Acoustic Correlates Research Articles

Pharyngealization in Tashlhiyt from kinematic and acoustic perspectives

This study investigated the implementation of pharyngealization in Tashlhiyt, across various linguistic contexts VCV, VCCV, VCCV, and VCCCV. We analyzed articulatory and acoustic data from six male speakers who produced real words containing these sequences with both plain ([d, z]) and pharyngealized target consonants ([dˤ, zˤ]). The investigation comprised dynamic analyses of kinematic and formant trajectories, as well as acoustic parameters of consonants and intrusive schwas. While pharyngealization did not affect the tongue tip, it did lead to a significant lowering of the tongue body. This lowering was not confined solely to the target consonants but was observed in larger domains, extending up to nearly the entire VCCCV items. The primary acoustic correlate of pharyngealization was identified as a lowered F2 of vowels and intrusive schwas, while acoustic properties of consonants remained unaffected. Consistent with observations in the articulatory domain, the lowering of F2 was not restricted solely to vowels adjacent to pharyngealized coronals; instead, it extended to larger domains, even when there were intervening consonants.

Phonetic realization of the Emphasis contrast in voiceless stops by speakers of four Arabic varieties

Abstract This paper investigates the role of F2 and VOT in realization of the contrast in emphasis among speakers of Arabic varieties of the Levant (Lebanese, Syrian) and the Gulf (Saudi, Qatari). The results show that the two dialect groups systematically differ in acoustic realization of plain and emphatic voiceless stops. While Lebanese and Syrian varieties reveal the traditional pattern, in which the contrast is predominantly realized as a difference in F2 (Plain: 1808 Hz, Emphatic: 1097 Hz), Qatari and Saudi ones demonstrate a pattern with VOT as the main acoustic correlate. Plain [t] is produced with aspiration (M = 72 ms), and emphatic [tʕ] is unaspirated (M = 17 ms). The difference in F2 in the Gulf speech is, in contrast, smaller: low vowel [aː] is back in both contexts, with more retraction in the emphatic context (Plain: 1230 Hz; Emphatic: 1108 Hz).

Acoustics of the alignment of narrow focus prosody and lexical stress in native and nonnative English productions.

This study examined the acoustic correlates of the alignment between lexical stress and narrow focus prosody in English and investigated how this alignment is learned by second language learners whose native language is prosodically distinct from English. A production experiment was conducted where native English speakers and Korean learners of English were asked to read aloud sentences with a narrow focus on trisyllabic words with various stress patterns (e.g., ánimal, Novémber, submaríne). In the native English productions, the stressed syllables were characterized by either a rising F0 contour (for word-initial stress) or increased periodic energy (for word-medial and -final stress). The Korean speakers (KSs) produced stressed syllables with a rising F0 contour regardless of stress position, differing from the native speakers, and they exhibited greater periodic energy for word-medial and -final stressed syllables, similar to the native speakers. In addition, the KSs with higher English proficiency showed more native-like patterns by exhibiting a post-focus F0 drop immediately after word-initial stressed syllables. These findings are discussed in the context of existing literature and potential factors contributing to the challenges observed in L2 prosody learning.

Analyzing acoustic data with Bayesian finite mixture models: A practical introduction

Acoustic correlates of speech can present empirical distributions that create issues for the linear models we often use to analyze them. In some such cases, we have reason to believe that there are multiple distributions responsible for producing the data. One example is the distribution of voice onset time (VOT) in the phonologically voiced stop series /b,d,g/ in North American English. While more often produced as a short lag stop with a VOT near zero, it can also be produced with prevoicing. This leads to a bimodal distribution of VOT values for these segments. The first study of VOT by Lisker and Abramson (1964) wisely decided to report descriptive statistics for each of these pronunciation variants separately, recognizing that listing a single mean and range would have been a poor characterization of the data and potentially misleading to readers. This tutorial introduces Bayesian finite mixture models, which can model a dependent variable using a combination of two or more distributions. This is useful in situations like the one described above for English VOT, as having two distributions allows us to model both short-lag and prevoiced VOT values together in the same model. The tutorial begins with a brief conceptual explanation of these models, followed by a walkthrough of an analysis of simulated English VOT data using the package “brms” (Bürkner, 2017). An emphasis is placed on setting priors, especially setting informative priors for the intercepts of the two distributions.

A cross-linguistic review of citation tone production studies: Methodology and recommendations.

