CRITICAL BANDS AND CRITICAL-RATIO BANDWIDTH IN THE EUROPEAN STARLING

Critical bands (CB) and critical-ratio (CR) bandwidth were determined in five European starlings (Stumus vulgaris) using a GO/NOGO procedure and the method of constant stimuli. Test-tone frequencies were 1, 2, 4, and 6.3 kHz. Critical ratios were independent of the level of the w hite noise masker. The lowest CR of 21.8 dB was found at 1 kHz, and th e CR monotonically increased on average by 2.3 dB per octave. CR-bandw idths at a masker spectrum level of 41 dB were 151, 191, 437, and 501 Hz at 1, 2, 4, and 6.3 Mit, respectively. With the exception of the te st-tone frequency of 6.3 kHz, the size of the critical bands measured with a band-narrowing procedure was similar to that of the CR-bandwidt h. CBs were 135, 233, 345, and 1156 Hz at 1, 2, 4, and 6.3 kHz, respec tively. A repeat measurement at 6.3 kHz with another speaker position yielded a CB of 860 Hz. The results of this psychoacoustic study in th e starling are discussed with respect to comparative data from other v ertebrates and to neurophysiological bandwidth measurements of tuning curves of auditory-nerve fibres.