No AccessJournal of Speech, Language, and Hearing ResearchResearch Article1 Dec 2010

Lip Movement Exaggerations During Infant-Directed Speech


    Although a growing body of literature has indentified the positive effects of visual speech on speech and language learning, oral movements of infant-directed speech (IDS) have rarely been studied. This investigation used 3-dimensional motion capture technology to describe how mothers modify their lip movements when talking to their infants.


    Lip movements were recorded from 25 mothers as they spoke to their infants and other adults. Lip shapes were analyzed for differences across speaking conditions. The maximum fundamental frequency, duration, acoustic intensity, and first and second formant frequency of each vowel also were measured.


    Lip movements were significantly larger during IDS than during adult-directed speech, although the exaggerations were vowel specific. All of the vowels produced during IDS were characterized by an elevated vocal pitch and a slowed speaking rate when compared with vowels produced during adult-directed speech.


    The pattern of lip-shape exaggerations did not provide support for the hypothesis that mothers produce exemplar visual models of vowels during IDS. Future work is required to determine whether the observed increases in vertical lip aperture engender visual and acoustic enhancements that facilitate the early learning of speech.


    • Adamson, L. B., & Frick, J. E. (2003). The still face: A history of a shared experimental paradigm.Infancy, 4, 451–473.
    • Amano, S., Nakatani, T., & Kondo, T. (2006). Fundamental frequency of infants' and parents' utterances in longitudinal recordings.The Journal of the Acoustical Society of America, 119, 1636–1647.
    • Andruski, J., & Kuhl, P. K. (1996). The acoustic structure of vowels in mothers' speech to infants and children.In T. Bunnell, & W. Idsardi (Eds.), Proceedings of the Fourth International Conference on Spoken Language Processing (pp. 1545–1548). Wilmington, DE: Alfred I. du Pont Institute.
    • Beckford Wassink, A., Wright, R. A., & Franklin, A. D. (2007). Intraspeaker variability in vowel production: An investigation of motherese, hyperspeech, and Lombard speech in Jamaican speakers.Journal of Phonetics, 35, 363–379.
    • Beckman, M. E., Edwards, J., & Fletcher, J. (1992). Prosodic structure and tempo in a sonority model of articulatory dynamics.In G. J. Docherty, & D. R. Ladd (Eds.), Papers in laboratory phonology II: Segment, gesture, prosody (pp. 68–86). New York, NY: Cambridge University Press.
    • Bernstein, L. E., Takayanagi, S., & Auer, E. T., Jr. (2004). Auditory speech detection in noise enhanced by lipreading.Speech Communication, 44, 5–18.
    • Bernstein Ratner, N. (1986). Durational cues which mark clause boundaries in mother–child speech.Journal of Phonetics, 14, 303–309.
    • Bernstein Ratner, N., & Luberoff, A. (1984). Cues to post-vocalic voicing in mother–child speech.Journal of Phonetics, 12, 285–289.
    • Biringen, Z. C. (1987). Infant attention to facial expressions and facial motion.Journal of Genetic Psychology, 148, 137–133.
    • Boersma, P., & Weenink, D. (2009). Praat: Doing phonetics by computer (Version 5.1.12) [Computer program].Retrieved from
    • Brand, R. J., Baldwin, D. A., & Ashburn, L. A. (2002). Evidence for “motionese”: Modifications in mothers' infant-directed action.Developmental Science, 5, 72–83.
    • Burnham, D., Kitamura, C., & Vollmer-Conna, U. (2002, May24). What’s new, pussycat? On talking to babies and animals.Science, 296, 1435.
    • Cho, T. (2005). Prosodic strengthening and featural enhancement: Evidence from acoustic and articulatory realizations of /a,i/ in English.The Journal of the Acoustical Society of America, 117, 3867–3878.
    • Chong, S. C. F., Werker, J. F., Russell, J. A., & Carroll, J. M. (2003). Three facial expressions mothers direct to their infants.Infant and Child Development, 12, 211–232.
    • Cohn, J. F., & Elmore, M. (1988). Effect of contingent changes in mothers' affective expression on the organization of behavior in 3-month-old infants.Infant Behavior and Development, 11, 493–505.