The study of citation tones, lexical tones produced in isolation, is one of the first steps towards understanding speech prosody in tone languages. However, methodologies for investigating citation tones vary significantly, often leading to limited comparability of tone inventories, both within and across languages. This paper presents a systematic review of research methods and practices in 136 citation tone studies on 129 tonal language varieties in China, including 99 studies published in Chinese, which are therefore not easily available to an international scientific readership. The review provides an overview of possible analytical decisions along the research pipeline, and unveils considerable variation in data collection, analysis, and reporting conventions, particularly in how f0, the primary acoustic correlate for tone, is operationalised and reported across studies. Key methodological issues are identified, including small sample sizes and inadequate transparency in communicating methodological decisions and procedure. This paper offers a clear road map for citation tone production research and proposes a range of recommendations on speaker sampling, experimental design, acoustic processing techniques, f0 analysis, and result reporting, with the goal of facilitating future tonal research and enhancing resources for underrepresented tonal varieties.

Cortical encoding of hierarchical linguistic information when syllabic rhythms are obscured by echoes

In speech perception, low-frequency cortical activity tracks hierarchical linguistic units (e.g., syllables, phrases, and sentences) on top of acoustic features (e.g., speech envelope). Since the fluctuation of speech envelope typically corresponds to the syllabic boundaries, one common interpretation is that the acoustic envelope underlies the extraction of discrete syllables from continuous speech for subsequent linguistic processing. However, it remains unclear whether and how cortical activity encodes linguistic information when the speech envelope does not provide acoustic correlates of syllables. To address the issue, we introduced a frequency-tagging speech stream where the syllabic rhythm was obscured by echoic envelopes and investigated neural encoding of hierarchical linguistic information using electroencephalography (EEG). When listeners attended to the echoic speech, cortical activity showed reliable tracking of syllable, phrase, and sentence levels, among which the higher-level linguistic units elicited more robust neural responses. When attention was diverted from the echoic speech, reliable neural tracking of the syllable level was also observed in contrast to deteriorated neural tracking of the phrase and sentence levels. Further analyses revealed that the envelope aligned with the syllabic rhythm could be recovered from the echoic speech through a neural adaptation model, and the reconstructed envelope yielded higher predictive power for the neural tracking responses than either the original echoic envelope or anechoic envelope. Taken together, these results suggest that neural adaptation and attentional modulation jointly contribute to neural encoding of linguistic information in distorted speech where the syllabic rhythm is obscured by echoes.

Vocalic and intervocalic intervals in the speech of educated Idoma speakers of English

The measurement of vocalic and intervocalic intervals, which has been proposed as a more reliable acoustic correlate of rhythm than inter-stress intervals or syllable duration, is usually not included in the description of the rhythm of Nigerian English, and little is known about how this contributes to the impression of rhythm in the speech of educated Idoma speakers of English. This study therefore investigated the speech rhythm of educated Idoma speakers of English by measuring vocalic and intervocalic intervals as acoustic correlates of speech rhythm. A carefully selected passage, read by 50 educated Idoma speakers of English, was analysed acoustically and statistically. The normalised pairwise variability index (nPVI) was employed to account for vocalic and intervocalic intervals in the speech of the participants in order show how this contributes to the impression of rhythm in their speech. The study indicated that there was no durational variability between successive vowels, in addition to low variability index values for vocalic and intervocalic intervals. These results showed syllable-timing rhythm. However, patterns from female participants along the continuum were less syllable timed than the male participants. There were also indications of sentence type variations with compound sentences, in some cases, less syllable timed than simple sentences.

A Preliminary Account of Inbreaths in Romanian Spontaneous Speech

Human speech is a blend between verbal and non-verbal vocalisations (NVVs). Based on previous studies pertaining to different research fields, this article focuses on breath intakes occurring in spontaneous speech. Classified as NVVs, alongside other phenomena such as vegetative sounds, affect bursts, onomatopoeia, filler particles and melodic utterances, inbreaths perform multiple and often cumulative roles in the discourse. Moreover, the interplay between speech planning and breathing control has been extensively researched in numerous studies. Analyses of NVVs in human speech have the potential of bridging the gap between various research domains, ranging from psycholinguistics and clinical linguistics to discourse management and speech planning, forensic voice comparison, as well as language processing. While the topic remains relatively unexplored in Romanian linguistics, our current study aims to broaden our understanding of the distribution and acoustic correlates of inbreaths in monologue speech.

