Formant Space Research Articles

Acoustic measurements of the Indonesian oral monophthongs produced by Acehnese speakers

This study explores the characteristics of Indonesian oral monophthong vowels produced by male and female language consultants in Banda Aceh, Indonesia, as their first language. Using purposive sampling, ten Acehnese males and ten Acehnese females were selected to articulate eight target vowels: /i/, /e/, /ɛ/, /ә/, /a/, /u/, /o/, and /ɔ/. Vowel measurements were obtained through recorded word elicitation, using a word list containing the target vowels. F1 and F2 frequencies in Hertz were determined and analyzed using Praat software to assess vowel qualities and subsequently converted to the Bark scale. Vowels were plotted on the F1/F2 formant space. The findings illustrate the distinct measurements of each Indonesian monophthong vowel by male and female consultants, represented in the vowel space. Male vowels generally exhibit higher and more centralized positioning, while female vowels appear more dispersed and lower. This research contributes valuable insights for comparing vowel systems across various languages and dialects spoken in multilingual Indonesia.

The effect of aging on vowel production in Western Canadian English

Aging influences many aspects of speech production. For example, a speaker’s fundamental frequency or formant space has been reported to change as they age. However, this research has largely focused on careful or prepared speech, with a few notable exceptions in the longitudinal research literature. There is limited knowledge of the relationship between aging and vowel reduction in spontaneously produced speech. It is important to investigate how spontaneous everyday speech is influenced by the aging process. In the present investigation, we work with a corpus of Western Canadian English containing spontaneous conversational speech produced by 18 younger (17–31) and 13 older speakers (64–79). The data was force-aligned and then acoustic measures were extracted from the aligned data. In this presentation, we report on the differences in formant space for stressed and unstressed vowels. The results of this study will be used to better inform our understanding of the role of vowel centralization and aging in spontaneous speech. They will further support the understanding of reduction in spontaneous speech.

Correction: 'Chimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage' (2021), by Grawunder et al.

Correction: 'Chimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage' (2021), by Grawunder et al.

Chimpanzees Have no Expanded Formant Space and No Correlated F1 and F2: A Comment on Grawunder et al. (2021)

Chimpanzees Have no Expanded Formant Space and No Correlated F1 and F2: A Comment on Grawunder et al. (2021)

Editor's note: Chimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage.

Editor's note: Chimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage.

Vowel and formant representation in the human auditory speech cortex

Vowels, a fundamental component of human speech across all languages, are cued acoustically by formants, resonance frequencies of the vocal tract shape during speaking. An outstanding question in neurolinguistics is how formants are processed neurally during speech perception. To address this, we collected high-density intracranial recordings from the human speech cortex on the superior temporal gyrus (STG) while participants listened to continuous speech. We found that two-dimensional receptive fields based on the first two formants provided the best characterization of vowel sound representation. Neural activity at single sites was highly selective for zones in this formant space. Furthermore, formant tuning is adjusted dynamically for speaker-specific spectral context. However, the entire population of formant-encoding sites was required to accurately decode single vowels. Overall, our results reveal that complex acoustic tuning in the two-dimensional formant space underlies local vowel representations in STG. As a population code, this gives rise to phonological vowel perception.

Production and perception of prevelar merger: Two-dimensional comparisons using Pillai scores and confusion matrices

Vowel merger production is quantified with gradient acoustic measures, while phonemic perception methods are often coarser, complicating comparisons within mergers in progress. This study implements a perception experiment in two-dimensional formant space (F1 × F2), allowing unified plotting, quantification, and statistics with production data. Production and perception are compared within 20 speakers for a two-part prevelar merger in progress in Pacific Northwest English, where mid-front /ɛ, e/ approximate or merge before voiced velar /ɡ/ (leg–vague merger), and low-front prevelar /æɡ/ raises toward them (bag-raising). Distributions are visualized with kernel density plots and overlap quantified with Pillai scores and confusion matrices from linear discriminant analysis models. Results suggest that leg–vague merger is perceived as more complete than it is produced (in both the sample and community), while bag-raising is highly variable in production but rejected in perception. Relationships between production and perception varied by age, with raising and merger progressing across two generations in production but not perception, followed by younger adults perceiving leg–vague merger but not producing it and varying in (minimal) raising perception while varying in bag-raising in production. Thus, prevelar raising/merger may be progressing among some social groups but reversing in others.

Expression of concern: 'Chimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage' (2022) by Grawunder et al.