    • DeBoer, B. (2003). Emergence of sound systems through self-organization.In C. Knight, M. Studdert-Kennedy, & J. R. Hurford (Eds.), The evolutionary emergence of language: Social function and the origins of linguistic form (pp. 177–198). Cambridge, England: Cambridge University Press.
    • Dominey, P. F., & Dodane, C. (2004). Indeterminacy in language acquisition: The role of child directed speech and joint attention.Journal of Neurolinguistics, 17, 121–145.
    • Dromey, C., & Ramig, L. O. (1998). The effect of lung volume on selected phonatory and articulatory variables.Journal of Speech, Language, and Hearing Research, 41, 491–502.
    • Edwards, J., Beckman, M. E., & Fletcher, J. (1991). Articulatory kinematics of final lengthening.The Journal of the Acoustical Society of America, 89, 369–382.
    • Englund, K., & Behne, D. (2006). Changes in infant directed speech in the first six months.Infant and Child Development, 15, 139–160.
    • Erber, N. P. (1974). Effects of angle, distance, and illumination on visual reception of speech by profoundly deaf children.Journal of Speech and Hearing Research, 17, 99–112.
    • Erickson, D. (1998). Effects of contrastive emphasis on jaw opening.Phonetica, 55, 147–169.
    • Fairbanks, G. (1950). A physiological correlative of vowel intensity.Speech Monograph, 22, 390–395.
    • Fenson, L., Dale, P., Reznick, S., Bates, E., Thal, D., & Pethick, S. (1994). Variability in early communicative development.Monographs of the Society for Research in Child Development, 59(Serial No. 242)
    • Fernald, A., & Kuhl, P. (1987). Acoustic determinants of infant preference for motherese speech.Infant Behavior and Development, 10, 279–293.
    • Fernald, A., & Simon, T. (1984). Expanded intonation contours in mothers' speech to newborns.Developmental Psychology, 20, 104–113.
    • Fernald, A., Taeschner, T., Dunn, J., Papousek, M., Boysson-Bardies, B., & Fukui, I. (1989). A cross-language study of prosodic modifications in mothers' and fathers' speech to preverbal infants.Journal of Child Language, 16, 477–501.
    • Fromkin, V. (1964). Lip positions in American English vowels.Language and Speech, 7, 215–225.
    • Goffman, L., Smith, A., Heisler, L., & Ho, M. (2008). The breadth of coarticulatory units in children and adults.Journal of Speech, Language, and Hearing Research, 51, 1424–1437.
    • Gogate, L., & Bahrick, L. E. (2001). Intersensory redundancy and seven-month-old infants' memory for arbitrary syllable–object relations.Infancy, 2, 219–231.
    • Grant, K. W., & Seitz, P. (2000). The use of visible speech cues for improving auditory detection of spoken sentences.The Journal of the Acoustical Society of America, 108, 1197–1208.
    • Grieser, D. L., & Kuhl, P. K. (1988). Maternal speech to infants in a tonal language: Support for universal prosodic features in motherese.Developmental Psychology, 24, 14–20.
    • Hall, M. D., Green, J., Moore, C. A., & Kuhl, P. K. (1999). Contribution of articulatory kinematics to visual perception of stop consonants.In P. K. Kuhl, & L. Crum (Eds.), Proceedings of the 2nd Convention of the European Acoustics Association: Forum Acusticum and 137th Meeting of the Acoustical Society of America (#4aSCb15). Woodbury, NY: Acoustical Society of America.
    • Harrington, J., Fletcher, J., & Roberts, C. (1995). Coarticulation and the accented/unaccented distinction.Journal of Phonetics, 23, 305–322.
    • Jusczyk, P., Hohne, E., & Mandel, D. (1995). Picking up regularities in the sound structure of the native language.In W. Strange (Ed.), Speech perception and linguistic experience issues in cross-language research (pp. 91–119). Timonium, MD: York Press.
    • Kaplan, P. S., Bachorowski, J.-A., Smoski, M. J., & Hudenko, W. J. (2002). Infants of depressed mothers, although competent learners, fail to learn in response to their own mother’s infant-directed speech.Psychological Science, 13, 268–271.
    • Katz, G. S., Cohn, J. F., & Moore, C. A. (1996). A combination of vocal F0 dynamic and summary features discriminates between three pragmatic categories of infant directed speech.Child Development, 67, 205–217.
