The purpose of the present study was to tease apart the paralinguistic from the linguistic aspects of infants' perception of infant-directed (ID) speech. Several studies have shown that infants beginning at a few days after birth discriminate native from nonnative speech and can discriminate specific contours (rising, falling, rising-falling) in ID speech. Some studies have also indicated that infants at 4.5 months of age prefer their own name over other names but at 6 months of age, fail to prefer a sentence with their own name embedded in it. Using a discrimination procedure, the current study investigated whether 6-month-old infants could detect a change in contour and/or a change in words when listening to ID utterances. Results indicated that 6-month-old infants detected both a contour and a word change. From these results, it is argued that as has been shown in other experiments, infants are extremely sensitive to subtle changes in speech. Furthermore, ID speech appears to facilitate infants' ability to discriminate small changes in ID speech (both linguistic and paralinguistic). It is suggested that future studies investigate more discrete changes in speech samples and a replication of this research with adult-directed (AD) speech. / Master of Science

Phonetic aspects of mother-infant interaction are discussed in light of a functionalist Mother-infant phonetic interaction (MIPhI) model. Adults addressing infants typically use a speech style (infant-directed speech, IDS) characterized by, for instance, extensive suprasegmental (prosodic) modulations. This type of speech seems to interest young infants whose active experience with the spoken language appears to focus their speech perception on the phonological properties of the ambient language during the first year of life. This thesis consists of four articles discussing phonetic modifications at the suprasegmental, segmental and phonological levels, based on data from six Swedish mothersí IDS to their 3-month-olds. The first study concerns the tonal word accent 2 in disyllabic words, and shows how the lexical, bimodal, tonal characteristics of this accent are enhanced in IDS as compared to adult-directed speech (ADS). The second is a cross-linguistic investigation of vowel formant frequencies in Swedish, Am. English and Russian IDS. It shows that vowels like /i/, /u/, and /a/ are more clearly separated in IDS than in ADS, in all three languages. The third study addresses the voiced /voiceless contrast in stop consonants as measured by voice onset time (VOT) and shows that stop consonants seem to be poorly separated in early IDS samples. The fourth study investigates the quantity distinction in V:C and VC: sequences and indicates that this phonological contrast is well maintained in the IDS. Adult data are discussed within the MIPhI model, assuming that suprasegmental and segmental specifications in IDS follow different phonetic specification paths adapted to the infantsí capacities as these develop over the first 18 months of life. The adultsí phonetic adaptations appear to reflect a selective strategy of presenting linguistic structure in a ìgift-wrappingî that is attractive and functional for the infant. / För att köpa boken skicka en beställning till exp@ling.su.se/ To order the book send an e-mail to exp@ling.su.se

Infants of various ages across the first postnatal year have shown behavioral preferences (i.e., more attention) to visual displays when looking resulted in the presentation of Infant-Directed Speech (IDS) compared to Adult-Directed Speech (ADS). Although IDS differs from ADS on a variety of measures, most research has focused on various pitch characteristics (i.e., IDS is higher in absolute pitch and more variable in pitch across utterance length). Work from our lab has found that when the pitch characteristics of IDS were held constant, but the temporal features were manipulated, younger (but not older) infants attended more to slower rates of IDS, even though it was unlikely that they had heard such speech (when speech is spoken at this slow rate, the fundamental frequency cannot be maintained). The purpose of this study was to expand our investigation of how speaking rate affects infant attention by adding the physiological measure of heart rate to our protocol. Of specific interest was whether infants would show differential amounts of heart-rate (HR) decelerations as a function of rate (i.e. greater decelerations to slowed speech). 4-month-old infants were tested with normal IDS (unaltered rate) and slow IDS (rate was twice as slow as normal). Behaviorally, infants did not differentially attend to a display as a function of speech type. Psychophysiologically, infants showed more pronounced HR decelerations to slow than to normal IDS. The discrepancy between measures of attention is discussed, especially with regard to the organization of attention in infants of this age. / Master of Science

Much research has examined how rate affects visual preferences in human infants and auditory preferences in avian infants. In the visual domain, it seems that human infants prefer stimuli (e.g., flashing displays) presented at faster relative rates. Research using avian species has shown that ducklings, for example, prefer their species- specific maternal call only when it is presented at values close to the species-typical mean. These studies have shown that experience affects ducklings'­ preferences for rate in auditory events. Researchers in the areas of human infant preferences for visual rate and avian infant preferences for auditory rate have suggested that an effective window of frequencies exists for which infants show maximal attention. Unlike these two areas, little research has addressed how rate affects human infants' preferences for auditory events. A study by Cooper and Cooper (1997) was the first to find that infants attend to rates of speaking infant directed (ID) speech. Specifically, infants preferred ID speech at its normal rate to ID speech at a faster rate. The present study was intended to further investigate how rate of speaking affected infants' preferences for ID speech. More specifically, this study sought to determine whether a window of effective rates also exists for infant preferences for rate in ID speech. Using an infant-controlled preference procedure, 20 six- to eight-week old infants were presented with ID-normal speech (ID speech as its normal rate) and ID- slow speech (ID speech slowed to half the normal rate). It was found that infants looked longer to a visual display when it was paired with ID-slow speech than when it was paired with ID-normal speech. How these results relate to research and theory on visual rate preferences in human infants and auditory rate in avian species is discussed, as well as future directions for this line of research. / Master of Science

