Vowel In Sequence Research Articles

Characterizing resonant component in speech: A different view of tracking fundamental frequency

Inspired by the nonlinearity and nonstationarity and the modulations in speech, Hilbert–Huang Transform and cyclostationarity analysis are employed to investigate the speech resonance in vowel in sequence. Cyclostationarity analysis is not directly manipulated on the target vowel, but on its intrinsic mode functions one by one. Thanks to the equivalence between the fundamental frequency in speech and the cyclic frequency in cyclostationarity analysis, the modulation intensity distributions of the intrinsic mode functions provide much information for the estimation of the fundamental frequency. To highlight the relationship between frequency and time, the pseudo-Hilbert spectrum is proposed to replace the Hilbert spectrum here. After contrasting the pseudo-Hilbert spectra of and the modulation intensity distributions of the intrinsic mode functions, it finds that there is usually one intrinsic mode function which works as the fundamental component of the vowel. Furthermore, the fundamental frequency of the vowel can be determined by tracing the pseudo-Hilbert spectrum of its fundamental component along the time axis. The later method is more robust to estimate the fundamental frequency, when meeting nonlinear components. Two vowels [a] and [i], picked up from a speech database FAU Aibo Emotion Corpus, are applied to validate the above findings.

Glottal Stop in Hiatus: An Acoustic Investigation in Persian

One of the strategies to resolve hiatus in Persian is glottal stop (GS) insertion between two adjacent vowels (Sadeghi, 2001: 27, 28) [1]. This paper investigates the presence of GS in hiatus within and across morpheme boundaries in isolated words (684 tokens) as well as in words within sentences (276 tokens). Four speakers of standard Persian (two females and two males) between the ages of 31 and 37 participated in this study. Acoustic analysis of the data by Praat [2] showed three acoustic correlates of GS in intervocalic environments; in addition to a complete glottal closure and release (GC) and creaky voice (CV), completely irregular vibration of vocal folds (CIVV) was also observed. CV was characterized by a low fundamental frequency, a semi-periodic waveform and a decreasing intensity level, while no fundamental frequency, an aperiodic waveform and a descending intensity level characterized CIVV. The majority of GS presence was observed where a derivational prefix and a base had conjoined (11.9% GC, 27.38% CV and 55.95% CIVV). The significant outcome of data analysis in other morpheme boundaries and in simple words showed that GS did not exist/insert in hiatus in a great number of data; in 77.30% of isolated tokens and in 79.71% of in-the-context tokens two neighboring vowels in sequence were observed showing formant transition. This considerable number of data demonstrated that in standard formal Persian it is more probable to have two adjacent vowels in simple words and in morphological boundaries (except in derivational prefix + base environment) than to insert a GS.

Vowel-related tongue movements in speech: Straight or curved paths? (L)

This paper examines tongue movements between the two vowels in sequences of vowel-labial consonant-vowel, addressing the question whether the movement is a straight line or a curved path. Native speakers of Japanese and Italian served as subjects. The linguistic material consisted of words where the bilabial consonant was either long or short. The inclusion of words with different consonant lengths was motivated by earlier findings that the tongue movement is often longer when the consonant is long, which may be due to a more curved movement path. Tongue movements were recorded using a three-transmitter magnetometer system. To assess the movement path, the movement magnitude was calculated in two ways, as a straight line, the Euclidean distance, and as the actual path, obtained by summing the individual Euclidean distances between successive samples from movement onset to offset. The ratio between the path and the Euclidean distance is 1 when the movement is a straight line and greater than 1 when the path is curved. Results show that in virtually all 21 cases examined the ratio was very close to 1 and in most cases 1.2 or less. There was no reliable influence of consonant length on the ratio.

Vowel and vowel sequence processing by cochlear nucleus neurons

This study examined neuronal discharge rates and temporal patterns to vowels and vowel sequences in chinchilla. The properties of primary-like, chopper, and onset neurons were studied using vowels /i/, /a/, and /u/ individually and paired with separations (0–100 ms), at sound levels above and below thresholds. The interspike interval, period, and post-stimulus-time histograms of all neuronal types to a vowel were modified when in a sequence. Primary-like and chopper discharges were reduced and enhanced depending on vowel sequence parameters; onset neurons exhibited discharge rate reductions only and not enhancements. In addition to rate changes, novel discharge intervals appeared with vowel pairs. An unexpected finding on choppers was that subthreshold levels of the preceding vowel in a paired sequence enhanced discharges to the succeeding one. Reducing levels of preceding or increasing levels of following vowels evoked changes not predictable from single vowel data. Thus the responses to paired vowels in a sequence are interactive. Patterns of discharges and rate functions to vowel sounds from neurons of the same type varied greatly. The cochlear nuclei harbor anatomically and functionally diverse neurons. Because of this heterogeneity, the neural transformations of vowel segments by all cochlear nucleus neuronal types can not be predicted from sinusoidal data.

