Vowel Quality Research Articles

Tools for education in acoustics and phonetics

We have developed a series of tools for education in acoustics and phonetics. Some of them are in electronic form, while some are physical models. A set of demonstrations and explanations in acoustic phonetics is now available as “Acoustic-Phonetics Demonstrations (APD)” through our WebSite: www.splab.net/APD/. We are adding content and have made YouTube video clips using physical models available on our WebPages. In particular, we use the physical models of the human vocal tract to demonstrate acoustic phenomena and theories. They are useful tools for explaining acoustics in speech production, such as the source-filter theory and the relationship between vocal-tract configurations and vowel quality. Furthermore, the models are effective when teaching articulation/pronunciation of native and non-native languages. Due to the high demand for vocal-tract models of various sounds in multiple languages, we are expanding the range of sounds to include more than Japanese sounds, but also additional vowels and consonants in different languages, including English. We also discuss how to apply three-dimensional printing.

Effects of phonetic naturalness in decay of Korean vowel harmony

In this paper, based on Korean vowel qualities measured in the production experiments, I point out that /o/-stems are also actively participating in the decay of Korean vowel harmony, and their speed of decay is much faster than /a/-stems' speed. How the late-starter /o/-stems could have the faster speed in the decay of Korean vowel harmony? The role of phonetic naturalness in language learning is the key. Measured vowel qualities show that /o/ is acoustically much closer to /ʌ/ as “disharmonic” pair than to /a/ as “harmonic” pair. In addition, in terms of articulatory, the raising of /o/ and the backing of /ʌ/ make them more similar. In the production experiments, 14 Seoul-Korean speakers participated (7 males, 7 females). Onset and coda of stems are controlled. For each condition, 1 existing word and 2 nonce words are used. Participants are asked to make a natural conjugation form of a given stem and to produce it three times. Unlike previous corpus and production studies reporting that /o/-stems show no disharmonic forms, the current experimental results show that quality of selected vowels after /o/-stems is similar to /ʌ/, not /a/. Compared to /a/-stems, /o/-stems' suffix vowel qualities are clearly closer to /ʌ/.

Temporal and spectral characteristics of the intervocalic consonant clusters in Korean

Park(2008) showed that there is no significant difference in specific segment duration and their temporal structure between VCC[Asp]V and VC[Asp]V, and between VCC[For]V, VCC[Len]V, and VC[For]V, where V stands for vowel, C for consonant, [Asp] for aspirated, [For] for fortis, and [Len] for lenis. He also showed that there is no significant difference in consonant duration between a singleton and a geminate when the following C is [For] or [Asp], but a significant difference between them when the following C is [Len]. On the other hand, Park(2005) showed that there is a significant difference in phonation type index k (PTI k) across consonant types, where PTI k presents a single and simplified measure of the spectral tilt, which is free from the effects of fundamental frequency and vowel quality. This study, by applying Park(2008)’s and Park(2005)’s methods, investigates temporal and spectral characteristics of the consonant clusters of the other manners and places of articulation. The results showed that temporal characteristics present a similar pattern to those of Park(2008), and that spectral characteristics are associated with the phonation identity of the final consonant of the intervocalic consonant clusters.

Acoustics of epenthetic vowels in Brazilian Portuguese

In this production study involving a task of real words and a task of nonce words, epenthesis in obstruent-obstruent clusters in Brazilian Portuguese was investigated and the acoustic properties of epenthetic and lexical [i] were compared. A number of linguistic factors were found to be significant predictors of the epenthesis rate: voicing of the consonants of the cluster, manner of articulation of the second consonant, place of articulation of both consonants, and position of the cluster with respect to the stressed syllable. Moreover, there was a higher epenthesis rate for nonce words than for real words. As for the quality of the epenthetic vowel, it was found to have the same F1 as the lexical [i] in the language, but it was significantly shorter in duration, and it had a significantly lower F2 in the nonce words, but not in the real words. Finally, we found a relatively high rate of deletion of lexical [i], conditioned by the same factors that conditioned epenthesis rate, but in the opposite direction. It is concluded that epenthesis is a phonological phenomenon in Brazilian Portuguese, but that there is also acoustic reduction in the language that affects both lexical and epenthetic vowels.