    • Kemler Nelson, D., Hirsh-Pasek, K., Jusczyk, P. W., & Wright Cassidy, K. (1989). How prosodic cues in motherese might assist language learning.Journal of Child Language, 16, 53–68.
    • Kent, R. D., & Murray, A. D. (1982). Acoustic features of infant vocalic utterances at 3, 6, and 9 months.The Journal of the Acoustical Society of America, 72, 353–365.
    • Kitamura, C., & Burnham, D. (1998). The infant’s response to maternal vocal affect.In C. Rovee-Collier (Ed.), Advances in infancy research (pp. 221–236). Norwood, NJ: Ablex.
    • Klatt, D. H. (1976). Linguistic uses of segmental duration in English: Acoustic and perceptual evidence.The Journal of the Acoustical Society of America, 59, 1208–1221.
    • Kuhl, P. K., Andruski, J. E., Chistovich, I. A., Chistovich, L. A., Kozhevnikova, E. V., Ryskina, V. L., & Lacerda, F. (1997, August1). Cross-language analysis of phonetic units in language addressed to infants.Science, 277, 684–686.
    • Kuhl, P. K., & Meltzoff, A. N. (1982, December10). The bimodal perception of speech in infancy.Science, 218, 1138–1141.
    • Lindblom, B. (1990). Explaining phonetic variation: A sketch of the H&H theory.In W. Hardcastle, & A. Marchal (Eds.), Speech production and speech modeling (pp. 403–409). Dordrecht, The Netherlands: Kluwer Academic.
    • Lindblom, B. E. F., & Sundberg, J. E. F. (1971). Acoustical consequences of lip, tongue, jaw, and larynx movement.The Journal of the Acoustical Society of America, 50, 1166–1179.
    • Liu, H. M., Kuhl, P. K., & Tsao, F. M. (2003). An association between mothers' speech clarity and infants' discrimination skills.Developmental Science, 6, F1–F10.
    • Locke, J. L. (1993). The child’s path to spoken language. Cambridge, MA: Harvard University Press.
    • MacLeod, A., & Summerfield, A. (1987). Quantifying the contribution of vision to speech perception by noise.British Journal of Audiology, 21, 131–141.
    • McRoberts, G. W., & Best, C. T. (1997). Accommodation in mean f0 during mother–infant and father–infant vocal interactions: A longitudinal case study.Journal of Child Language, 24, 719–736.
    • Mefferd, A. S., & Green, J. R. (2010). Articulatory-to-acoustic relations in response to speaking rate and loudness manipulations.Journal of Speech, Language, and Hearing Research, 53, 1206–1219.
    • Milenkovic, P. (2004). TF32 [Computer software].University of Wisconsin—Madison, Department of Electrical and Computer Engineering.
    • Montgomery, A. A., & Jackson, P. L. (1983). Physical characteristics of the lips underlying vowel lipreading performance.The Journal of Acoustical Society of America, 73, 2134–2144.
    • Moon, S.-J., & Lindblom, B. (1994). Interaction between duration, context, and speaking style in English stressed vowels.The Journal of Acoustical Society of America, 96, 40–55.
    • Munhall, K., Jones, J., Callan, D., Kuratate, T., & Vatikiotis-Bateson, E. (2004). Visual prosody and speech intelligibility: Head movement improves auditory speech perception.Psychological Science, 15, 133–137.
    • Murray, L., & Trevarthen, C. (1985). Emotional regulations of interactions between two-month-olds and their mothers.In T. M. Field, & N. A. Fox (Eds.), Social perception in infants (pp. 177–197). Norwood, NJ: Ablex.
    • Newborg, J. (2005). Battelle Developmental Inventory (2nd ed.). Itasca, IL: Riverside.
    • Patterson, R. L., & Werker, J. F. (2003). Two-month-old infants match phonetic information in lips and voice.Developmental Science, 6, 191–196.
    • Payton, K., Uchanski, R., & Braida, L. (1994). Intelligibility of conversational and clear speech in noise and reverberation for listeners with normal and impaired hearing.The Journal of the Acoustical Society of America, 95, 1581–1592.
    • Perkell, J. S., Matthies, M. L., Svirsky, M. A., & Jordan, M. I. (1993). Trading relations between tongue-body raising and lip rounding in production of the vowel /u/: A pilot “motor equivalence” study.The Journal of the Acoustical Society of America, 93, 2948–2961.
