averaging about 7 m. Velocity and acceleration thresholds varied from one listener to the next, but were in some cases less than the minimum value that could be inferred given the 7-m threshold for displacement. The results are discussed in terms of cues for discrimination related to changes in intensity, interaural delay, and Doppler effect. [Research supported by NIDCD.]