Res. Lab. of Electron., MIT, 77 Massachusetts Ave., Cambridge, MA 02139
Some words of English can bear their major prominence on a strong syllable earlier than the main-stress syllable; this ``stress shift'' phenomenon has recently been discussed in terms of early placement of phrase-level prominences, or pitch accents. Factors that might cause speakers to place a pitch accent early in a target word include (1) structural position (accent the first accentable syllable in a new prosodic phrase), (2) rhythmic regularity (avoid placing accents too close together or in irregular patterns), and (3) one or more earlier appearances of the same word within the discourse. In a preliminary experiment designed to establish whether these factors influence pitch accent placement, two FM radio announcers read stories constructed with a ``shiftable'' target word or phrase (e.g., caffein, international, Cape Cod) in four different positions. Prominence locations were transcribed by listeners who were naive with respect to the predictions. Results showed more frequent placement of prominence on the main-stress syllable of target words and phrases when they occurred in phrase-final position (first and second mention), but on their earlier strong syllable when they occurred in initial position or in clash context (third and fourth mention). Preliminary acoustic analyses suggest that the labeled prominences correspond to substantial F0 markers, strengthening the hypothesis that at least some instances of perceived stress shift are cued by pitch accent patterns.