چکیده:
Vahid Sadeghi [1] Date Received: 20/1/90 Date Approved: 18/10/90 Abstract: In most studies conducted on lexical stress in the Persian language, phonetic changes resulting from the displacement of the stress position in pitch-accent environments have been investigated; for this reason, F0 has been considered the most important phonetic correlate of lexical stress; whereas F0 is the phonetic correlate of pitch accent, not lexical stress; furthermore, in the studies conducted, the validity of other factors such as changes in energy intensity and duration has not been tested as potential correlates of lexical stress. In this article, we have investigated the phonetic correlates of lexical stress in the Persian language in two different prosodic contexts: one context with pitch accent and another without pitch accent; to this end, we conducted a production experiment in which we compared syllable duration, total energy intensity, energy intensity of frequencies above five hundred Hertz, and formant frequencies (as vowel quality correlates), stressed and unstressed vowels in Persian stress word pairs and their meaningless equivalents. The research results indicate that the change in formant frequencies as well as the change in the energy intensity of the frequency spectrum, both in all frequency regions and in middle and high frequency regions, is a function of pitch change and for this reason, these factors are considered phonetic-acoustic correlates for pitch accent, not lexical stress; conversely, syllable duration in both prosodic contexts distinguishes stressed syllables from unstressed syllables, and thus, this factor, independent of pitch change, is considered the most valid phonetic-acoustic indicator for lexical stress in Persian. Keywords: lexical stress, pitch accent, total energy intensity, phonetic-acoustic correlates, target stimulus. 1. Assistant Professor at Imam Khomeini International University Vsadeghi5603@gmail.com This research was supported by the research grant of Imam Khomeini International University with support number 92-386002.
خلاصه ماشینی:
The research results indicate that the change in the frequency of structures and also the change in the energy intensity of the frequency spectrum, both in all frequency ranges and in the mid and high frequency ranges, is a function of pitch change; for this reason, these factors are considered generative-phonological correlates for pitch accent, not lexical accent; on the other hand, syllable duration in both prosodic contexts distinguishes stressed syllables from unstressed syllables, and thus, this factor, independent of pitch change, is considered the most reliable generative-phonological indicator for Persian lexical accent.
A listener perceives a syllable as stressed if its F0 valley is higher compared to its adjacent syllable(s), or if the amount of base frequency change on it is greater compared to the adjacent syllable; in other words, the listener is sensitive to the location of prosodic prominence on the speech pitch contour for perceiving lexical accent, and wherever prominence exists, they hear it as a stressed type; therefore, from Fry's perspective (1958), F0 is the strongest perceptual indicator for lexical accent, and other factors such as duration, energy intensity, and vowel quality are less effective in the perception of accent; accordingly, he concluded that the role of lexical accent is to specify the potential locations of prosodic prominence on the speech pitch contour.
(1997) repeated the experiments of Sluyter and Van Horn by selecting their proposed variables on English word pairs in a context without pitch accent; however, their findings did not show a significant difference in terms of energy intensity levels in mid and high frequencies.
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