![]() ![]() These stops are followed by high (close), mid, or low (open) vowels, and the verbs are produced after a word ending in either the vowel or the nasal in four syntactically and semantically appropriate contexts. To empirically support his hypothesis, Kingston (2008) analyzed Spanish voiced and voiceless stops /b, d, ɡ, p, t, k/ produced as consonant onsets of verbs by two female speakers–one from Peru and the other from Ecuador. That is, in Kingston's view, lenition complements fortition and is governed by the position of the affected segment within a prosodic constituent: with greater intensity and less signal disruption, lenition signals continuation within prosodic constituent while fortition decreases signal intensity and increases signal disruption at the edges of prosodic constituents. ![]() He hypothesizes that lenition is governed “not by how far articulators have to travel but instead by the difference in intensity the speaker wishes to create between the affected segment and its neighbors” ( Kingston, 2008). On the other hand, Kingston (2008) argued that the purpose of lenition is to reduce the interruption of the stream of speech to convey that the affected consonant resides within a prosodic constituent. Consistent with the articulatory effort-based approach, Kirchner (1998, 2013) proposed that lenition is driven by the grammatical constraint, called LAZY, in Optimality Theoretic account, which stipulates that pronunciation of any given sound should be exerted by as little effort as possible. However, these approaches generally agree that lenition processes and outputs are found in similar environments across languages (e.g., in intervocalic, word-medial positions and in unstressed syllables), and that relative changes in duration and intensity, and degrees of oral constriction of the affected consonants are observed ( Broś et al., 2021).ĭisagreement remains, however, on the ultimate motivation of the lenition process. For instance, the articulatory-based account can unify processes that involve a loosening of articulatory stricture, such as spirantisation, vocalisation, and debuccalisation however, it excludes obstruent voicing because voicing increases impedance to airflow which has the opposite aerodynamic effects of increasing the degree of articulatory aperture ( Harris et al., 2023). These many definitions differ, amongst other things, in their abilities to provide a unifying definition of the phonetic effect that lenition has on consonants. Finally, lenition has been defined as the extent to which a consonant modulates the carrier signal ( Harris et al., 2023). Furthermore, decreasing resistance to airflow in the oral tract has been taken as the defining acoustic characteristic of lenition (e.g., Kingston, 2008 Lavoie, 2001). Another definition views lenition as an increase in sonority which has been widely interpreted as an increase in intensity (e.g., Lavoie, 2001). Lenition can be defined as a decrease in the amount of articulatory effort, ease, or undershoot (e.g., Bauer, 2008 Kirchner, 1998, 2013). Phonetically, many definitions of lenition have been proposed. ![]() Bauer (2008) raised two objections against this historical–phonological definition of lenition, namely, its exclusion of any change to be called lenition until its final zero stage and its assumption that the progression towards zero is monotonic. Phonologically, “A segment X is said to be weaker than a segment Y if Y goes through an X stage on its way to zero” ( Hyman, 1975). Known factors affecting degrees of lenition of Spanish stops including preceding segments, following vowel height, voicing, and place of articulation of the target stop phonemes were tested to assess the validity of the approach. In addition to being sensitive to language-specific acoustic parameters that are contrastive for the two phonological features, it is semi-automatic. Specifically, our approach projects gradient surface acoustic parameters onto two phonological features that capture the possible categorical manifestation of Spanish stop lenition from stop (-continuant, -sonorant) to fricative (+continuant, -approximant) or to approximant (+continuant, +sonorant). Unlike previous approaches where values along different acoustic dimensions are directly used to estimate lenition, in this approach, degrees of lenition were estimated from the posterior probabilities of sonorant and continuant phonological features computed directly from the speech signals by bidirectional recurrent neural networks (RNNs). The goal of this study is to evaluate a new approach to quantify degrees of lenition. ![]()
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