An Acoustic Study Of Chinese EFL Learners' Sentence Stress:From A Discourse-Prosodic Perspective

The research is based on the HPG Modal(Hierarchy of Prosodic Phrase Group),which presents the sentence stress assignment within the connected speech.By comparing native speakers with Chinese EFL learners,the speech data are analyzed to illustrate:(1)What are their differences in the emphasis distribution of perceived highlights and by prosodic boundary?(2)What are their differences in the distribution of break boundary?Besides,this paper applied TGA(Time Group Analysis)to analyze rhythm and duration pattern in order to illustrate:(3)What are their differences in the rhythm and duration patterns?Results show that:(1)Native speakers assign the emphasized E2 and extremely emphasized E3 on the content words.Reduced EO is assigned on the function words.Chinese EFL learners did not reduce vowels to a native-like degree and tended to use much higher pitch register.Stress is realized by Chinese EFL learners as pitch movement,with nonstandard realization of stress on nearly every word,including function words.Native speakers produce a large degree of contrast across sentence levels,while male Chinese EFL learners produced no apparent stress contrast.Instead,female EFL learners tend to use more emphasis.For the emphasis distribution by prosodic boundary,native speakers emphasized on the final of the PPh(Prosodic Phrase),while the EFL learners emphasized on the initial and medical of the PPh.(2)In regard to the distribution of break boundary,Chinese EFL learners use more prosodic phrase boundary B3 and fewer larger-scale planning units B4(breath group)and B5(prosodic group)in prosodic discourse organization than native speakers.(3)With respect to rhythm metrics,native speakers have higher rPVI-C and lower nPVI-V than EFL learners.Furthermore,male EFL learners' rPVI are lower than female EFL learners'.In terms of Temporal Dispersion,native speakers place more values in the shorter-shorter quadrants than Chinese EFL learners.In addition,native speakers tend to cluster more values in shorter-longer and longer-shorter quadrants which shows the alternative variation between stressed and unstressed sounds.Instead,Chinese EFL learners tend to cluster more values in the longer-longer and longer-shorter quadrants.In terms of duration patterns,native speakers present a variety of contrast stress.Chinese EFL learners intend to utter every sound in a similar tempo and duration,which indicates a syllable timed rhythmic pattern.The results reveal that Chinese EFL learners' speech is produced with inappropriate sentence stress assignment.Moreover,less robust realization of necessary stress contrasts is consistent with the use of more intermediate chunking units and fewer larger-scale planning units in their prosodic discourse organization.The rhythm reveals the syllable timed features that are distinct from native speakers'.The differences of the sentence stress distribution and rhythm patterns can be attributed to prosodic transfer of Mandarin and lead to the interlanguage phenomena for Chinese EFL learners.