Acoustic characteristics of liquid geminates in Japanese

Japanese contrasts consonant length. Much research has been done on the acoustic characteristics of obstruent geminates in Japanese, identifying the constriction duration as the primary acoustic correlate. The ratios of the duration of the consonants and the surrounding vowels have also been investigated, and it was pointed out that the ratios differ from some other languages with distinctive consonant length, such as Italian. The present study examines the acoustics of liquid geminates in Japanese. Phonological phenomena in Japanese such as verb inflection demonstrate that the language dislikes liquid geminates. However, while not as common as obstruent or nasal geminates, liquid geminates are not impossible; they are present in certain loanwords and emphatic expressions. I report on the acoustic correlates of liquid geminates focusing on consonant sonority and consonant-vowel ratio, in three environments controlled for vowel quality and pitch-accent position: namely, loanwords (mostly from Italian and Arabic), emphatic forms of adjectives (e.g., karai “spicy” > karrai) and emphatic forms of onomatopoeic expressions (e.g., garagara “expresses emptiness” > garragara), pronounced by three native speakers of Tokyo dialect of Japanese in laboratory settings.

Investigating patterns of vowel production using real-time magnetic resonance imaging

Characteristic tongue postures of 21,478 vowels produced by four speakers of General American English were compared in lexically stressed and unstressed positions to examine patterns of articulation and reduction. Image frames capturing midsagittal vocal tract configurations were reconstructed at the acoustic midpoint of each vowel produced in a 3,450 word forced-aligned transcribed speech corpus (Narayanan et al. 2014). Sixty image sets were constructed, consisting of all exemplars of each contrastive vowel quality of American English, as produced by each speaker: up to 1049 tokens of the most frequent vowel /i/, and 48 tokens of the least frequent vowel /ɔɪ/. Image frames were cropped to a region of interest centred on the tongue dorsum, and linearized into one-dimensional vectors in which pixel intensity corresponds to presence of soft tissue. Principle components analysis was applied to each set of image vectors to examine the distribution and variability of tongue tissue associated with each vowel posture. “Eigentongues” were constructed from the most significant components in each image set (Sirovich & Kirby 1987; Hueber et al. 2007), resulting in a set of images characterizing each speakers’ vowel space, produced in both lexically stressed and unstressed positions.

For bilinguals, Enxet vowel spaces smaller than Spanish

This study compares the vowel spaces of bilingual speakers of Spanish and Enxet Sur (ISO 639-3: enx), a moderately threatened language spoken by around 4000 speakers in the Paraguayan Chaco which purportedly lacks high vowels. The Enxet vowel system has only three phonemic vowel qualities /e,a,o/ and a length distinction. Using recorded natural speech data from two Enxet/Spanish bilinguals, formant values for vowel tokens are used to establish phonetic targets and acoustic vowel clouds for each of the phonemic vowels in both languages. A comparison of these vowel spaces suggests that an individual bilingual speaker uses a smaller vowel space when speaking Enxet (less vowel height, higher minimum F1 frequencies) than when speaking Spanish. Languages like Enxet lacking in true high vowels present problems for the theory of adaptive dispersion in that they do not “take advantage” of maximal distinctiveness in the acoustic and articulatory quality of their vowels. This is the first known phonetic investigation of an Enlhet-Enenlhet language.

Tenseness in Northern Yi: An ultrasonic and acoustic study

A contrast between tense and lax vowels is a main feature of many Tibeto-Burman (TB) languages spoken in Southwest China. This study investigated the articulation and acoustics of tense-lax contrast in two Northern Yi dialects: Suondi and Yinuo. Both dialects have five pairs of phonologically-defined tense and lax vowels. Previous studies have shown that tense and lax vowels in TB had distinct patterns in phonation types and f0, while the difference in other acoustic dimensions—vowel quality, duration, and intensity are rarely examined, and the difference in the lingual gestures is largely unknown. The current study examined the articulatory and acoustic characteristics of tense-lax contrast using ultrasound imaging and spectrogram analysis. Our preliminary results showed that articulatorily, tense vowels were produced with more retracted tongue root. Acoustically, tense vowels had higher F1 and lower F2, which was caused by the lowered and retracted tongue position. The intensity of tense vowels was lower than that of lax vowels for front vowels. No significant difference was found in duration. Based on the articulatory and acoustic data, as well as the vowel harmony phenomenon in Yi, we propose that the tense-lax distinction in Northern Yi can be better represented as [+RTR] phonologically.

