Articulatory characterization of the alveolar sibilant fricatives of Basque: Part one

An articulatory analysis of the two alveolar sibilant fricatives of Basque (<z> and <s>) is presented, based on fifteen collections of 2D and 3D magnetic resonance images. By applying a set of phonetic, qualitative and quantitative parameters, two articulatory models for <z> and three for <s> are identified, and the procedures used to distinguish between them are examined. The main models are: dorsal denti-alveolar for <z> and apico-alveolar for <s>. Due to its length, the work is presented in two separate parts.

Spectral properties of anterior sibilant fricatives in Northern Peninsular Spanish and sibilant-merging and non-merging varieties of Basque

This paper focuses on the spectral properties of anterior sibilant fricatives in Northern Peninsular Spanish, and sibilant-merging and non-merging varieties of Basque. Non-merging varieties of Basque have two voiceless anterior sibilant fricatives, characterized as apico-alveolar and lamino-alveolar. In other Basque varieties, however, these two phonemes have merged with varying results. Twenty-four participants divided into four different groups have been studied. One group is a set of monolingual Spanish speakers from north-central Spain, while the remaining three are Basque–Spanish bilingual groups with different sibilant fricative systems in Basque. The goal is to describe the spectral properties of anterior sibilant fricatives and examine the effect of the L1-Basque sibilant system upon L2-Spanish. The Basque varieties chosen are: (i) Azpeitia Basque, where merging in favor of the lamino-alveolar sibilant fricative has occurred; (ii) Lemoa Basque, where the merging in favor of the apico-alveolar sibilant fricative is widespread; and (iii) Goizueta Basque, where no merging has happened. Participants took part in an elicitation task where they produced sentences containing target words with an intervocalic anterior sibilant fricative in Basque and Spanish. Bayesian probability was used for inferential statistics. Speakers of the non-merging Basque variety show the narrowest acoustic dispersion of /s/ in Spanish, as opposed to broader diffusion in the other three groups. Regarding L1 transfer, while the Azpeitia group does not show transfer into Spanish, the Lemoa and Goizueta groups do. Results show that /s/ is more fronted for monolingual Spanish speakers from north-central Spain than the previous literature has reported.

Italian preconsonantal s-voicing is not regressive voice assimilation

In the literature of laryngeal phonology Romance languages are considered voice languages, exhibiting a binary distinction between a voiced lenis and a voiceless fortis set of obstruents. Voice languages are characterised by regressive voice assimilation (RVA) due to the phonological activity of [voice]. Italian manifests a process similar to RVA, called preconsonantal s-voicing; that is, /s/ becomes voiced before voiced consonants. Since /sC/ is the only obstruent cluster in Italian phonotactics, Italian seems to fulfil the requirements for being a prototypical voice language. However, this paper argues that s-voicing is not an instance of RVA, at least from a synchronic phonological point of view. RVA and Italian preconsonantal s-voicing essentially differ at every level of a synchronic comparison: in the input, in the trigger, in the domain of application and in the frequency of the processes. In Italian only sibilant fricatives may undergo voicing before consonants; however, other obstruents (which mostly appear in loanwords) do not assimilate for [voice]. Italian preconsonantal s-voicing does not take place at the word boundary or at morpheme boundaries, and it seems to be optional is new loanwords; thus, it is not a postlexical process like RVA. The synchronic differences between the two phenomena are analysed in Classical Optimality Theory. The laryngeal system of Italian prefers faithfulness over markedness, which means that non-/sC/ obstruent clusters surface with underlying voice values; while the voicing of /s/ before voiced consonants is seen as phonetic and not phonological.

Spit or sbit? ST-type consonant clusters in the speech of Polish learners of English

This paper presents two small-scale acoustic phonetic studies investigating the pronunciation of sibilant-stop (ST) consonant clusters in Polish, and in the L2 speech of L1 Polish learners of English. In English, aspiration of fortis stops is not attested in the post-/s/ context. Rather, short-lag voice onset time (VOT) measures are observed in L1 English in post-/s/ stop consonants, a phonetic weakening that renders them phonetically similar in terms of VOT to lenis stops in initial position. In Polish, both voiced and voiceless stops may appear after sibilant fricatives. The acoustic results suggest that (1) L1 Polish does not weaken its stops in ST clusters, and (2) that more L1 Polish speakers exhibit some weakening in their L2 English clusters as a function of proficiency, but do not produce native-like VOTs in ST sequences. Implications of these findings for L2 speech research and the phonological status of ST clusters are discussed.

