Phonetic Reflexes of Morphological Boundaries at a Normal Speech Rate

Our production experiment in Scottish English revealed that the duration of a rhyme immediately followed by a Level II suffix such as –s (the 1 person singular/plural/possessive suffix) and –t (the past tense suffix) was significantly longer than that of a monomorphemic counterpart. Such a durational difference between suffixed forms and monomorphemic forms was absent when the Level II suffix was –er (the agentive suffix) or –ing (the progressive suffix). Those results may indicate that morphological boundaries (i.e. stem-suffix boundaries) are not directly influencing acoustic duration adjustment and support a prosody-phonetics interface hypothesis that the phonetic component is only accessible to prosodic structure (but not to morpho-syntactic structure). We also found that the rhyme duration of suffixed forms was shorter than the duration of a comparable rhyme in two-word sequence forms. This result, however, does not necessarily refute a hypothesis that there is a lexical/prosodic word boundary at the stem-suffix boundary because the presence of the word boundary at the stem-suffix boundary still allows “polysegmental” shortening to be applied to a higher word that dominates both the stem and the suffix.