    • Picheny, M. A., Durlach, N. I., & Braida, L. D. (1985). Speaking clearly for the hard of hearing: I. Intelligibility differences between clear and conversational speech.Journal of Speech and Hearing Research, 28, 96–103.
    • Robb, M. P., Chen, Y., & Gilbert, H. R. (1997). Developmental aspects of formant frequency and bandwidth in infants and toddlers.Folia Phoniatrica et Logopaedica, 49, 88–95.
    • Rosenblum, L. D., Johnson, J. A., & Saldaña, H. M. (1996). Visual kinematic information for embellishing speech in noise.Journal of Speech and Hearing Research, 39, 1159–1170.
    • Rvachew, S., Slawinski, E. B., Williams, M., & Green, C. (1996). Formant frequencies of vowels produced by infants with and without early onset otitis media.Canadian Acoustics, 24, 19–28.
    • Schulman, R. (1989). Articulatory dynamics of loud and normal speech.The Journal of the Acoustical Society of America, 85, 295–312.
    • Slater, A., & Kirby, R. (1998). Innate and learned perceptual abilities in the newborn infant.Experimental Brain Research, 123, 90–94.
    • Smiljanic, R., & Bradlow, A. R. (2005). Production and perception of clear speech in Croatian and English.The Journal of the Acoustical Society of America, 118, 1677–1688.
    • Stern, D. N. (1985). Affect attunement.In J. D. Call, E. Galenson, & R. L. Tyson (Eds.), Frontiers of infant psychiatry, 2(pp. 3–14). New York, NY: Basic Books.
    • Stern, D. N., Spieker, S., Barnett, R. K., & MacKain, K. (1983). The prosody of maternal speech: Infant age and context related changes.Journal of Child Language, 10, 1–15.
    • Stevens, K. N. (2000). Acoustic phonetics. Cambridge, MA: MIT Press.
    • Stevens, K. N., & House, A. S. (1955). Development of a quantitative description of vowel articulation.The Journal of the Acoustical Society of America, 27, 401–493.
    • Sumby, W. H., & Pollack, I. (1954). Visual contribution to speech intelligibility in noise.The Journal of Acoustical Society of America, 26, 212–215.
    • Summerfield, Q. (1987). Some preliminaries to a comprehensive account of audio–visual speech perception.In R. Campbell, & B. Dodd (Eds.), Hearing by eye (pp. 3–51). Hillsdale, NJ: Erlbaum.
    • Summerfield, Q., MacLeod, A. M., McGrath, M., & Brooke, N. M. (1989). Lips, teeth, and the benefits of lipreading.In A. W. Young, & H. D. Ellis (Eds.), Handbook of research on face processing (pp. 223–233). Amsterdam, The Netherlands: North-Holland.
    • Summers, W. V. (1987). Effects of stress and final-consonant noticing on vowel production articulatory and acoustic analyses.The Journal of the Acoustical Society of America, 82, 847–863.
    • Swanson, L. A., Leonard, L. B., & Gandour, J. (1992). Vowel duration in mothers' speech to young children.Journal of Speech and Hearing Research, 35, 617–625.
    • Tasko, S. M., & McClean, M. D. (2004). Variations in articulatory movement with changes in speech task.Journal of Speech, Language, and Hearing Research, 47, 85–100.
    • Thiessen, E. D., Hill, E. A., & Saffran, J. R. (2005). Infant-directed speech facilitates word segmentation.Infancy, 7, 53–71.
    • Toda, S., & Fogel, A. (1993). Infant response to the still-face situation at 3 and 6 months.Developmental Psychology, 29, 532–538.
    • Trainor, L. J., Austin, C. M., & Desjardins, R. N. (2000). Is infant-directed speech prosody a result of the vocal expression of emotion?.Psychological Science, 11, 188–195.
    • Turner, G. S., Tjaden, K., & Weismer, G. (1995). The influence of speaking rate on vowel space and speech intelligibility for individuals with amyotrophic lateral sclerosis.Journal of Speech and Hearing Research, 38, 1001–1013.
    • Uther, M., Knoll, M. A., & Burnham, D. (2007). Do you speak E-NG-L-I-S-H? A comparison of foreigner- and infant-directed speech.Speech Communication, 17, 2–7.
    • van Wassenhove, V., Grant, K. W., & Poeppel, D. (2005). Visual speech speeds up the neural processing of auditory speech.Proceedings of the National Academy of Sciences USA, 102, 1181–1186.
    • Wohlert, A., & Hammen, V. (2000). Lip muscle activity related to speech rate and loudness.Journal of Speech, Language, and Hearing Research, 43, 1229–1239.

    Additional Resources