Open AccessMoreSectionsView PDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmail Cite this article Grawunder Sven, Uomini Natalie, Samuni Liran, Bortolato Tatiana, Girard-Buttoz Cédric, Wittig Roman M. and Crockford Catherine 2023Expression of concern: ‘Chimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage’ (2022) by Grawunder et al.Phil. Trans. R. Soc. B3782022047620220476http://doi.org/10.1098/rstb.2022.0476SectionOpen AccessEditorialExpression of concern: ‘Chimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage’ (2022) by Grawunder et al. Sven Grawunder Sven Grawunder Google Scholar Find this author on PubMed Search for more papers by this author , Natalie Uomini Natalie Uomini http://orcid.org/0000-0002-9898-6415 Google Scholar Find this author on PubMed Search for more papers by this author , Liran Samuni Liran Samuni Google Scholar Find this author on PubMed Search for more papers by this author , Tatiana Bortolato Tatiana Bortolato Google Scholar Find this author on PubMed Search for more papers by this author , Cédric Girard-Buttoz Cédric Girard-Buttoz Google Scholar Find this author on PubMed Search for more papers by this author , Roman M. Wittig Roman M. Wittig http://orcid.org/0000-0001-6490-4031 Google Scholar Find this author on PubMed Search for more papers by this author and Catherine Crockford Catherine Crockford http://orcid.org/0000-0001-6597-5106 Google Scholar Find this author on PubMed Search for more papers by this author Sven Grawunder Sven Grawunder Google Scholar Find this author on PubMed Search for more papers by this author , Natalie Uomini Natalie Uomini http://orcid.org/0000-0002-9898-6415 Google Scholar Find this author on PubMed Search for more papers by this author , Liran Samuni Liran Samuni Google Scholar Find this author on PubMed Search for more papers by this author , Tatiana Bortolato Tatiana Bortolato Google Scholar Find this author on PubMed Search for more papers by this author , Cédric Girard-Buttoz Cédric Girard-Buttoz Google Scholar Find this author on PubMed Search for more papers by this author , Roman M. Wittig Roman M. Wittig http://orcid.org/0000-0001-6490-4031 Google Scholar Find this author on PubMed Search for more papers by this author and Catherine Crockford Catherine Crockford http://orcid.org/0000-0001-6597-5106 Google Scholar Find this author on PubMed Search for more papers by this author Published:26 December 2022https://doi.org/10.1098/rstb.2022.0476This article comments on the followingResearch ArticleChimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineagehttps://doi.org/10.1098/rstb.2020.0455 Sven Grawunder, Natalie Uomini, Liran Samuni, Tatiana Bortolato, Cédric Girard-Buttoz, Roman M. Wittig and Catherine Crockford volume 377issue 1841Philosophical Transactions of the Royal Society B: Biological Sciences15 November 2021Phil. Trans. R. Soc. B377, 2020045. (Published online 15 November 2021) (https://doi.org/10.1098/rstb.2020.0455)Following the publication of ‘Chimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage’ Phil. Trans. R. Soc. B377: 20200455 (Published online: 15 November 2021), it has been brought to the attention of the Editorial team that there are concerns regarding this study.An investigation into these aspects is under way, and the journal is, therefore, issuing an expression of concern and will notify readers as to the results of our investigation as soon as possible. Previous ArticleNext Article VIEW FULL TEXT DOWNLOAD PDF FiguresRelatedReferencesDetailsRelated articlesChimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage15 November 2021Philosophical Transactions of the Royal Society B: Biological Sciences This Issue13 February 2023Volume 378Issue 1870Theme issue ‘Concepts in interaction: social engagement and inner experiences’ compiled and edited by Anna M. Borghi, Albertyna Osinska, Andreas Roepstorff and Joanna Raczaszek-Leonardi Article InformationDOI:https://doi.org/10.1098/rstb.2022.0476PubMed:36571115Published by:Royal SocietyPrint ISSN:0962-8436Online ISSN:1471-2970History: Manuscript received23/11/2022Manuscript accepted23/11/2022Published online26/12/2022Published in print13/02/2023 License:© 2022 The Authors.Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the original author and source are credited. Citations and impact Subjectsbehaviourevolution

Vowel convergence does not affect auditory speaker discriminability in humans and machine in a case study on Swiss German dialects

In this study, we examined whether the convergence in interlocutors’ vowel acoustics leads to decreasing discriminability between interlocutors’ voices. Ten pairs of Grison and Zürich German speakers produced lexical items before and after dialogue interactions with evidence of vowel convergence in post-dialogue productions. In Experiment 1, native and non-native Swiss German listeners discriminated pairs of speakers whose speech was obtained pre- and post-dialogue. Results showed that listeners’ sensitivity (A’) was higher for native than non-native listeners, but comparable for pre- and post-dialogue recordings. The observed negative correlation between voice discrimination and the acoustic distance in formant space was mainly driven by a single speaker pair. In Experiment 2, the speaker recognition performance of an i-vector-based software was compared in pre- and post-dialogue speech. Results revealed no difference in the system performance between the two conditions. The findings suggest that vowel convergence does not compromise voice discriminability under the given experimental conditions.

