Ml. Dent et al., PERCEPTION OF SYNTHETIC L-BAR-BA-VERTICAL-BAR-VERTICAL-BAR-WA-VERTICAL-BAR SPEECH CONTINUUM BY BUDGERIGARS (MELOPSITTACUS-UNDULATUS), The Journal of the Acoustical Society of America, 102(3), 1997, pp. 1891-1897
Other than humans, extensive vocal learning has only been widely demon
strated in birds. Moreover, there are only a handful of avian species
that are known to be good mimics of human speech. One such species is
the budgerigar (Melopsittacus undulatus), which is a popular mimic of
human speech and learns new vocalizations throughout adult life. Using
operant conditioning procedures with a repeating background task, we
tested budgerigars on the discrimination of tokens from two synthetic
/ba/-/wa/ speech continua that differed in syllable, but not transitio
n, duration. Budgerigars showed a significant improvement in discrimin
ation performance on both continua near the phonetic boundary for huma
ns. Budgerigars also showed a shift in the location of the phonetic bo
undary with a change in syllable length, similar to what has been desc
ribed for humans and other primates. These results on a nonmammalian s
pecies provide support for the operation of a general, nonphonetic, au
ditory process as one mechanism which can lead to the well-known stimu
lus-length effect in humans. (C) 1997 Acoustical Society of America.