On the Interpretation of Vowel “Quality”: The Dimension of Rounding

The usual description of vowels in respect to their “phonetic quality” requires the linguist to locate them within a so-called “vowel space,” apparently articulatory in nature, and having three dimensions labeled high-low (or close-open), front-back, and unrounded-rounded. The first two are coordinates of tongue with associated jaw position, while the third specifies the posture of the lips. It is recognized that vowels can vary qualitatively in ways that this three-dimensional space does not account for. So, for example, vowels may differ in degree of nasalization, and they may be rhotacized or r-colored. Moreover, it is recognized that while this vowel space serves important functions within the community of linguists, both the two measures of tongue position and the one for the lips inadequately identify those aspects of vocal tract shapes that are primarily responsible for the distinctive phonetic qualities of vowels (Ladefoged 1971). With all this said, it remains true enough that almost any vowel pair of different qualities can be described as occupying different positions with the space. Someone hearing two vowels in sequence and detecting a quality difference will presumably also be able to diagnose the nature of the articulatory shift executed in going from one vowel to the other.

An autosegmental approach to vowel coalescence

It is a well-known fact that languages tend to avoid vowels in hiatus. The aim of this paper is to show that resyllabification seems to be the ultimate cause for vowel coalescence processes that affect vowels in sequence. A formal, nonlinear theory will be developed that sheds some new light on language-specific as well as language-independent properties of such coalescence phenomena. This theory will be based on detailed analyses of two unrelated languages, Old Portuguese and Kasem.

Discriminate acoustic cues in vowel sequence perception

In previous reports we have described the importance of smooth pitch continuities between adjacent first formants of four synthetic vowels /i,æ,a,u/for vowel temporal order identification [Kerivan and Alfonso, J. Acoust. Soc. Am. Suppl. 1 66, S86 (1979)]. In a followup study we asked trained listeners to discriminate vowel sequences which contained differences along the following physical parameters: (1) vowel permuted order, (2) vowel and intervowel durations ranging from 15–120 ms, and (3) pitch or loudness fundamental frequency contours, natural versus flat. Using a variable standard the task was to decide whether a “comparison” sequence was in any way different from a “standard” sequence. Preliminary results indicate that listeners can reliably discriminate (d′ = 1.0) natural from flat pitch contours of vowels in sequence at vowel durations as brief as 30 ms. They can also discriminate placement of a 15 or 30 ms intervowel duration in a given sequence at similar performance levels. Vowel permuted order effects were minimal, a finding that sharply contrasts with identification of vowels in sequence. The temporal processing capabilities of trained listeners appear sufficient to discriminate dynamic ms-level changes in pitch, loudness and duration cues of very brief vowel spectra. [Work partially supported by an NINCDS NIH grant awarded to Haskins Laboratories and the University of Connecticut Research Foundation].

Acoustic cues in the identification of vowel sequences

We have observed that at 30‐ and 60‐ms durations some permuted orders of 4 synthetic vowels /i, æ, a, u/ were much more identifiable than others using a single sequence method [Kerivan, Alfonso, and Bornstein, J. Acoust. Soc. Am. Suppl. 1 65, S113(A) (1979)]. Also, significant improvements in identification of difficult sequences occurred when silent gaps were placed between selected vowels resulting in a rhythmic grouping of the sequence. These findings have been correlated to the various acoustic parameters used to synthesize the vowels. The results of these multiple correlations show that the identification of vowels in sequence follows the laws of pitch continuity established by numerous investigators using tonal sequences. The more monotonic pitch continuity displayed by adjacent first formants the better is sequence identification. A similar but weaker correlation was found between sequence identification and pitch proximity of fundamental frequencies. An interaction was also found between pitch and loudness of adjacent fundamental and formant frequencies. The relative intensity differences for all first formants were within 3 dB; however, those for fundamental frequencies were as disparate as 11 dB. It appears that the ear primarily tracks the first formant of each vowel complex in determining vowel identity in the sequence. [Work supported by an NINCDS NIH grant awarded to Haskins Laboratories and the University of Connecticut Research Foundation.]