Relationship of prosody by Spanish speakers of English as a second language on the perception of intelligibility and accentedness by native English listeners

The degree to which prosodic features related to English lexical stress affect the perception of factors such as intelligibility and accentedness by native English listeners was investigated. Acoustic analyses of English multi-syllabic words spoken by native Spanish speakers who learned English as a second language (ESL) were used to determine the values of the acoustic correlates of lexical stress of these speakers on a set of target words. Values for vowel duration, intensity, and fundamental frequency produced by the Spanish ESL speakers were compared to those values produced by native English speakers. Prosodic variation observed in the ESL speakers was used to formulate a range for manipulations to the target words. To focus solely on prosody and not take into account consonant and vowel quality, manipulations, using the PSOLA algorithm in Praat, were done to the voices of native English speakers. These manipulations captured increases and decreases in duration, intensity, and fundamental frequency on vowels that should or should not carry lexical stress in a particular target word. Listeners rated the resynthesized tokens for factors such as intelligibility and accentedness, and the results suggest that a speaker’s prosody alone can influence a native listener’s judgments on these variables.