جستجوی مقالات مرتبط با کلیدواژه « تکیه زیروبمی » در نشریات گروه « ادبیات و زبان ها »

This research aims to improve speech synthesis in Persian and investigate the pitch contour fall between two H* peaks carried out in the framework of the Autosegmental Metrical (AM) theory of intonational phonology. In this paper, we tested two main hypotheses. Firstly, the F0 falls through phonetic interpolation and, secondly, it involves tone spreading. The present paper argues that the first hypothesis is proven to be correct. The data for the present research includes 45 enclitic phrases that were produced using voiced consonants between the two peaks. It means that in the course of producing each phrase, it was taken into consideration that all of the consonants placed between the two peaks would be deliberately and certainly voiced. This is mainly because if the consonants were not voiced, the data analysis results would be affected in Praat. It has to be noted that the distance between the two H* was increased by adding zero to two unstressed syllables. Totally, we recorded 1350 utterances from 30 native Persian speakers. We employed Praat software so as to analyse the utterances. Besides, we utilized SPSS for further analysis. The results of acoustic and statistical analyses showed that the distance between the first peak and the following F0 valley is increased with the addition of the unstressed syllables, demonstrating the alignment of this valley with the beginning of the stressed syllable. Results of statistical analyses revealed that the distance between the H and the following L target is increased significantly with the addition of the unstressed syllables. Furthermore, the normalized pitch contour was computed for all data. This indicates that the fall of the pitch contour between the two H peaks is realized through phonetic interpolation.

In languages and varieties, the exact locations of the alignment of f0 transition points differ from those of the segmental string (Ladd, 2006). The differences of inter-languages or inter-varieties are sometimes so small that it is not possible to identify a deep representation. We conducted a production experiment with 40 speakers of two regional varieties of Persian language. The aim of the present study was to investigate the strategies used by the speakers of the varieties in response to the time pressure caused by reduced sonorant rime of target words by adopting autosegmental-metrical theory (Pierrehumbert, 1980). For this purpose, 20 Isfahan speakers and 20 Tehrani speakers were asked to repeat the three target words, which were accompanied by a decrease sonorant rime, in the positions of nuclear pitch accent twice. Three prosodic parameters, such as contour conditionm alignment, and duration of the segments containing pitch accents, were mainly considered. The results showed that in each contour condition, the duration of the sonorant rime of the nuclear accented word was varied. In the phonetic domain, the range of adjustments fell into three broad categories. First, the speakers of Isfahani variety took more time by increasing the duration of the rime in the fall-rise condition while retracting the peak of the fall-rise contour. However, the speakers of Tehrani variety worked harder by compressing contours in the fall contour. Both speakers of the two varieties took shortcuts by truncating responses of the final pitch movements. The responses were shown to be dialect-specific and contour-specific.

There are two competing views with respect to the tonal structure of Persian pitch accents. According to the first view, peak delay in Persian intonational grammar serves no phonological or contrastive function. This view assumes that the earlier or later peak alignment in Persian does not lead to contrasts in intonational meanings. As such, pitch accents in Persian are phonologically characterized as either L+H* or L*+H. According to the second view, it is assumed that both L+H* and L*+H exist in Persian intonational phonology, but they act at different layers of Persian prosodic structure: L+H* operates at the level of phonological word, while L*+H functions at the level of enclitic group. The present study addressed the phonetic behavior of Persian pitch accents in different prosodic contexts. The phonetic evidence found in this research shows that the tonal structure of Persian includes only one pitch accent, namely L*+H, whose peak (H tone) is realized with magnitude degrees of late alignment from no delay to long delay according to peak alignment continuum.

