Voicing and voice assimilation in Russian stops

The main objective of this thesis is to investigate acoustic cues for the voicing contrast in stops in Russian for effects of speaking rate and phonetic environment. Although the laryngeal contrast in Russian is assumed to be a [voice] contrast, very few experimental studies have looked at the acoustic properties of Russian voiced and voiceless stops. Most claims about acoustic properties of stops and phonological processes that affect them (voice assimilation and final devoicing) have been made based on impressionistic transcriptions. The present study provides evidence that (1) voicing in voiced stops is affected by speaking rate manipulation, (2) stops in Russian retain underlying voicing contrast in presonorant position and voice assimilation occurs only in obstruent clusters, and (3) phonological processes of voice assimilation and final devoicing do not result in complete neutralization.

The target of the investigation is voiced and voiceless intervocalic stops, stops in clusters, and final stops in different prosodic positions within a word and at the phrase level. The acoustic cues to voicing (duration of voicing, stop closure duration, vowel duration, f0, and F1) were measured from the production data of 14 monolingual speakers of Russian recorded in Russia. Speakers produced words and phrases with target stops in three speaking rate conditions: list reading, slow rate and fast rate. The data were analyzed in 5 blocks focusing on (1) word-internal stops, (2) voice assimilation in stops in prepositions, (3) cases of so-called "sonorant transparency", (4) voice assimilation in stops before /v/, and (5) voicing processes across a word boundary.

The results of the study present a challenge to the widely-held assumption that phonological processes precede phonetic processes at the phonology-phonetics interface. It is shown that the underlying contrast leaves traces on assimilated and devoiced stops. To account for the findings, a phonology-phonetics interface that allows interaction between the modules is required. In addition, the results show that temporal cues are affected by speaking rate manipulation, but the effect of rate on voicing is found only in voiced stops. Duration of voicing and VOT in voiceless stops are not affected by speaking rate. The results also show that no effect of C2 is obtained on voicing in C1 stops in in obstruent-sonorant-obstruent clusters, thus no "phonological sonorant transparency to voice assimilation" is found in Russian. Rather, the study provides evidence that there is variation in production of voicing in stops in prepositions, and that voice assimilation in stops before /v/ followed by a voiced obstruent is optional for some speakers.