Vowel-Like Sound Structure in an African Grey Parrot (Psittacus erithacus) Vocal Production

In our study we taught a female African Grey 11 Italian words: vowel-like sounds were extracted from comprehensible words after critical listening, and pitch frequency (Pkf) was measured for the first three formants of each vowel. Similarly, formants from human vowels were isolated and measured. The analysis run on formant frequencies mean values of both samples revealed that human vowels could be separated on the basis of the first three formants. Comparison between each human vowel and its parrot counterpart revealed that four out of five parrot vowels could be considered statistically different from human ones regarding the first two formants, but comparison between F2/F1 and F3/F2 are not significant. Our results suggest that formant spaces do exist in the vocalic production of a talking bird. This leads to interesting conclusions about generalization skills involved in speech recognition, vowel parsing patterns and label production.