Perturbing the consistency of auditory feedback in speech.

Sensory information, including auditory feedback, is used by talkers to maintain fluent speech articulation. Current models of speech motor control posit that speakers continually adjust their motor commands based on discrepancies between the sensory predictions made by a forward model and the sensory consequences of their speech movements. Here, in two within-subject design experiments, we used a real-time formant manipulation system to explore how reliant speech articulation is on the accuracy or predictability of auditory feedback information. This involved introducing random formant perturbations during vowel production that varied systematically in their spatial location in formant space (Experiment 1) and temporal consistency (Experiment 2). Our results indicate that, on average, speakers’ responses to auditory feedback manipulations varied based on the relevance and degree of the error that was introduced in the various feedback conditions. In Experiment 1, speakers’ average production was not reliably influenced by random perturbations that were introduced every utterance to the first (F1) and second (F2) formants in various locations of formant space that had an overall average of 0 Hz. However, when perturbations were applied that had a mean of +100 Hz in F1 and −125 Hz in F2, speakers demonstrated reliable compensatory responses that reflected the average magnitude of the applied perturbations. In Experiment 2, speakers did not significantly compensate for perturbations of varying magnitudes that were held constant for one and three trials at a time. Speakers’ average productions did, however, significantly deviate from a control condition when perturbations were held constant for six trials. Within the context of these conditions, our findings provide evidence that the control of speech movements is, at least in part, dependent upon the reliability and stability of the sensory information that it receives over time.

Understanding Design Features of Music and Language: The Choric/Dialogic Distinction.

Music and spoken language share certain characteristics: both consist of sequences of acoustic elements that are combinatorically combined, and these elements partition the same continuous acoustic dimensions (frequency, formant space and duration). However, the resulting categories differ sharply: scale tones and note durations of small integer ratios appear in music, while speech uses phonemes, lexical tone, and non-isochronous durations. Why did music and language diverge into the two systems we have today, differing in these specific features? We propose a framework based on information theory and a reverse-engineering perspective, suggesting that design features of music and language are a response to their differential deployment along three different continuous dimensions. These include the familiar propositional-aesthetic (‘goal’) and repetitive-novel (‘novelty’) dimensions, and a dialogic-choric (‘interactivity’) dimension that is our focus here. Specifically, we hypothesize that music exhibits specializations enhancing coherent production by several individuals concurrently—the ‘choric’ context. In contrast, language is specialized for exchange in tightly coordinated turn-taking—‘dialogic’ contexts. We examine the evidence for our framework, both from humans and non-human animals, and conclude that many proposed design features of music and language follow naturally from their use in distinct dialogic and choric communicative contexts. Furthermore, the hybrid nature of intermediate systems like poetry, chant, or solo lament follows from their deployment in the less typical interactive context.

Acoustic correlates of the advanced vs. retracted tongue root feature in Igbo

Vowel harmony based on the advanced tongue root (±ATR) feature is a well-known attribute of the languages of the Macro-Sudan belt. Igbo (< Benue-Congo), one of these languages, on basis of which first instrumental studies of ±ATR articulation were conducted, has an asymmetric vowel system /i, ɪ, e, a, ɔ, o, ʊ, u/, so that root ±ATR harmony exists within three pairs and a single vowel /e/. This paper describes an acoustic realization of ±ATR in Igbo. According to the hypothesis that the value of the first formant in combination with the distribution of energy over the spectrum combine into a single perceptual cue that allows to distinguish vowels opposed by ±ATR we investigate (along with the description of the formant space) three spectral parameters that were shown to be acoustic correlates of ±ATR in other Macro-Sudan languages. The results of the instrumental analysis indicate that acoustic correlates of ±ATR harmony in Igbo are the value of the first formant, its bandwidth and normalized center of gravity. In addition, all parameters relevant for the ±ATR contrast in our data divided /ɔ/ utterances in different roots into two groups with contrasting values of the feature.

Chimpanzee vowel-like sounds and voice quality suggest formant space expansion through the hominoid lineage.