The present research is a corpus- based study on Persian intonation. Previous studies on Persian intonation have only focused on experimental data and to date few researches have been carried out on Persian intonational patterns as realized in natural spoken corpora. The aim of the present research is to evaluate the intonation patterns of Persian content and grammatical words in a natural spoken corpus. The content words included nouns, verbs, adjectives and adverbs, and the grammatical words included pronouns, prepositions and copular verbs. Earlier researches posit two types of pitch accent in Persian intonatioanl grammar: A bitonal pitch accent, namely L+H* that marks words with stress on a non-initial syllable, together with their enclitics, and a mono-tonal pitch accent, i.e., H* that describes mono-syllabic words or initial-stressed words. The question addressed in the present contribution is to what extent the intonational patterns assumed in the Persian intonation literature may be replicated in studies of Persian natural spoken corpora.    This research is based on the Auto-segmental theory of intonation. The intonational structure under this theory is composed of a number of tonal events aligned with specific segmental landmarks. The most important tonal events are pitch accents and boundary tones. Pitch accents are associated with stressed syllables while boundary tones are aligned with the boundary of prosodic units. These tonal events are called tonal targets as they are linked with specific segmental landmarks in the speech signal. The auto-segmental theory of intonation posits six pitch accents namely H*، L*،L+H*، L*+H، H+L*، H*+L.Among these pitch accents, L* and H* are mono-tonal, while L+H*، L*+H، H+L*، H*+L are bitonal. A mono-tonal accent is one which is composed of either a single high (H*) or low (L*) tone. Bitonal accents, on the other hand, are compound tones made of a combination of a low and a high tone, irrespective of their order.   The Methodology of the research is descriptive. A number of Persian content words, including nouns, verbs, adjectives and adverbs, and grammatical words including pronouns, prepositions and copular verbs, were randomly selected from 104 utterances from FarsDat (Farsi spoken language database). All the utterances had been spoken by native speakers of Persian speaking the standard dialect of Tehrani Farsi. The target words, content and grammatical, were segmented from the acoustic signals of the utterances for further analysis. All acoustic parameters were measured using Praat software, version 5.2.12.
Measurements were made simultaneously on F0 contour and spectrograph. The F0 patterns of the target words were investigated to see whether they bear a pitch accent, and if they do, what kind of pitch accent they are most associated with.  The results suggested that while content words usually receive pitch accents, grammatical words are rarely produced with a pitch accent. The findings further suggested that the morpho-syntactic category of a given word is unable to affect its tonal pattern. The distribution of the pitch accent types H* and L*+H revealed that Persian words are most often produced with the L*+H accent type, irrespective of their lexical stress pattern, and that the H* is used in initial-stressed words only when the segmental condition for the realization of the L tone is not satisfied. It was also argued that the alignment of the H tone in L*+H accent is affected by the presence or absence of enclitics in a word: In words with an affixed enclitic, the H peak is delayed, and realized in the post-accented syllable, while in words with no enclitic pronoun, the peak is realized on the accented syllable with no delay. Overall, the findings of the present research indicated that all Persian words, irrespective of their stress pattern receive the bitonal pitch accent L*+H, and the pitch accent H*is realized on words with initial stress only when the phonological condition for the realization of the L tone is not met.

