?teaang Research, 21 (1980) 279-284 © Elsevier/North-HollandBiomedical Press 279 FORWARD AND BACKWARD AUDITORY MASKING IN THE PARAKEET (MELOPSITTA CUS UNDULA TUS) ROBERT J. DOOLING and MARGARET H. SEARCY Rockefeller University, FieldResearch Center, TyrrelRoad, Millbrook, NY 12545, U.S.A. (Received 16 June 1980; accepted 27 August 1980) Backward, forward and simultaneous masking of brief tone pulses was ex~.mined in four parakeets. The pattern of non-simultaneous masking in parakeets is quite similar to that obsereed in humans with rates of threshold recovery faster for backward compared to forward masking conditions. These results may have relevance for the design of vocal signals and the coding of speei~s-spedfie information in parakeets. Key words: parakeet; backward masking; forward masking; psychophysics. INTRODUCTIOI~ There is a considerable amount of information available on temporal or non-simul. taneous masking in man [3,20]. Except for a recent study of forward ~nd backward masking in the goldfish [14], there are no comparative data from other vertebrates. The mechanisms responsible for non.simultaneous masking effects are more complex than those involved in simultaneous masking and comparative data from other vertebrates may shed light on these processes [14]. Field and laboratory studies of vocal communication in birds re~eal a richness ,. ~tem- poral structure in song rivaling that of human speech [5]. These studies have also shown that subtle changes in the temporal fine structure of vocalizations can influence both inter- and intra-species l-esponses to these sounds [4,11 ]. The temporal complexity of many avian vocalizations and the importance this complexity plays in vocal communica- tion suggests that the investigation of temporal masking effects may be of particular .interest as a step in understanding the acoustic structure of bird v0calizatiow.. To this end, the present experiment measures simultar~eous, backward and forward masking in the parakeet. METHODS Subjects were four commercially available parakeets raised in the aviaries at Rockefeller University. Two of the birds had served previously in an experiment on the detection of amplitude modulation of broad-band noise. The naive birds were about six weeks old and the experienced birds about one year old at the beginning of this experiment.