همبسته‌های آکوستیکی تکیه و تمایز دستوری افعال همسان گویش مشهدی

The present study deals with the homonymous verbs of the Mashhadi dialect that are used in different grammatical structures. These verbs were divided into two parts: two-syllable and more than two-syllable. Method: The present descriptive-analytical study was conducted on 10 male Mashhadi speakers in the age range of 40 to 60 years. The role of acoustic correlates of emphasis and its effect on the grammatical differentiation of homonymous verbs of the Mashhadi dialect was investigated using important acoustic parameters of speech tone, namely fundamental frequency, intensity, and duration. In this study, 960 verbs were produced and analyzed using Pratt speech analysis software. These verbs are in 8 grammatical tenses: present continuous and future, simple past and past perfect, past continuous and past perfect continuous, past perfect and past perfect. Dissyllabic verbs of distant tense are produced with more duration and lower pitch, while verbs of nearer tense have less duration and lower pitch. Polysyllabic verbs of distant tense have variable stress positions. This position was divided into two categories based on distance and proximity. Mashhadi speakers require two factors to induce the concept of distant time in two-syllable verbs: duration and base frequency, and in verbs with more than two syllables, it requires shifting the stress position. The increase in base frequency and duration was observed only in two-syllable distant time verbs. In verbs with more than two syllables, the increase in acoustic stress correlations did not occur due to the change in stress position.
 
Extended abstract
1.Introduction
Stress is a characteristic of the syllabic order, and a differentiator in some cases.  In the present study, the role of the distinctiveness of Stress in the grammatical differentiation of verbs in the Mashhadi dialect was examined. In the Mashhadi dialect, it was observed that some verbs are completely similar to each other and non-phonological factors have caused the distinction between them. It was observed that identical two-syllable verbs are identical even in terms of the position of the Stress, but Mashhadi speakers use factors other than Stress to differentiate these verbs. In identical verbs with more than two syllables, Stress was observed to be a differentiator between verbs. Because of this, in the present study, an attempt was made to use acoustic phonetics in order to examine more precisely the syllabic order factors effective in the grammatical differentiation of these verbs.
2.Theoretical framework
Regarding the acoustic correlates of the stressed syllable Frye (1955) stated that duration, sub-basement, vowel quality and loudness are the most important acoustic correlates of lexical stress. Also (F0) is the strongest production-sound sign of lexical stress and other factors such as duration, intensity and vowel quality have lesser effect on the phonetic realization of stress (Frye, 1955). Beckman and Edwards (1994) believe that what basically causes the contrast of lexical stress at the word level is sub-basement stress and the effect of other factors such as syllable duration and energy intensity is largely dependent on the vowel and the speaker. In order to observe the difference between completely identical verbs and verbs that are distinguished by a change in stress position, three acoustic correlates of stress were examined in the present study.
3.Methodology
In this study, eight grammatical tenses were examined, and for each grammatical tense, 3 two-syllable verbs and 3 verbs with more than two syllables were examined, and ten male speakers (aged 40 to 60 years) repeated these verbs twice. A (oral) questionnaire containing 48 questions was prepared, and the speakers' answers to the questions were the verb in question in the appropriate grammatical tense. A computer, microphone, and Pert software (version 5132) were used to record and measure the research data. The data were recorded and stored directly on the Pert software. Interrogative sentences were read to the speakers at appropriate intervals, and they repeated the appropriate answer twice. In total, 96 verbs (48x2) were obtained from each speaker and 960 verbs were obtained from the total number of speakers. In order to collect linguistic data and ask the speakers, the 8 categories of verbs under study were asked in the form of Interrogative sentences.
4.Results and Discussion
In the study of identical verbs, first the acoustic correlates of two-syllable verbs and then the acoustic correlates of verbs with more than two syllables were measured. Finally, the stressed syllable of both verb groups in identical grammatical tenses were compared with each other. This study was conducted to determine which acoustic correlates of stress have a higher frequency in which grammatical tenses and which correlates are more effective in inducing the desired tense concept. In the comparison of the two-syllable verbs in question, the identical stressed syllables were examined and the average of the stressed syllables was presented in the graphs. In verbs with more than two syllables, it was observed that the stress position changes for grammatical differentiation and these identical verbs do not have a higher level of acoustic correlations in the stressed position. In other words, the duration and base frequency in the stressed syllable of these two identical pairs do not differ much.
5.Conclusion & Suggestions
This study answered two main questions:
1- Are acoustic correlates used in the grammatical differentiation of identical verbs in the Mashhadi dialect? Yes, in completely identical two-syllable verbs, these acoustic correlates cause semantic and grammatical differentiation. In examining these verbs, it was observed that the further the grammatical tense of identical two-syllable verbs is from the speaker's speech tense or the speaker considers a more distant time when comparing two verbs, the more distant time is expressed with more tension and inflection than the closer time. Because of this, two-syllable verbs were divided into two categories: closer tense and more distant tense. In the comparison, present continuous verbs, simple past, past continuous and past perfect verbs were placed in the closer group, and future verbs, past perfect, past perfect continuous and past perfect continuous were placed in the more distant group. Finally, it was observed that verbs of nearer tense have lower duration and pitch than verbs of more distant tense. In other words, the Mashhadi speaker needs the duration and sub-bass factors to induce the concept of more distant tense in two identical two-syllable verbs.
2- Do two-syllable and more than two-syllable verbs differ in the selection of acoustic correlates? Yes, completely identical two-syllable verbs in the Mashhadi dialect require the duration and sub-bass factors to induce the concept of more distant tense, but verbs of more than two syllables use the stress position to induce the concept of more distant and closer tense. In this structure, too, there is a more distant and closer temporal concept for completely identical verbs, but the change in the stress position of verbs of more than two syllables from the second syllable to the third syllable is the cause of semantic and grammatical differences. Verbs that have a more distant temporal relationship with the speaker have their third syllable stressed, and verbs that are closer to the speaker's time have their second syllable stressed. To convey the concept of more distant time in completely identical verbs of three syllables and more, Mashhadi speakers need to change the stress position. Another result of this study is that Mashhadi speakers have a high auditory sensitivity to stress contrasts; that is, listeners of the Mashhadi dialect are highly sensitive to acoustic changes caused by the shift in the location of the phonetic prominence, and acoustic changes have caused syntactic changes in this dialect.
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