--- id: walczak26_interspeech title: "From onset to coda: spectral variation in normative Polish /s/ produced by children" authors: - Joanna Walczak - Oliwia Skórzewska - Zuzanna Miodońska year: 2026 doi: 10.21437/Interspeech.2026-1936 isca_url: https://www.isca-archive.org/interspeech_2026/walczak26_interspeech.html pdf_url: https://www.isca-archive.org/interspeech_2026/walczak26_interspeech.pdf session: Speaker-Specific, Forensic and Segmental Characteristics of Typical and Atypical Speech topics: - phonetics - prosody - dataset category: phonetics-linguistics institutions: - Silesian University of Technology funding: - National Science Centre, Poland - European Funds for Silesia - Just Transition Fund code: url: "" license: "" open_to_collaboration: false wiki_frontmatter: id: walczak26_interspeech category: phonetics-linguistics institutions: - Silesian University of Technology updated: 2026-09-29 confidence: full-paper digest: v2 source: https://doi.org/10.21437/Interspeech.2026-1936 pdf: https://www.isca-archive.org/interspeech_2026/walczak26_interspeech.pdf wiki_url: https://interspeech-2026-wiki.vercel.app/papers/walczak26_interspeech/ markdown_url: https://interspeech-2026-wiki.vercel.app/papers/walczak26_interspeech/markdown.md --- # From onset to coda: spectral variation in normative Polish /s/ produced by children *Joanna Walczak, Oliwia Skórzewska, Zuzanna Miodońska* [PDF](https://www.isca-archive.org/interspeech_2026/walczak26_interspeech.pdf) · [ISCA page](https://www.isca-archive.org/interspeech_2026/walczak26_interspeech.html) · [DOI](https://doi.org/10.21437/Interspeech.2026-1936) **Category:** `phonetics-linguistics` **TL;DR** — This pilot study investigates word-position effects on the spectral properties of perceptually normative Polish /s/ produced by 102 preschool children, finding significant positional variations driven primarily by initial-medial contrasts across spectral centroid, flux, kurtosis, and skewness. ## Key contributions - Quantified word-position acoustic variation (initial, medial, final) on 816 tokens of normative Polish /s/ from 5-8 year old children. - Demonstrated that word-initial /s/ exhibits significantly lower spectral centroid, flux, and kurtosis compared to word-medial /s/ (Cohen's d up to 1.09). - Revealed that medial-final contrasts are largely non-significant except for spectral skewness, positioning word-final /s/ as intermediate. - Employed linear mixed-effects (LME) models controlling for stress, preceding/following phones, and parent word as random effects. ## Problem Sibilant fricatives like Polish /s/ are shaped by linguistic and developmental factors, yet word-position effects remain underdescribed in children's speech. Prior approaches often overlook how prosodic organization, boundary-related timing, and coarticulatory demands alter spectral properties even in perceptually normative productions. This gap makes it difficult to fully understand child speech motor development and establish language-specific acoustic baselines. ## Method The corpus consists of 816 tokens from 102 Polish-speaking children aged 5-8 years pronouncing 8 basic vocabulary words containing /s/ in initial, medial, and final positions. Audio was recorded via Panasonic WM61 electret microphones at 15 cm distance, sampled at 44.1 kHz with 16-bit resolution. Signals were manually segmented using 20 ms Hamming windows with a 10 ms overlap and 50 Hz spectral resolution STFT. Five acoustic features were extracted per frame and averaged per token: first spectral moment / spectral centroid (CoG), spectral kurtosis (M4), spectral skewness (M3), and spectral flux. Linear mixed-effects (LME) models were fitted with word position as a fixed effect (initial as intercept), by-speaker random intercepts and slopes for stress, preceding phone, and following phone, and a random intercept for parent word. Pairwise contrasts were evaluated using estimated marginal means (EMMs) with Bonferroni adjustments. ## Experimental setup The dataset comprised 816 /s/ tokens from 102 preschoolers from the PAVSig database, spanning 8 words. Statistical analyses were performed in R 4.4.2 using lme4, with signal processing in Matlab 2023b. Metrics included estimated marginal means of CoG, flux, kurtosis, and skewness, evaluated via Bonferroni-adjusted pairwise contrasts and Cohen's d effect sizes. ## Results The initial-medial contrast yielded the largest effect sizes across all measures (d = 0.65-1.09, p < 0.001), with word-initial /s/ showing lower CoG, flux, and kurtosis than medial tokens. Initial-final differences were also significant (d = 0.47-0.56, p < 0.001), while medial-final differences were non-significant except for spectral skewness (d = 0.53, p = 0.02). | Acoustic Feature | Initial vs Medial (d) | Initial vs Medial (p) | Initial vs Final (d) | Initial vs Final (p) | Medial vs Final (d) | Medial vs Final (p) | | --- | --- | --- | --- | --- | --- | --- | | Spectral Centroid | 0.82 | < 0.001 | 0.47 | 0.01 | 0.36 | 0.22 | | Spectral Flux | 0.65 | < 0.001 | 0.48 | < 0.001 | 0.17 | 0.84 | | Spectral Kurtosis | 0.75 | < 0.001 | 0.47 | < 0.001 | 0.27 | 0.27 | | Spectral Skewness | 1.09 | < 0.001 | 0.56 | < 0.001 | 0.53 | 0.02 | ## Limitations The study relies on a small, unbalanced lexical corpus of only 8 words, limiting generalizability. Age was treated merely as a sample descriptor rather than modeled as a covariate, and no adult control group was included for baseline comparison. ## Why read this Phoneticians and speech researchers studying child language acquisition will learn how word boundary contexts systematically bias spectral moments of sibilants even in perceptually correct speech. ## Code None released (as of this page's `updated` date). If you are an author with a repo, please claim this entry — see CONTRIBUTING.md. ## Applications Speech-language pathology assessment tools, children's speech recognition systems, and developmental phonetics research. ## Institutions / 機構 Silesian University of Technology **Funding / 經費:** National Science Centre, Poland, European Funds for Silesia, Just Transition Fund ## Related - [Age-dependent acoustic changes of the frication noise in dental sibilants produced by typically developing Polish children between 5 and 8 years of age](miodonska26_interspeech.md) — same problem · relatedness 2.1/3 - [Detection of Incorrect Place of Articulation in Polish Sibilants Using Convolutional Autoencoders](pieniazek26_interspeech.md) — complementary · relatedness 2.0/3 - [Informativity of high-frequency bands on the place of articulation shift in retroflex sibilants produced by children](skorzewska26_interspeech.md) — same problem · relatedness 1.9/3 - [Sorting Clusters into the Shape of the Word: Positional Distribution of Probabilities](chuprina26_interspeech.md) — same problem · relatedness 1.9/3 - [Phoneme-Level Mispronunciation Screening in Polish-Speaking Children with an Explainable Assistant](dudek26_interspeech.md) — complementary · relatedness 1.9/3 All 950k paper pairs scored by TypeSafe Jev (`scripts/related/`); relatedness 0 = unrelated … 3 = directly comparable.