Behavioral sensitivity to interaural difference cues in the budgerigar ( Melopsittacus undulatus )

• Published in: The Journal of the Acoustical Society of America 2010-03, Vol.127 (3_Supplement), p.1894-1894
• Main Authors: Welch, Thomas E., Garcia, Kristen, Dent, Micheal L.
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.3384730

Interaural time and level differences cues (ITDs and ILDs) allow organisms to localize sounds and detect and discriminate signals in noise. Behavioral sensitivity to these important cues has only been studied in humans and a few species of animals. Although the abilities of budgerigars to localize, detect, and discriminate a variety of sounds in quiet or noisy conditions are well known, this is the first study to equip birds with headphones so that their sensitivity to ITDs and ILDs can be measured using lateralization procedures. In one experiment, thresholds are measured behaviorally in budgerigars using pure tones (0.5–8 kHz) and broad-band noise as stimuli in a two-alternative (left-right) identification task. In another experiment, sensitivity to changes in ITDs and ILDs of binaural sounds within a repeating background (discrimination task) is measured using the same stimuli as the first experiment. Budgerigars appear to be less sensitive than humans to both ITDs and ILDs, but similar to cats and monkeys. Overall, these lateralization results are generally consistent with the free-field localization abilities of these birds, but their relatively acute sensitivity to interaural difference cues adds support to the idea that budgerigars may be using their connected interaural pathways to enhance directional hearing.