While there are many phonological analyses of voicing assimilation in Slavic languages (Rubach 1996,
1997, 2008; Butska 1998; Lombardi 1999; Wetzels & Mascaró 2001, Vignjević 2004, to name but a few), there has been considerably less attention paid to the phonetic details of this process (Hayes 1984;
Burton & Roblee 1999; Kulikov 2010, 2012). Phonetic analyses of the voicing contrast, in general, however, are not as rare, though they focus mainly on Russian (Hayes 1984; Kulikov 2012; Kharlamov
2012; 2014; Ringen & Kulikov 2014), Polish (Keating 1983; Jassem & Richter 1987), and, of special importance to this study, Serbian (Sokolović-Perović 2012).
Works on Serbo-Croatian, including phonological and phonetic studies and grammars, agree that there is a contrast of voice (as in other Slavic languages) in all positions, including word-finally
(unlike most other Slavic languages). Assimilation in Serbo-Croatian is represented orthgraphically, except for <d+s> and <d+š> at morpheme boundaries. Grammars, however, do not agree on the phonetic facts about these clusters. This deviation in spelling is either not mentioned (Partridge 1964), unclearly described (Grozdić 1969; Grubišić 2007), or said to be an orthographic irregularity, with the phonetic realization being [ts] and [tʃ] (Hammond 2005). However, Vignjević (2004), in a phonological analysis, mentions that there is a failure to devoice, leading to phonetic [ds] and [dʃ]. This disagreement, as well as anecdotal evidence from native speakers of a Bosnian variety about /b+s/ clusters, raises question of what the phonetic facts of voicing assimilation in this language are. This study attempts to determine the assimilatory facts of Bosnian for clusters at morpheme boundaries and morpheme-
internally.
Two types of clusters were investigated: those created by the addition of a suffix (i.e., rob ‘slave’
+ -stvo ‘-hood’) and those that involve a fleeting-vowel where clusters occur morpheme-internally (i.e.,
sladak ‘sweet (masc.)’ + -a (fem.) = sladØka ‘sweet (fem).’). Four speakers of Bosnian living in the United
States completed a word-list task involving alternations of a singleton, underlyingly-voiced stop (only /b/ and /d/ were studied) with the same stop in assimilation contexts (before voiceless obstruents /s/, /k/,
/ʦ/, and /ʧ/). In both types of alternation, an underlyingly voiced stop not in a cluster is compared to the
same stop in a cluster where voicing assimilation could be expected. Voicing ratio in the underlyingly voiced stop was calculated in both non-assimilatory (to ensure that they were, in fact, voiced) and assimilatory (to determine to what extent, if any, they devoice) contexts.
While there were differences in voicing between two morphological environments, overall, voicing during closure of the initial segment of a cluster was not indicative of phonologically voiceless stops. The results show that more voicing and more variation in assimilatory contexts than would be expected for phonological assimilation, as found in Russian (Kulikov 2012). What devoicing does occur appears to be phonetic in nature.