The origins of human speech are obscure; it is still unclear what aspects are unique to our species or shared with our evolutionary cousins, in part due to a lack of a common framework for comparison. We asked what chimpanzee and human vocal production acoustics have in common. We examined visible supra-laryngeal articulators of four major chimpanzee vocalizations (hoos, grunts, barks, screams) and their associated acoustic structures, using techniques from human phonetic and animal communication analysis. Data were collected from wild adult chimpanzees, Taï National Park, Ivory Coast. Both discriminant and principal component classification procedures revealed classification of call types. Discriminating acoustic features include voice quality and formant structure, mirroring phonetic features in human speech. Chimpanzee lip and jaw articulation variables also offered similar discrimination of call types. Formant maps distinguished call types with different vowel-like sounds. Comparing our results with published primate data, humans show less F1–F2 correlation and further expansion of the vowel space, particularly for [i] sounds. Unlike recent studies suggesting monkeys achieve human vowel space, we conclude from our results that supra-laryngeal articulatory capacities show moderate evolutionary change, with vowel space expansion continuing through hominoid evolution. Studies on more primate species will be required to substantiate this.This article is part of the theme issue ‘Voice modulation: from origin and mechanism to social impact (Part II)’.

Response patterns to vowel formant perturbations in children.

Auditory feedback is an important component of speech motor control, but its precise role in developing speech is less understood. The role of auditory feedback in development was probed by perturbing the speech of children 4-9 years old. The vowel sound /ɛ/ was shifted to /æ/ in real time and presented to participants as their own auditory feedback. Analyses of the resultant formant magnitude changes in the participants' speech indicated that children compensated and adapted by adjusting their formants to oppose the perturbation. Older and younger children responded to perturbation differently in F1 and F2. The compensatory change in F1 was greater for younger children, whereas the increase in F2 was greater for older children. Adaptation aftereffects were observed in both groups. Exploratory directional analyses in the two-dimensional formant space indicated that older children responded more directly and less variably to the perturbation than younger children, shifting their vowels back toward the vowel sound /ɛ/ to oppose the perturbation. Findings support the hypothesis that auditory feedback integration continues to develop between the ages of 4 and 9 years old such that the differences in the adaptive and compensatory responses arise between younger and older children despite receiving the same auditory feedback perturbation.

Vocal Tract Length Estimation Using Accumulated Means of Formants and Its Effects on Speaker-Normalization

Differences in vocal tract lengths (VTLs) in individual speakers cause variations in acoustic features of phonemes. In this paper, a simple method to estimate speaker-specific VTLs and to quantitatively evaluate some speaker-normalization effects of the VTLs is proposed. We employed accumulated means of formant trajectories to estimate the VTLs of speakers ranging from children to adults. For the formant estimation, the inverse-filter control (IFC) system was used. In the system, the decision of analysis order, which means number of formants to be estimated, is automated. Moreover, to evaluate the speaker-normalization effect of VTLs, we proposed the data reduction method, which can reasonably find dense areas of ellipses from distributions in the formant space. Using these ellipse areas, we evaluated the three normalization effects of VTLs: normalization by the mean of all VTLs as the standard, by speaker-categorical means of VTLs, and by individual VTLs. The area reduced from the standard area of the original data by 39.5% and 46.6% in the case of the categorical means and individual VTLs, respectively. As a result, our proposed method was used to provide a “normalized vowel map (NVM)” that visualizes universal vowel-distributions as a core image of linguistic information. Finally, we compared the estimated VTLs with those by another method based on magnetic resonance imaging (MRI) data, using the proposed methods.

Sensorimotor adaptation of speech depends on the direction of auditory feedback alteration.

A hallmark feature of speech motor control is its ability to learn to anticipate and compensate for persistent feedback alterations, a process referred to as sensorimotor adaptation. Because this process involves adjusting articulation to counter the perceived effects of altering acoustic feedback, there are a number of factors that affect it, including the complex relationship between acoustics and articulation and non-uniformities of speech perception. As a consequence, sensorimotor adaptation is hypothesised to vary as a function of the direction of the applied auditory feedback alteration in vowel formant space. This hypothesis was tested in two experiments where auditory feedback was altered in real time, shifting the frequency values of the first and second formants (F1 and F2) of participants' speech. Shifts were designed on a subject-by-subject basis and sensorimotor adaptation was quantified with respect to the direction of applied shift, normalised for individual speakers. Adaptation was indeed found to depend on the direction of the applied shift in vowel formant space, independent of shift magnitude. These findings have implications for models of sensorimotor adaptation of speech.

