In Central Catalan, word-final sibilants and stop + sibilant clusters undergo voicing when followed by a vowel in the next word. In word-final pre-vocalic singleton stops, however, no voicing is observed. This asymmetry is unexpected from the point of view of phonetic naturalness, and it invites a closer empirical investigation, especially in the light of recent phonetic findings which challenge earlier descriptions of a similar voicing process before sonorant consonants in Catalan. This study presents a systematic acoustic comparison of voicing in pre-vocalic stops /p, b/, sibilants /s, z/ and stop + sibilant clusters /bz/ with voicing before obstruents and before sonorant consonants. The results show that while pre-sonorant voicing is limited and highly variable, pre-vocalic sibilant and cluster voicing are both robust categorical processes for most speakers. Drawing on evidence from how voicing is realised in a subset of gradient cases, I propose that pre-vocalic cluster voicing developed from pre-vocalic sibilant voicing which in turn descended from an earlier intervocalic voicing process. I further question whether the outcome of the sound changes in Catalan can be synchronically analysed using grounded markedness constraints, and to what extent the pre-vocalic voicing may be regulated by universal vs. language-specific mechanisms of phonological abstraction.