An acoustic exploration of sibilant contrasts and sibilant merger in Mixean Basque

Abstract This exploratory study investigates sibilants in Mixean Low Navarrese, an endangered variety of Basque. This variety has been described with ten different contrastive sibilants: /s̻, s̺, ʃ, t͡s̻, t͡s̺, t͡ʃ, z̻, z̺, ʒ, d͡z̺/. The objective of the paper is to (a) provide a detailed description of the acoustics of Mixean sibilants, and (b) elucidate whether ten categories can be proposed based only on acoustical data, or whether fewer categories should be considered. The study is based on free-conversation data of ten subjects (three females, seven males) aged between 80 and 85 years. We analyze metrics reflecting the place of articulation (spectral moments, and especially the center of gravity (CoG)), including also the temporal dynamics of CoG (using the discrete cosine transform of CoG measurements of nine intervals of each phone). We also explore the acoustic correlates of the contrasts between (a) voiced and voiceless sounds and (b) fricative and affricate sounds. The results show that only seven categories can be proposed based on acoustic measurements. The lamino-alveolar series reliably contrasts with the rest, but the distinction does not hold between the apico-alveolar and the postalveolar series. We found minimal differences in the analysis of dynamic data, and none in the static analysis.

The Missionary Voice: Perceptions of an emerging register

In this paper, we report on what we are calling “Missionary Voice,” or a particular way of speaking characteristic to missionaries of the Church of Jesus Christ of Latter-day Saints. The first study elicits perceptions of Missionary Voice by Latter-day Saints in the Intermountain West without reference to any particular recording or person. We find a complex, multifaceted indexical field as well as potential linguistic features, uses for Missionary Voice, and speculative origins. In the second study, we play audio clips and ask listeners to identify the missionaries among them. While people did no better than chance, we zero in on certain speakers and compile a tentative list of acoustic correlates of Missionary Voice. As this is the first study on the language of Latter-day Saint missionaries, we open more questions than we answer, but we hope to show that Missionary Voice is very much a part of Latter-day Saint culture.

Multi-class identification of tonal contrasts in Chokri using supervised machine learning algorithms

This study examines and explores the effectiveness of various Machine Learning Algorithms (MLAs) in identifying intricate tonal contrasts in Chokri (ISO 639-3), an under-documented and endangered Tibeto-Burman language of the Sino-Tibetan language family spoken in Nagaland, India. Seven different supervised MLAs, viz., [Logistic Regression (LR), Decision Tree (DT), Random Forest (RF), Support Vector Machine (SVM), K-Nearest Neighbors (KNN), Naive Bayes (NB)], and one neural network (NN)-based algorithms [Artificial Neural Network (ANN)] are implemented to explore five-way tonal contrasts in Chokri. Acoustic correlates of tonal contrasts, encompassing fundamental frequency fluctuations, viz., f0 height and f0 direction, are examined. Contrary to the prevailing notion of NN supremacy, this study underscores the impressive accuracy achieved by the RF. Additionally, it reveals that combining f0 height and directionality enhances tonal contrast recognition for female speakers, while f0 directionality alone suffices for male speakers. The findings demonstrate MLAs’ potential to attain accuracy rates of 84–87% for females and 95–97% for males, showcasing their applicability in deciphering the intricate tonal systems of Chokri. The proposed methodology can be extended to predict multi-class problems in diverse fields such as image processing, speech classification, medical diagnosis, computer vision, and social network analysis.

A Cross-Language Comparative Study of English and German Vowel Space Area in Swiss German L1 Speakers

It is conventional to examine vowel systems by their acoustic correlates, specifically formants. In the International Phonetic Alphabet (IPA) vowel chart, vowels are placed according to their relative positions determined by the first two formant values. This two-dimensional plane makes possible the calculation of the articulatory working space of vowels. Variations in the size and shape of the vowel space exist across gender, dialects, and languages. The present study focuses on comparing the vowel space area (VSA) in English and German produced by native Swiss German speakers, attempting to shed light on whether VSAs differ significantly with different calculation methods cross-linguistically. Given the fact that absolute formant values vary tremendously across gender, Hertz values are converted to z-scores, allowing for more direct and meaningful comparisons. While vowel normalization mitigates gender-related differences within specific languages to a large extent, there remains a significant cross-linguistic gender difference. The results reveal that for 3- and 4-vowel space there is no significant effect in language but an effect is observed in gender and vowel combination on VSA, specifically in terms of individual area and overlapping ratio. This suggests that Swiss German speakers tend to utilize the same amount of vowel space in both languages, with the only difference being the expansion of English VSA in higher F2 dimension and lower F1 dimension, as observed across all calculation methods.

Rhythm Is a Marker of Ethnicity in Modern Hebrew: Evidence from a Perception Study and Actors' Ethnicized Portrayals.

