The development of clear speech strategies in 9-14 year olds

This study investigated the development of global clear speech strategies of child talkers. Two groups of 20 talkers aged 9-10 (children) and 13-14 (teens) were recorded in pairs while they carried out spot the difference picture tasks, either hearing each other normally (NB condition) or with one talker hearing the other via a three-channel noise vocoder (VOC condition). Acoustic-phonetic analyses focused on the talker having to overcome the communication barrier. Data were compared to those for 20 of the adults in Hazan and Baker (2011) [J.Acoust.Soc, Am, 130, 2139-2152]. The three age groups did not differ in task transaction time for NB, but children took significantly longer to complete the task in VOC than teens or adults who took equally long. Children spoke at a slower speech rate overall than teens, while teens and adults did not differ; all groups significantly reduced their speech rate in VOC relative to NB. Adults hyperarticulated vowels in VOC but children and teens showed only minor adaptations. These results suggest that although 9-10 year olds use some strategies to clarify their speech in difficult conditions, other strategies continue to develop into late adolescence