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speech were significantly larger than in both adult- [F(1,10) ϭ 7.63, P Ͻ 0.005] and pet- directed speech [F(1,10) ϭ 10.98, P Ͻ 0.001]but did not differ between pet- and adult-directed speech [F(1,10) ϭ 0.19, P Ͼ 0.05] (see supple-mentary text).
These results show that infant- and pet-di- Denis Burnham,1* Christine Kitamura,1 Ute´ Vollmer-Conna2 rected speech are similar and distinctly differentfrom adult-directed speech in terms of height-ened pitch and affect. Interestingly, only infant- When talking to babies, adults invariably use a the words cannot be understood; and (iii) vowel special speech register characterized by elevated hyperarticulation, which is objectified by plotting vowels. Thus, vowel hyperarticulation does not fundamental frequency ( pitch), exaggerated into- first and second formant (F and F ) values of the accompany special registers simply because they nation contours, and high affect (1, 2). It has also “corner” vowels, /i/, /u/, and /a/, and comparing differ from adult speech in pitch and affect.
been found that mothers hyperarticulate vowels the resultant vowel triangles (3).
Rather, it seems to be a didactic device: Mothers when addressing their infants but not when Speech samples of the mothers, all monolin- exaggerate their vowels for their infants but not speaking to other adults (3). This phenomenon is gual native speakers of Australian English, were ubiquitous, occurring across various languages— recorded on a portable Professional Walkman Evidently, speakers are sensitive to their au- English, Russian, Swedish, and Japanese (3, 4)— (Sony) with lapel microphone left with the moth- dience, both in regard to acoustic preferences and is thought to facilitate infants’ linguistic de- ers in their homes. To obtain the requisite corner and emotional needs, and in terms of potential velopment by amplifying the phonetic character- vowel information, we asked mothers to play linguistic ability. We might predict that for- istics of native language vowels (3). However, with and name three provided toys, a “sheep,” a eigner-directed speech would have hyperar- the very ubiquity of this speech style means that “shoe,” and a “shark,” in naturalistic 10- to ticulated vowels but little elevation of emo- it is practically impossible to obtain direct evi- 15-min interactions with each recipient. Mothers dence of its function as a language-teaching de- made separate recordings in their own time talk- differences within speech registers; there may ticulation in parrot-directed speech.
propose that (i) specialspeech registers differin their mix of acous-tic, affective, and vow-el perceive the emotionaland linguistic needs of Fig. 1. (A) Pitch (fundamental frequency in hertz), (B) rated affect, and (C) vowel hyperarticulation (in F1-F2 vowel space) in
infant-, pet-, and adult-directed speech (IDS, PDS, and ADS, respectively).
vice; clearly, we cannot ask caregivers not to use ing to their 6-month-old infant, to their pet cat or their mix of speech components accordingly.
baby-talk with infants, as it appears to be elicited dog, and to another adult (see supplementary text automatically. So, as the nature of the speech References and Notes
1. A. Fernald, P. K. Kuhl, Infant Behav. Dev. 10, 279 (1987).
input cannot be changed, we decided to approach 2. C. Kitamura, D. Burnham, in Advances in Infancy this issue from another angle— by experimental- pitch, affect, and vowel triangles to test differ- Research, vol. 12, C. Rovee-Collier, Ed. (Ablex, Nor- ly manipulating the nature of the recipients.
ences in infant-, pet-, and adult-directed speech 3. P. K. Kuhl et al., Science 277, 684 (1997).
The uncanny similarity of pet- to infant-di- (no differences were found in speech to the five 4. J. E. Andruski, P. K. Kuhl, A. Hayashi, J. Acoust. Soc. rected speech has been noted previously (5), al- cats and seven dogs). For pitch (Fig. 1A), infant- Am. 105, 1095 (1999).
though no objective comparison of either pitch or and pet-directed speech was statistically equiva- 5. K. Hirsh-Pasek, R. Treiman, J. Child Lang. 9, 229 (1982).
6. We thank V. Averkiou, A. Olley, M. Nguyen, and C.
affective speech components has been attempted.
lent [F(1,11) ϭ 0.03, P Ͼ 0.05], but pitch in Paterson for acoustic and ratings data collection; N.
Does this similarity between pet- and infant- speech to both infants [F(1,11) ϭ 6.58, P Ͻ 0.05] Yates-Goozee for phonetic analyses; T. Burnham and S.
directed speech imply that vowel hyperarticula- and pets [F(1,11) ϭ 36.52, P Ͻ 0.001] was Vollmer-Conna for hypothesis development; and D.
Hadzi-Pavlovic, K. Bird, and J. Wolfe for statistical advice.
tion also occurs when we talk to our pets? Are we significantly higher than pitch in speech to adults.
( perhaps unconsciously) trying to teach our ani- Ratings of low-pass–filtered speech (see Au- Supporting Online Material
www.sciencemag.org/cgi/content/full/296/5572/ mals how to speak or at least understand our dio S1, S2, and S3) on five scales were factor language? Or maybe vowel hyperarticulation is analyzed, and scores from the resultant affect simply a by-product of the highly emotional factor were derived. Affect was greater in in- Audio clips (Audio 1, Audio 2, and Audio 3) speech we use to both our infants and pets.
fant- than in pet-directed speech [F(1,11) ϭ To resolve this issue, we made objective com- 10.76, P Ͻ 0.01], but affect in both infant- parisons of 12 mothers’ speech to their infant, [F(1,11) ϭ 94.34, P Ͻ 0.001] and pet-directed 1MARCS Auditory Laboratories, University of Western their pet, and another adult in three domains: (i) speech [F(1,11) ϭ 54.44, P Ͻ 0.001] was high- Sydney, Post Office Box 1797, Sydney, 1797, Australia.
pitch, which is the psychological correlate of er than in adult-directed speech (Fig. 1B).
2School of Psychiatry, Department of Human Behaviour, University of New South Wales, UNSW Sydney 2052, fundamental frequency; (ii) affect, which is mea- Vowels for infant-, pet-, and adult-directed sured by ratings of low-pass–filtered speech, in speech are plotted in F -F space in Fig. 1C.
*To whom correspondence should be addressed. E- which the intonation and rhythm can be heard but Mothers’ vowel triangle areas in infant-directed www.sciencemag.org SCIENCE VOL 296 24 MAY 2002

Source: https://quote.ucsd.edu/cogs101b/files/2013/01/burnham.pdf