Date Published: March 11, 2019
Publisher: Public Library of Science
Author(s): Susana Rodrigues, Fernando Martins, Susana Silva, Luis M. T. Jesus, Sara Finley.
In this paper, we present a production study to explore the controversial question about /l/ velarisation. Measurements of first (F1), second (F2) and third (F3) formant frequencies and the slope of F2 were analysed to clarify the /l/ velarisation behaviour in European Portuguese (EP). The acoustic data were collected from ten EP speakers, producing trisyllabic words with paroxytone stress pattern, with the liquid consonant at the middle of the word in onset, complex onset and coda positions. Results suggested that /l/ is produced on a continuum in EP. The consistently low F2 indicates that /l/ is velarised in all syllable positions, but variation especially in F1 and F3 revealed that /l/ could be “more velarised” or “less velarised” dependent on syllable positions and vowel contexts. These findings suggest that it is important to consider different acoustic measures to better understand /l/ velarisation in EP.
The alveolar lateral approximant has been attracting growing attention in speech research. One reason to this is that phonetic manifestations of the lateral approximant /l/ are characterised by considerable variability across and within languages and dialects, which results in contradictory positions about /l/ velarisation in the literature. In European Portuguese (EP), the lateral is traditionally associated with non-velarised (light) /l/ in syllable onset and velarised (dark) /l/ in coda position (categorical view), but more recent acoustic and articulatory studies considered the existence of velarised realisations of /l/ in both onset and coda positions [1–8]. The present study is concerned with /l/ velarisation in EP and reports acoustic data of /l/ in different vowel contexts and syllable positions. To lay the groundwork for the discussion, several acoustic measures and a variety of linguistic contexts that have not been considered in EP before, are now explored. What is the influence of the syllable position on the acoustic properties of the realisations of /l/? What is the effect of the vowel context on the acoustic properties of the realisations of /l/? Which acoustic properties could be considered to clarify the /l/ velarisation behaviours in EP? The present study explicitly addresses these questions.
An independent ethics committee (Comissão de Ética da UICISA-E, Coimbra, Portugal) gave specific approval for this study. All speakers agreed to participate in the study and gave their written informed consent.
The present study of /l/ production in different syllable positions (onset, complex onset and coda) and in different vowel contexts ([i, e, ε, a, u, o, ɔ]) tested the validity of the continuum hypothesis in which the velarised /l/ shows gradual, non-categorical phonetic properties. We predicted a main effect of syllable position in all vowel contexts and a main effect of vowel context in all syllable positions. It was also predicted that syllable position would interact with vowel context, as observed in at least for some acoustic measures.
The study presented here provides novel contributions to the acoustic description of EP /l/, using new acoustic measures (such as F3 and the slope of the F2 transition) to describe /l/ velarisation. In most cases, velarisation is not correlated with a single formant but is specified by the joint contribution of the different acoustic measures. It is clear from the results obtained, that it is important to consider acoustic measures such as F1, F2, F3 and the slope of the F2 transition to better understand /l/ velarisation.