In Modern Hebrew, only three segmental markers are typically acknowledged as ethnically conditioned, and usage of these markers has significantly decreased in second and third generation speakers. Yet the sociolinguistic situation of diverging language backgrounds of first generation speakers, compounded with ethnic segregation in housing and the workforce, seems like a fertile ground for social identification from speech. We report two studies on prosodic variation in Modern Hebrew: a perception study and a "matched-pairs" corpus study. The results of the first illustrate that even in the absence of the known segmental markers, ethnicity perception of young native speakers may still diverge between two major ethnic identities, Mizrahi (Middle Eastern) and Ashkenazi (European). The main acoustic correlate was rhythm, measured as the proportional duration of vowels in the utterance. In the second study, actors' speech rhythm was found to be modulated by their portrayed ethnic identity in the same direction, suggesting that this variable is socially salient-and for some speakers, controllable-enough to be involved in style shifting. This study joins a growing body of work illustrating that relatively mild rhythmic variation can contribute to social identification, and in the current case, also for ethnicity portrayal.

Articulatory and acoustic dynamics of fronted back vowels in American English.

Fronting of the vowels /u, ʊ, o/ is observed throughout most North American English varieties, but has been analyzed mainly in terms of acoustics rather than articulation. Because an increase in F2, the acoustic correlate of vowel fronting, can be the result of any gesture that shortens the front cavity of the vocal tract, acoustic data alone do not reveal the combination of tongue fronting and/or lip unrounding that speakers use to produce fronted vowels. It is furthermore unresolved to what extent the articulation of fronted back vowels varies according to consonantal context and how the tongue and lips contribute to the F2 trajectory throughout the vowel. This paper presents articulatory and acoustic data on fronted back vowels from two varieties of American English: coastal Southern California and South Carolina. Through analysis of dynamic acoustic, ultrasound, and lip video data, it is shown that speakers of both varieties produce fronted /u, ʊ, o/ with rounded lips, and that high F2 observed for these vowels is associated with a front-central tongue position rather than unrounded lips. Examination of time-varying formant trajectories and articulatory configurations shows that the degree of vowel-internal F2 change is predominantly determined by coarticulatory influence of the coda.

An acoustic analysis of French contrast-specific clear-speech productions

Clear speech provides insight into acoustic correlates speakers alter when attempting to increase intelligibility or enhance phonemic contrasts. The present study consists of an acoustic analysis of clearly spoken French voiced and voiceless stops, nasal and oral vowels, and front rounded and unrounded vowels. Productions were elicited using a simulated interaction between French-speaking participants and a computer program, in which participants produced casual tokens and the program ‘guessed’ with controlled responses. When the program incorrectly responded with “???” (indicating ‘What did you say?’) or a specific competitor (e.g., response reins [ʁɛ̃] ‘kidney’ to target reine [ʁɛn] ‘queen’), participants reproduced the word more clearly. The program’s responses probed at differences in speakers’ productions when responding to specific competitors versus globally attempting to increase intelligibility. Preliminary results show a general increase in prevoicing for clearly produced voiced stops. Speakers also adjust coarticulatory nasality to disambiguate CVN targets from CṼ competitors. Finally, expansion is exhibited between front rounded and unrounded vowel pairs in the F2/F3 vowel space from casual to clear; however, it is largest when the program’s response is “???”. Overall, findings suggest that speakers modify their speech differently in response to a specific competitor versus the general “???” response.

Exploring infant talker bias: Insights from remote speech perception testing

Lab studies show that infants (4- to 7-month-olds) prefer to listen to vowels with infant-like f0 and formant frequencies over those of an adult female (Masapollo et al., 2015; Polka et al., 2021). This Infant Talker Bias may facilitate infants’ mapping of articulatory gestures to acoustic correlates. In this study, 4- to 12-month-olds completed a listening preference task on the Lookit online testing platform. Across eight trials, we presented synthesized infant and adult vowel sounds (/i/ and /a/) paired with a simple animation and recorded the infant’s response via the webcam. Infant looking time and vocalization to each vowel type were coded offline. Preliminary analyses (n = 91) show that listening time increased with age (p < 0.05), and all infants listened longer to infant vowels than to adult vowels (p < 0.01). Preliminary analyses (n = 62) also show an increase in infant vocalizations with age (p = 0.00) and a trend towards more and longer vocalizations in response to the adult vowels. These findings replicate and extend the infant talker bias to new vowel stimuli and to older infants, and support the use of remote testing in infant speech perception studies.

Social evaluative implications of sensory adaptation to human voices.