Sibilant Fricative Merging in Taiwan Mandarin: An Investigation of Tongue Postures using Ultrasound Imaging

In Taiwan Mandarin, retroflex [ʂ] is allegedly merging with dental [s], reducing the traditional three-way contrast between sibilant fricatives (i.e., dental [s]–retroflex [ʂ]–alveopalatal [ɕ]) to a two-way contrast. Most of the literature on the observed merging focuses on the acoustic properties and perceptual identification of the sibilants, whereas much less attention has been drawn to the articulatory evidence accounting for the aforementioned sibilant merging. The current study employed ultrasound imaging techniques to uncover the tongue postures for the three sibilant fricatives [s, ʂ, ɕ] in Taiwan Mandarin occurring before vowels [a], [ɨ], and [o]. Results revealed varying classes of the [s–ʂ] merger: complete merging ( overlap), no merging ( non-overlap), and context-dependent merging ( context-dependent overlap, which only occurred before [a]). The observed [s–ʂ] merger was also confirmed by the perceptual identification by trained phoneticians. Center of gravity (CoG), a reliable spectral moment of identifying different sibilant fricatives, was also measured to reflect the articulatory–acoustic correspondence. Results showed that the [s–ʂ] merger varies across speakers and may also be conditioned by vowel contexts and that articulatory mergers may not be entirely reflected in CoG values, suggesting that auxiliary articulatory gestures may be employed to maintain the acoustic contrast.

Acoustic–phonetic and auditory mechanisms of adaptation in the perception of sibilant fricatives

Listeners are highly proficient at adapting to contextual variation when perceiving speech. In the present study, we examined the effects of brief speech and nonspeech contexts on the perception of sibilant fricatives. We explored three theoretically motivated accounts of contextual adaptation, based on phonetic cue calibration, phonetic covariation, and auditory contrast. Under the cue calibration account, listeners adapt by estimating a talker-specific average for each phonetic cue or dimension; under the cue covariation account, listeners adapt by exploiting consistencies in how the realization of speech sounds varies across talkers; under the auditory contrast account, adaptation results from (partial) masking of spectral components that are shared by adjacent stimuli. The spectral center of gravity, a phonetic cue to fricative identity, was manipulated for several types of context sound: /z/-initial syllables, /v/-initial syllables, and white noise matched in long-term average spectrum (LTAS) to the /z/-initial stimuli. Listeners’ perception of the /s/–/ʃ/ contrast was significantly influenced by /z/-initial syllables and LTAS-matched white noise stimuli, but not by /v/-initial syllables. No significant difference in adaptation was observed between exposure to /z/-initial syllables and matched white noise stimuli, and speech did not have a considerable advantage over noise when the two were presented consecutively within a context. The pattern of findings is most consistent with the auditory contrast account of short-term perceptual adaptation. The cue covariation account makes accurate predictions for speech contexts, but not for nonspeech contexts or for the absence of a speech-versus-nonspeech difference.

Acoustic-phonetic and auditory mechanisms of adaptation in the perception of sibilant fricatives

Listeners are highly proficient at adapting to contextual variation when perceiving speech. The present study examined the effects of brief speech and non-speech contexts on the perception of sibilant fricatives. We explored three theoretically motivated accounts of contextual adaptation based on phonetic cue calibration, phonetic covariation, and auditory contrast. Under the cue calibration account, listeners adapt by estimating a talker-specific average for each phonetic cue or dimension; under the cue covariation account, listeners adapt by exploiting consistencies in how the realization of speech sounds vary across talkers; under the auditory contrast account, adaptation results from (partial) masking of spectral components that are shared by adjacent stimuli. The spectral center of gravity, a phonetic cue to fricative identity, was manipulated for several types of context sound: /z/-initial syllables, /v/-initial syllables, and white noise matched in long-term average spectrum (LTAS) to the /z/-initial stimuli. Listeners’ perception of the /s/–/ʃ/ contrast was significantly influenced by /z/-initial syllables and LTAS-matched white noise stimuli, but not by /v/-initial syllables. No significant difference in adaptation was observed between exposure to /z/-initial syllables and matched white noise stimuli, and speech did not have a considerable advantage over noise when the two were presented consecutively within a context. The pattern of findings is most consistent with the auditory contrast account of short-term perceptual adaptation. The cue covariation account makes accurate predictions for speech contexts, but not for non-speech contexts or the absence of a speech vs. non-speech difference.