How listeners recognise vowel sounds under highpass or lowpass filtering of vowel-specific frequency ranges

The present paper reports findings of two experiments on filtered sounds of the Standard German vowels /i-y-e-o-ɛ-a-o-u/ produced by a female speaker at two fundamental frequencies fo = 220 Hz and 659 Hz and a male speaker at fo = 131 Hz and 523 Hz. High-pitched sounds were included in order to account for a possible impact of the fo level on the perception of filtered vowel sounds. In the first experiment, the frequency region of the first formant of the sounds was highpass filtered, and in the second experiment, the frequency region of the second formant of the sounds was lowpass filtered. Vowel recognition of all sounds was investigated in a listening test. Results revealed shifts in the perceived vowel quality which varied across (i) vowel categories, (ii) fo , and (iii) filter cutoff frequencies. Details of the filter parameters and of the perceived vowel quality shifts are given in the paper and implications for the relationship between acoustic cues and vowel recognition are discussed.

A Variationist Approach to Nigerian English Phonology

Since the Phonology of Nigerian English has been described variously by different researchers this paper sought toexplained the features of Nigerian English from the perspectives of the sociolinguistic variables of age, sex,occupation, education, exposure and motivation. The study examined the factors that underscore the social andethnic variables exhibited by Educated Nigerians in their attempt to use the English language efficiently at thephonological level. The theoretical framework for this study wasthe adapted synthesis of ascribed and acquiredsociolinguistic variables according toLabov (1966) and Preston (1989). The data for the study were elicited fromover a hundred speakers of English selected along the lines of the different variables earlier mentioned. Their voiceswere recorded and their renditions were phonemically transcribed in the A.C. Gimson’s model of transcription andacoustically analyzed using the Pratt software. The findings in the study suggest among others that adult speakers ofEnglish in Nigeria perform better in approximation to Standard British English. It also reveals that the vocalic systemin Hausa, Yoruba and Igbo languages shares slightly,lengthening of English vowel quality as demonstrated by oursubjects.Some Nigerian Female speakers of English tend to devoice voiced consonants in their speeches. On thewhole, we concluded that all the sociolinguistic variables best explain the differences and the features in the qualityof speech sounds observed among Nigerian speakers of English.

Sociophonetic variation of like in British dialects: effects of function, context and predictability

This study examines sociophonetic variation in different functions oflikeamong adolescents in London and Edinburgh. It attempts to determine the factors that may explain this variation. Our results suggest that the function oflikecorrelates primarily with contextual factors, rather than the phonetic factors of vowel quality, /l/ to vowel duration and /k/ realisation. In particular, the preceding and following segments and their bigram predictability emerge as highly significant, in addition to the boundary strength followinglike. In both London and Edinburgh, the vowel appears to be the only non-contextual feature that is sensitive to the function oflike: quotativebe likeis more likely to be monophthongised than other functions oflike. We argue that the more monophthongal nature of quotativelikeis due to the syntactic and prosodic context in which it occurs.

The role of vowel quality in ELF misunderstandings

Abstract Misunderstandings are natural occurrences in conversation. Though they are the exception to the norm, and furthermore they do not necessarily result in communication breakdown, they do sometimes occur, and it is important to find out what causes them. Deterding (2013. Misunderstandings in English as a lingua franca: An analysis of ELF interactions in South-East Asia. Berlin & New York: Mouton de Gruyter.) investigates misunderstandings in English as a Lingua Franca (ELF) in data from the Asian Corpus of English (ACE) and discusses the role of phonological, lexical and grammatical features in causing them to occur. He reports that over 86 % of the tokens of misunderstandings in his corpus involve pronunciation. The current paper analyses this data further, specifically to determine the role of vowels, as Jenkins (2000. The phonology of English as an international language. Oxford: Oxford University Press.) has suggested that vowel quality is not important in English as a Lingua Franca, so she excludes vowel quality from the Lingua Franca Core, the set of pronunciation features that she suggests are important for maintaining intelligibility in an international setting. In fact, a total of over half the tokens of misunderstanding listed in Deterding’s Misunderstandings in English as a Lingua Franca involve the quality of vowels, though in many cases this appears to be a minor factor. The current paper analyses these 98 tokens involving vowel quality in detail, to find out if some shifts in vowel quality are more important than others, and to investigate if vowel quality really is unimportant for intelligibility in English as a Lingua Franca. It was found that vowel quality rarely causes a problem, and only in one token, in which the speaker was making a joke, is vowel quality the main factor causing the misunderstanding.

