The present work was undertaken in order to provide further evidence about the role played by the physiological and phonological factors in vowel lengthening before voiced consonants. Previous experiments compared cross‐linguistically different consonantal contexts and syllabic types, but, with respect to Spanish disregarded neutralization in final syllable position. Two male adults recorded nonsense bisyllabic words and two other speakers recorded meaningful frequent words where the opposition voiced/voiceless was spontaneously neutralized. Results showed that in open and closed syllables of nonsense utterances (average ratios: 1.4 and 1.23, respectively) vowels are shorter before voiceless consonants than before voiced. In meaningful words, vowels presented longer duration before voiced realizations (20%) of lengthening. However, for nonsense utterances, higher values were obtained and we can assume that this difference is indicating some phonological effect. The lengthening value observed in meaningful words seems to represent more closely the physiological effect.