Vowel characterization of Spanish speakers from Antioquia–Colombia using a specific-parameterized discrete wavelet transform analysis

Vowel formants provide information as to how a vowel is uttered. Formant frequencies are relevant in applications involving human speech processing. However, such implementations are mainly performed with non-Spanish speakers. Thus, the Spanish vowels characterization should be further explored. In this study, a method for formants extraction based on the discrete wavelet transform is presented. The work focuses on Spanish speakers from Antioquia, Colombia. The parameters of the wavelet analysis are adjusted in order to establish a suitable vowels characterization within the frequency formant space. The results show that the vowel-specific wavelet analysis yields well defined clusters in the formant space. A k-means algorithm was trained in order to obtain representative centroids for each vowel. These centroids are tested in a vowels identification task, with good performance results. Moreover, the centroids are compared with vowel formants from Spanish speakers reported in the literature. The comparison reveals that speakers from distinct regions express specific features of vowels utterance, suggesting that speakers from regional populations within countries, can be better characterized. The proposed wavelet parametrization combined with the clustering algorithm can be attractive for real-time applications of voice processing. Furthermore, the proposed methodology can be applied in future studies with speakers from other Colombian- and Spanish-speaking regions.

Illusory Conjunctions in Speech Perception as a Lens into the Characteristics of Hearing Loss

This study explores the formation of a complex illusory conjunction in simulated speech perception that has yet to see a parallel in visual cognition. The illusory conjunction dealt with in this paper is confounded by 2 disparate spatial modalities – a) spatialization of competing formant features across high and low frequency bands on one hand and b) high-level expectation of speech content competing with the low level processing of auditory objects (such as speechmodulated noise). This paper has extended on a previous initial study around this topic, by controlling for the illusory conjunctions in one of the spatial dimensions (formant space) to then account for specific individual differences as possible correlations with individual hearing abilities across the audible frequency range. The results are an encouraging direction towards a better understanding of audition through the controlled perception of illusory conjunctions.

Examination of Clear Speech in Parkinson Disease Using Measures of Working Vowel Space

Purpose The purpose of the current study was to characterize clear speech production for speakers with and without Parkinson disease (PD) using several measures of working vowel space computed from frequently sampled formant trajectories. Method The 1st 2 formant frequencies were tracked for a reading passage that was produced using habitual and clear speaking styles by 15 speakers with PD and 15 healthy control speakers. Vowel space metrics were calculated from the distribution of frequently sampled formant frequency tracks, including vowel space hull area, articulatory-acoustic vowel space, and multiple vowel space density (VSD) measures based on different percentile contours of the formant density distribution. Results Both speaker groups exhibited significant increases in the articulatory-acoustic vowel space and VSD10, the area of the outermost (10th percentile) contour of the formant density distribution, from habitual to clear styles. These clarity-related vowel space increases were significantly smaller for speakers with PD than controls. Both groups also exhibited a significant increase in vowel space hull area; however, this metric was not sensitive to differences in the clear speech response between groups. Relative to healthy controls, speakers with PD exhibited a significantly smaller VSD90, the area of the most central (90th percentile), densely populated region of the formant space. Conclusions Using vowel space metrics calculated from formant traces of the reading passage, the current work suggests that speakers with PD do indeed reach the more peripheral regions of the vowel space during connected speech but spend a larger percentage of the time in more central regions of formant space than healthy speakers. Additionally, working vowel space metrics based on the distribution of formant data suggested that speakers with PD exhibited less of a clarity-related increase in formant space than controls, a trend that was not observed for perimeter-based measures of vowel space area.

Exploration of Metrics for Quantifying Formant Space: Implications for Clinical Assessment of Parkinson Disease

Purpose Speakers with Parkinson disease (PD) often exhibit hypokinetic dysarthria, which affects speech articulation. Vowel space metrics based on formant frequencies have been used to examine vowel articulation in speakers with PD. Although data from a number of studies suggest that speakers with PD exhibit smaller acoustic vowel space areas than control speakers, a handful of studies did not observe differences in vowel space area between speakers with and without PD. One potential factor explaining the inconsistent performance of traditional vowel space metrics is that these point-based metrics undersample the formant space to adequately capture between-groups and within-group differences in articulation. This article discusses recent advances in vowel space assessment that augment traditional vowel space metrics by examining the distribution of the entire formant frequency trace. Conclusion A general approach to obtaining these metrics is discussed along with clinical implications for vowel space assessment in speakers with PD.