Stylistic Variation in Heritage Spanish Vowel Production

While recent studies of Spanish vowels produced by heritage speakers of Spanish (HSS) have revealed important differences in acoustic distribution and unstressed vowel reduction in comparison to monolingual norms (Alvord & Rogers, 2014; Boomershine, 2012; Ronquest, 2013; Willis, 2005), the influence of speech style on vowels produced by HSS remains relatively unexplored. Previous research examining stylistic variation in monolingual and bilingual varieties of Spanish report vowel space expansion in controlled speech relative to spontaneous speech (Alvord & Rogers, 2014; Harmegnies & Poch-Olivé, 1992; Poch-Olivé, Harmegnies, & Martín Butragueño, 2008) and increased vowel duration (Bradlow, 2002), although many of these studies included a small number of participants or did not examine the entire vowel system. The present investigation extends previous research by including a larger number of speakers and three novel tasks, as well as examining the effects of style on both quality and duration throughout the system as a whole. Acoustic and statistical analyses confirmed an overall vowel space expansion effect in controlled speech similar to that reported in previous studies, although not all vowels varied equally and along the same dimensions. Furthermore, vowel duration exhibited less variation than expected and was limited to the lowest vowels, suggesting that vowel quality and duration may be affected independently of one another. Combined, the general results not only reveal that speech style has a similar impact on vowels produced by HSS and other bilingual and monolingual populations, but also emphasize the importance of analyzing the entire vowel system on multiple dimensions.

Native English Speakers’ Perception of Arabic Emphatic Consonants and the Influence of Vowel Context

AbstractNative English speakers experience difficulty acquiring Arabic emphatic consonants. Arabic language textbooks have suggested that learners focus on adjacent vowels for cues to these consonants; however, the utility of such a strategy has not been empirically tested. This study investigated the perception of Arabic emphatic‐plain contrasts by means of cross‐language vowel identification and perceptual discrimination tasks. It was found that native English speakers relied more on following vowels than on the consonants themselves when discriminating Arabic emphatic and plain consonants, and that their accuracy was greatest when the following vowel was /æ/, followed by /u/ and /i/. The cross‐language vowel identification task revealed that Arabic /æ/ was identified as a systematically different English vowel (/ɑ/) when following emphatics than when following plain consonants (/æ/), while Arabic /i/ and /u/ failed to exhibit a differential identification pattern. Together these findings indicate that following vowel quality moderates Arabic emphatic consonant perception by English speakers, who may exploit their sensitivity to the English /ɑ/‐/æ/ contrast to perceive emphatic‐plain contrasts in the context of Arabic /æ/. However, such a strategy is less likely to be successful when the following vowel is /i/ or /u/. Implications and pedagogical suggestions for the teaching of Arabic to native speakers of English are offered.

Co-articulatory Cues for Communication: An Investigation of Five Environments

We hypothesized that speakers adjust co-articulation in vowel–consonant (VC) sequences in order to provide listeners with enhanced perceptual cues to C, and that they do so specifically in those situations where primary cues to C place of articulation tend to be diminished. We tested this hypothesis in a speech production study of American English, measuring the duration and extent of VC formant transitions in five conditioning environments – consonant voicing, phrasal position, sentence accent, vowel quality, and consonant place – that modulate primary cues to C place in different ways. Results partially support our hypothesis. Although speakers did not exhibit greater temporal co-articulation in contexts that tend to diminish place cues, they did exhibit greater spatial co-articulation. This finding suggests that co-articulation serves specific communicative goals.

