A cross-linguistic study of prosodic lengthening in child-directed speech

It has been widely documented that child-directed speech (CDS) may differ notably from adult-directed speech in terms of prosody (e.g. [1] [2] [3] [4]). Common features include higher and greater range of pitch, especially in stressed syllables; longer duration of individual words, more prominent final lengthening, slower speech rate, higher amplitude, shorter utterances and longer pauses, more even rhythm, and more reliable positioning of pauses at phrase boundaries ([2] [5] [6] [7]). From a functional point of view, one thesis is that the richness of prosodic cues in CDS may function to attract and maintain the attention of the child (e.g. [2] [5]) and communicate affective information [8]. Furthermore, it has been argued that CDS may actively facilitate language acquisition by, for example, highlighting linguistic structure and aiding word identification [9] [10] [11] [12]. However, evidence also suggests that certain kinds of prosodic modification (e.g. rhythmic) may be the result of an accommodation towards the child ([6] [7]). More generally, research has shown that young children and infants prefer listening to CDS to listening to ADS ([9] [13] [8]). Cross-linguistic studies have shown certain features to be particularly prevalent: for example higher pitch and wider pitch range [14] [2] [4] [15] [16]. However, the extent of exaggeration varies and exceptions exist: [4] report less exaggerated pitch characteristics in CDS in Mandarin Chinese (a tone language) than in American English. Most studies, be they monolingual or crosslinguistic, investigate the degree to which certain phonetic parameters of prosody are amplified in CDS. A little studied question is the extent to which certain aspects of prosody may be prioritized or even suppressed. In other words, does CDS merely exaggerate the marking of prosodic structure in ADS, or is it more selective? As an initial foray into this issue, this paper examines the phenomenon of prosodic lengthening in English and Catalan. It asks the following research questions: i) is there evidence of greater prosodic lengthening in CDS?; ii) if so, are certain prosodic structures highlighted more than others; iii) and if so, are there cross-linguistic similarities in this, or is the selection more language-specific? 2. Methodology