People form social evaluations of others following brief exposure to their voices, and these impressions are calibrated based on recent perceptual experience. Participants adapted to voices with fundamental frequency (f o; the acoustic correlate of perceptual pitch) manipulated to be gender-typical (i.e. masculine men and feminine women) or gender-atypical (i.e. feminine men and masculine women) before evaluating unaltered test voices within the same sex. Adaptation resulted in contrastive aftereffects. Listening to gender-atypical voices caused female voices to sound more feminine and attractive (Study 1) and male voices to sound more masculine and attractive (Study 2). Studies 3a and 3b tested whether adaptation occurred on a conceptual or perceptual level, respectively. In Study 3a, perceivers adapted to gender-typical or gender-atypical voices for both men and women (i.e. adaptors pitch manipulated in opposite directions for men and women) before evaluating unaltered test voices. Findings showed weak evidence that evaluations differed between conditions. In Study 3b, perceivers adapted to masculinized or feminized voices for both men and women (i.e. adaptors pitch manipulated in the same direction for men and women) before evaluating unaltered test voices. In the feminized condition, participants rated male targets as more masculine and attractive. Conversely, in the masculinized condition, participants rated female targets as more feminine and attractive. Voices appear to be evaluated according to gender norms that are updated based on perceptual experience as well as conceptual knowledge.

Creaky voice across language and gender: A study of Canadian English-French bilingual speech

This study addresses how non-contrastive creaky voice varies among languages and across speakers (as a function of gender). Spontaneous speech from 9 English-French bilingual speakers born and raised in Ontario/Québec was collected from publicly available online data sources, amounting to roughly 5 min of speech per speaker-language pair and 13 992 vowels total. This corpus will reach 40 speakers by the conference. Acoustic analysis consisted of pitch tracking in Praat, providing a proportion of unreliable f0 tracks for each vowel as well as one spectral slope measure (H1*-H2*) and two Harmonics-to-Noise Ratios (CPP and HNR05) as acoustic correlates of creaky voice. Statistical significance was tested using mixed-effects regression models, with fixed effects of language, gender, and utterance position, and maximal by-word and by-speaker random effects. The main results for gender show that men's vowels have more unreliable f0 tracks, lower H1*-H2*, lower HNR05 and somewhat lower CPP, suggesting that male speakers are creakier overall. Regarding language, English displays more unreliable pitch tracking compared to French, providing some evidence for language-dependent vocal settings. Other acoustic correlates of creak, however, do not show consistent cross-linguistic differences.

The acoustics of Contemporary Standard Bulgarian vowels: A corpus study.

A comprehensive examination of the acoustics of Contemporary Standard Bulgarian vowels is lacking to date, and this article aims to fill that gap. Six acoustic variables-the first three formant frequencies, duration, mean f0, and mean intensity-of 11 615 vowel tokens from 140 speakers were analysed using linear mixed models, multivariate analysis of variance, and linear discriminant analysis. The vowel system, which comprises six phonemes in stressed position, [ε a ɔ i ɤ u], was examined from four angles. First, vowels in pretonic syllables were compared to other unstressed vowels, and no spectral or durational differences were found, contrary to an oft-repeated claim that pretonic vowels reduce less. Second, comparisons of stressed and unstressed vowels revealed significant differences in all six variables for the non-high vowels [ε a ɔ]. No spectral or durational differences were found in [i ɤ u], which disproves another received view that high vowels are lowered when unstressed. Third, non-high vowels were compared with their high counterparts; the height contrast was completely neutralized in unstressed [a-ɤ] and [ɔ-u] while [ε-i] remained distinct. Last, the acoustic correlates of vowel contrasts were examined, and it was demonstrated that only F1, F2 frequencies and duration were systematically employed in differentiating vowel phonemes.

Acoustics of Emphatics and Uvulars in Bedouin Hijazi Arabic

The current study examines the effects of emphatics /ðˤ sˤ tˤ/ and uvulars /ʁ χ/ on following vowels in Bedouin Hijazi Arabic. The main goal is to observe F1 and F2 of vowels /i æ u/ next to the aforementioned sounds. The outcome of this study shows that F1 and F2 values next to emphatics and uvulars are reliable acoustic correlates. Emphatics and uvulars next to vowels increase F1 values, a pattern not noticeable in vowels next to plain sounds /ð s t/. Both groups also show lower F2 values compared to plain coronals. The size of F2 decrease, however, is lower in vowels following emphatics than vowels following uvulars. Differences in F2 values between these sound groups suggest differences in their articulatory mechanisms.