Critical bands and critical-ratio bandwidth in the European starling.

Critical bands (CB) and critical-ratio (CR) bandwidth were determined in five European starlings (Sturnus 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 white noise masker. The lowest CR of 21.8 dB was found at 1 kHz, and the CR monotonically increased on average by 2.3 dB per octave. CR-bandwidths at a masker spectrum level of 41 dB were 151, 191, 437, and 501 Hz at 1, 2, 4, and 6.3 kHz, respectively. With the exception of the test-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-bandwidth. CBs were 135, 233, 345, and 1156 Hz at 1, 2, 4, and 6.3 kHz, respectively. A repeat measurement at 6.3 kHz with another speaker position yielded a CB of 860 Hz. The results of this psychoacoustic study in the starling are discussed with respect to comparative data from other vertebrates and to neurophysiological bandwidth measurements of tuning curves of auditory-nerve fibres.