Duration and intensity as perceptual cues for naïve listeners' prominence and boundary perception

I investigate the acoustic correlates of prosodic prominence and boundary, as they are perceived by naive listeners, in spontaneous speech from American English (Buckeye corpus). Prosodic prominence and phrasing serve different functions in speech communication: prosodic phrase boundaries demarcate speech chunks that typically cohere semantically, while prominences encode focus and possibly also rhythmic structure. The acoustic correlates of prominence and phrase boundary are examined through measures of vowel duration and overall intensity of stressed vowels, to see how those measures correlate, individually or in combination, with naive listeners’ perception of prominence and boundary. The results show that most stressed vowels are lengthened in preboundary words (i.e., those final in the prosodic phrase). Prosodic prominence is also cued by increased duration, but in combination with higher overall intensity for some vowels. These acoustic differences associated with perceived prominence and boundary suggest different mechanisms underlying their production. This claim finds support from consideration of the different functions that prominence and boundary play in encoding information structure, and in speech production planning.