Introduction Linguistic stress and pitch accent are two prosodic cues to word-level prominence. Lexical stress is a prosodic event that helps disambiguate minimal stress pairs (Silber-Varod, Sagi, and Amir, 2015). It happens in polysyllabic words to lend prominence to a syllable as compared to other syllables in the same word. Thus, lexical stress implies the prominence of one syllable in relation to other syllables within a word. But, prominence is not restricted to the word level. It may also occur at the sentence level. This second kind of prominence is called pitch accent. Accent is an intonational event according to which some words in a sentence are produced with more prominence for pragmatic purposes (Sluijter and van Heuven, 1996). Thus lexical stress belongs to linguistic competence, while accent belongs to linguistic performance (Eslami, 2010; Sadeghi, 2014).
According to the typological classification of Hyman (2014), languages are of two prosodic types: stress-accent and non-stress-accent languages. Stress-accent languages are those in which stress is phonetically realized in a word to make one syllable more prominent than other syllables. In contrast, non-stress-accent languages are those in which syllables are free of any phonetic prominence at the word level, and prominence in these languages is the result of pitch accent at the sentence level.
In addition to lexical stress and pitch accent, the prosodic position of a syllable may also affect its prominence in a word. The present paper addresses the role (or contribution) of stress, accent and syllable position on word level prominence in Persian. Prominence is operationalized in this research through three acoustic parameters, namely F0, duration and overall intensity.
Theoretical framework The present research is carried out within the framework of Laboratory Phonology. Any research within this theoretical framework starts with a phonological hypothesis. This hypothesis is assumed to represent a phonological model of the phonetic pattern in question. Then, a production or perceptual experiment is conducted to evaluate the hypothesis. For this purpose, a sample of data related to the phonological hypothesis is designed and calculated. Some acoustical correlates are selected and measured under experimental control of all factors that are assumed to affect the result of the experiment. The values of the parameters calculated are statistically processed, and the results obtained are used to assess the validity of the hypothesis formulated.
Methodology A corpus of 144 sentences was used to evaluate the hypothesis in question. The target words used in the sentences included all the six vowels of the Persian language. There were two types of words in the data: two-syllable words with cv.cv syllable structure and three-syllable words with cv.cv.cvc syllable structure. Stressed and unstressed syllables were embedded in the two-syllable words in final and initial positions respectively, while syllables in the medial position of the three-syllable words were undefined for prominence. All the three-syllable words were formed by adding a stress-bearing mono-syllable affix (inflectional or derivational) to the two-syllable words. All the target words were embedded in two intonational contexts to yield accented and unaccented productions. All acoustic parameters were measured using Praat, version 5.2.12. Measurements were made simultaneously on F0 contour, intensity contour and spectrograph.
Results & Discussion The results for F0 showed no syllables except for the final syllable receive a prominence-lending pitch movement. The results for overall intensity indicated that like F0, intensity correlates with accent rather than stress or syllable position. The results for duration suggested that the initial unstressed syllables are longer than final stressed syllables, and that final stressed syllables are longer than medial unstressed syllables. Furthermore, differences in duration between the syllables concerned were found to be significant even in the unaccented condition. These results were interpreted as suggesting that there are two prosodic factors affecting word-level prominence in the paradigmatic axis, namely stress and syllable position, where syllable position outweighs stress in lending more prominence to initial syllables in poly-syllabic words.
Conclusions & Suggestions Overall, the results suggested that unlike F0 and intensity, duration in Persian is an acoustic correlate of both stress and syllable position which interacts with each other to determine the prominence of syllables in Persian poly-syllabic words.

This article addresses the phonetic and phonological representation of H- phrase accent in the tonal structure of Persian pre-nuclear accents. In an experimental study, three groups of pre-nuclear accentual phrases, namely, phrases with antepenultimate, penultimate and final stress pattern, were selected for tonal examination. Materials were designed so as to yield under-pressure and pressure free prosodic environments. The sentences were then read by four speakers of standard Persian. Results revealed some evidence for the presence of phrase accent as a part of the tonal structure of all groups, except for oxytones in which there is not sufficient segmental space for the realization of the H- phrase tone. Thus, we may transcribe pre-nuclear accents in Persia as a sequence of an L+H* pitch accent and a H- phrase accent: L+H*H, whereby L+H* is associated with the stressed syllable and the H- is spread as a plateau from the accented syllable to the end of the accentual phrase. The observations further revealed that the H- plateau is realized in different ways depending on the stress pattern of the accentual phrase. The H- plateau can best be explained using the tone copy analysis which assumes that a plateau results from copying a phrase accent from the boundary to units which do not bear tones such as final syllables.

Tonal features and pitch accent model of clitic groups and phonological words show that these are two different phenomena. The difference is that the pitch accent model of H* is located on the last syllable in phonological word and on the syllable before clitic in clitic group. Therefore, clitic is independent of phonological word from tonal viewpoint. Also there is no sign of H-rising edge tone after the non-final AP; rather, the edge tone is L-and the rising of F0 on clitic is called Peak delay

This article studies the perceptual correlates of lexical stress in Persian. The minimal stress pair was used as the stimulus token, and the values of duration, overall intensity, spectral balance and F0 were varied in several steps both in the accented and de-accented conditions. 20 native Persian speakers were asked to identify the stressed tokens in a force-choice perception experiment. The results showed that in the accented condition, F0 is the most reliable perceptual correlate of stress. Other correlates are in additive interaction with F0. In de-accented condition, stress is strongly cued by duration, while among the other correlates, spectral balance provides stronger stress cues than overall intensity.