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

Abstract

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 F 2 /F 1 and F 3 /F 2 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.

Sounds of protolanguages: Some preliminary insights from developmental psychology

“…We know that during early development infant perception of surrounding sounds, including language, is much more advanced than motor competence (Lenti Boero 2014): infants discriminate language phonemes, sharing this capacity with many animal species: rhesus macaques, dogs, chinchilla, quails, and parrots (Adams et al 1987;Bottoni et al 2003Bottoni et al , 2009Dewson 1964;Kluender et al 1987;Kuhl and Miller 1975;Miller 1977;Morse and Snowdon 1975;Pepperberg 2007). This is a key point: why both human infants and many animal species are competent in phonemic discrimination?…”

“…Vallet et al (1997) propose an interesting model in canaries, where the ability to control singing is sexually selected as an advertiser of overall motor ability. As regards as sound imitation, we know that mammals are not able to imitate surrounding sounds; however, many birds are able to imitate surrounding sounds, including the Grey Parrot (Psytthacus erithacus) that was proposed as model for both music and language evolution (Bottoni et al 2003(Bottoni et al , 2009Pepperberg 2007).…”

Early human communication helps in understanding language evolution

“…All communication devices, human language included, imply the coevolution of both receiver and emitter, which is evident in the specialized adult language brain areas: Wernicke's and Broca's. During early development we know that infant perception of surrounding sounds, including language, is much more advanced than motor competence: Infants are capable of auditory streaming at 2–5 days old (Winkler et al 2003), and they discriminate vowel and phonetic sounds from the first month (Clarkson & Berg 1983; Eimas et al 1971; Mehler et al 1988; Teinonen et al 2009), sharing this capacity with many animal species: rhesus macaques, dogs, chinchilla, quails, and parrots (Adams et al 1987; Bottoni et al 2009; Dewson 1964; Kluender et al 1987; Kuhl & Miller 1975; Miller 1977; Morse & Snowdon 1975; Pepperberg 2007). On the melodic and musical side newborn infants recognize musical melodies heard before birth (Kisilevsky et al 2004).…”

Infant perception of atypical speech signals.

“…The second formant, F 2 , is an indication of backness, how far back the tongue position is during vowel production (Ladefoged, 2006). see Figure 1), while the first formant (F 1 ) in parrot vowels is variable and unlike human speech (Bottoni et al, 2009;Patterson & Pepperberg, 1994. Consonants, like vowels, correlate with some but not all acoustic properties of human consonants (Patterson & Pepperberg, 1998).…”

“…A comparative analysis of human and parrot vowel and stop consonant production suggests a possible basis for perceiving parrot speech-like vocalizations as speech. Vowels produced by parrots consistently yield second formants (F 2 s) 1 within the range of F 2 s produced by women and children during vowel production (Bottoni et al, 2009;Patterson & Pepperberg, 1994; 1 Vowel production is typically analyzed by means of formant structure, the resonant frequencies that define a vowel. The first formant, F 1 , reflects vowel height, or the approximate height of the tongue during production.…”