Infant speech perception develops within the context of specific language experience. While there is a corpus of empirical evidence concerning infants' perception of linguistic and prosodic information in speech, few studies have explored the interaction of the two. The present investigation was designed to combine what is known about infants' perception of nonnative phonemes (linguistic information) with what is known about infant preferences for ID speech (prosodic information). In particular, the purpose of this series of studies was to examine infant preferences for ID speech within the timeline of the phonemic perceptual reorganization that occurs at the end of the first postnatal year. In Experiment 1, 20 Native-English 10- to 11-month-old infants were tested in an infant-controlled preference procedure for attention to ID speech in their native language versus ID speech in a foreign language. The results showed that infants significantly preferred the ID-native speech. In Experiment 2, the preferred prosodic information (ID speech) was separated from the preferred linguistic information (native speech), as a means of discerning the relative perceptual draw of these types of speech characteristics. Specifically, a second group of 20 10- to 11-month-old infants was tested for a preference between ID speech in a foreign language and AD speech in their native language. In this case the infants exhibited a significant preference for ID-foreign speech, suggesting that prosodic information in speech has more perceptual weight than linguistic information. This pattern of results suggests that infants attend to linguistic-level information by 10- to 11-months of age, and that ID speech may play a role in the native-language tuning process by directing infants' attention to linguistic specifics in speech. / Master of Science

The purpose of the present study was to investigate the role of pitch contours in directing infant attention to adult speech. Several studies have shown that infants from a few days old to 9 months of age prefer infant-directed (ID) over adult-directed (AD) speech. Moreover, 4-month-olds have been shown to prefer pitch contours that simulate ID speech, suggesting that the exaggerated pitch contours are necessary for infant attention. The current study investigated this attentional preference utilizing ID and AD pitch contours in a fixation-based preference procedure. Results from the first experiment failed to show a similar preference for the ID pitch contours. Because a lack of preference could have been due to a failure to discriminate, a habituation study was also conducted. The results from the second experiment showed that 4-month-olds can discriminate the ID and AD pitch contours. From these results, it is argued that the pitch contour may be but one of many possible prosodic characteristics that attract infant attention and this attention may occur only within a language context. It is suggested that future studies investigate ID speech using a more context-dependent procedure, where natural or more complete speech samples are utilized. / Master of Science

A recent study by Polka, Rvachew, and Molnar (2008) found that 6- to 8-month-old infants do not discriminate a simple native consonant-vowel contrast when familiarized to it in the presence of distraction noise (i.e., recordings of crickets and birds chirping), even when testing was conducted in quiet. Because the distraction noise did not overlap with the phonemes' frequencies, failure to encode the familiarization phoneme could be due more to a disruption in infant attention than to direct masking effects. Given that infants learn speech under natural conditions involving noise and distraction, it is important to identify factors that may 'protect' their speech perception under non-ideal listening conditions. The current study investigated three possible factors: speech register, face information, and speaker gender. Six-month-old infants watched a video of a female speaker producing a native phoneme in either an adult-directed or infant-directed manner accompanied by the same background noise as in Polka et al. (2008). After habituation, infants were tested with alternating trials of the familiar phoneme and a novel phoneme in quiet. Phoneme discrimination was measured by recording infants' heart rate and looking times during familiar and novel trials. Discrimination was poor in infants who viewed a female speaker using adult-directed speech but was significantly improved (as seen in both dependent measures of attention) when the female speaker used infant-directed speech. Results indicate that common factors in the typical environment of infants can promote speech perception abilities in noise. / Master of Science

No description available.

Existing literature demonstrates that infants can discriminate between categories of infant-directed (ID) speech based on the speaker’s intended message – that is, infants recognize the difference between comforting and approving ID speech, and treat different utterances from within these two categories similarly. Furthermore, the literature also demonstrates that infants understand many aspects of music and can discriminate between happy and sad music. Building on these findings, the present study investigated whether exposure to happy or sad piano music would systematically affect infants’ preferences for comforting or approving ID speech. Five- to nine-month-old infants’ preferences for comforting or approving ID speech were examined as a function of whether infants were exposed to sad or happy piano music. Seventeen (10 male, 7 female) full-term, healthy infants were included in the study. It was hypothesized that relative to infants exposed to happy music, infants exposed to sad music would demonstrate a stronger desire to hear comforting ID speech. The study employed an infant controlled, preferential looking procedure to test this hypothesis. The results of the study did not statistically support the researchers’ hypotheses. Limitations of the present work and suggestions for future research are discussed.

The present study was designed to investigate whether infants prefer their fathers’ voices over an unfamiliar male voice within the context of normal father-infant interaction, i.e., infant-directed (ID) speech. Twenty Caucasian male and female four-month-olds were tested in a visual-fixation preference procedure. Attentional preference was measured by the amount of time the infants watched a visual stimulus. It was found that infants did not show greater attentional or affective responsiveness to paternal ID over unfamiliar male ID speech samples. However, mothers and fathers appear to be very similar in their perception of father-infant interaction. According to these results, four-month-olds do not prefer their fathers’ voices to that of an unfamiliar male. This finding contrast sharply with the literature on maternal voice preference. The data was interpreted as supporting the hypothesis that multimodal stimulus cues are necessary for paternal voice recognition in infancy. / Master of Science