Preliminary Experiments on Human Sensitivity to Rhythmic Structure in a Grammar with Recursive Self-Similarity.

Preliminary Experiments on Human Sensitivity to Rhythmic Structure in a Grammar with Recursive Self-Similarity.

Resolving the Issue of the Target of Vowel Copy in Fijian Loanwords

English loanwords into Fijian undergo vowel epenthesis, as Fijian disallows coda consonants and consonant clusters. Vowel copy is an option for determining epenthetic vowel quality in loanword adaptation (Kumagai 2016a; Schütz 1978, 2004). The target of copy epenthesis seems to be either the preceding or following vowel of the epenthetic site. However, the choice of target vowel is indeterminate, as there is no vowel copy in Fijian native phonology. This paper offers a resolution to the problem by adopting an expanded version of prosodic projection theory (Martínez-Paricio 2012, 2013), in which feet are allowed to exhibit maximal/minimal projection. I propose Foot Condition, which requires the Foot[±max/±min] to circumscribe the vowel copy domain.

Auditory event-related responses to diphthongs in different attention conditions

The modulation of auditory event-related potentials (ERP) by attention generally results in larger amplitudes when stimuli are attended. We measured the P1-N1-P2 acoustic change complex elicited with synthetic overt (second formant, F2Δ=1000Hz) and subtle (F2Δ=100Hz) diphthongs, while subjects (i) attended to the auditory stimuli, (ii) ignored the auditory stimuli and watched a film, and (iii) diverted their attention to a visual discrimination task. Responses elicited by diphthongs where F2 values rose and fell were found to be different and this precluded their combined analysis. Multivariate analysis of ERP components from the rising F2 changes showed main effects of attention on P2 amplitude and latency, and N1-P2 amplitude. P2 amplitude decreased by 40% between the attend and ignore conditions, and by 60% between the attend and divert conditions. The effect of diphthong magnitude was significant for components from a broader temporal window which included P1 latency and N1 amplitude. N1 latency did not vary between attention conditions, a finding that may be related to stimulation with a continuous vowel. These data show that a discernible P1-N1-P2 response can be observed to subtle vowel quality transitions, even when the attention of a subject is diverted to an unrelated visual task.

Contrastive foot structure in Franconian tone-accent dialects

Franconian has a contrast between two tone accents, commonly referred to as Accent 1 and Accent 2. Traditional autosegmental analyses of the phenomenon suggest that this opposition derives from the presence of lexical tone. In contrast to this ‘tonal approach’, I argue that the Franconian accent contrast is based on contrastive foot structure – there is no tone in the lexicon. This ‘metrical approach’ not only accounts for the tonal differences between the accents, but also captures a variety of facts that are hard to incorporate into a synchronic tonal analysis, involving morphological alternations between Accent 1 and Accent 2, as well as the effects of vowel duration, vowel quality and consonant quality on accent-class membership. The metrical analysis of these patterns is in line with similar approaches to tone-accent contrasts in North Germanic and Scottish Gaelic.

Vowel discrimination asymmetry: The influence of token variability and lexical characteristics

Listeners are more sensitive to changes in vowel quality when a peripheral vowel rather than a central vowel serves as deviant in an oddball paradigm (asymmetry in vowel discrimination). Schwartz et al. (2005) hypothesized that formant focalization in peripheral vowels make them perceptually more salient than central ones. Interestingly, however, a neurophysiological study (García and Froud, 2014) suggested that lexical familiarity may play a role in this perceptual asymmetry. This study investigated whether or not the asymmetry in vowel discrimination is mediated by the lexical characteristics of the stimulus words. Using an oddball paradigm, mismatch negativity (MMN) responses were elicited from adult monolingual American English listeners using naturally-produced American English vowel contrast /ɑ/-/ʌ/ in a real-word pair (Dock/Duck) and a non-word pair (Dop/Dupp). Listeners heard the pairs in two sessions. It was hypothesized that the MMN responses would be observed only when the peripheral vowel /ɑ/ in real words serves as deviant. Preliminary results suggest that MMN responses were observed for /ɑ/ but not for /ʌ/ regardless of the lexical status of the stimulus words. The implications of findings will be discussed in terms of the effects of lexical status of stimulus words and token variability in vowel discrimination.