Acoustic Characteristics of Phonological Development in a Juvenile African Grey Parrot (Psittacus Erithacus) Who Is Learning Referential Speech

Abstract

Although young children can sometimes produce words in a near perfect form at a very early stage, several diary studies revealed that these correct first productions are usually followed by less faithful renditions, only to be returned later to relative accuracy. In order to investigate if this nonlinear pattern of children vocal production called “phonological regression” might also be shared with birds, we examined here the trajectory of vocal development of a young African Grey parrot (Athena) who is learning referential English. Parrots are excellent model systems for the study of speech acquisition as they possess advanced cognitive skills and are expert imitators of the human voice. By tracking Athena’s acquisition of vowel-like sounds over the course of fifteen months using audio recordings and acoustic software programs, we analyzed her vocal development over time, from her first squeaks to her more distinct pronunciations, and compared her progress with human children and other parrots in the lab. Not one, but multiple U-shaped curves characterized her acquisition of isolated labels. Our results indicate that, like human children, parrots can experience the phenomenon of phonological regression.