It has generally been accepted that vowels are shorter before voiceless consonants than before voiced consonants in English. The purpose of this study was to investigate duration and intensity of English word-final alveolar fricatives with preceding vowels depending on gender, age, function word versus content word, word frequency, and preceding vowel length of alveolar fricatives factors based on the Buckeye Corpus of Conversational Speech. First, vowel shortening before voiceless alveolar fricatives was not found. Overall preceding vowel durations of the voiceless and voiced alveolar fricatives were longer than frication noise durations. Second, the ratio of preceding vowel duration to frication noise duration appeared to be larger in voiced contexts than in voiceless contexts. Third, there was no significant gender difference in the ratio of preceding vowel duration to frication noise. These results suggest that preceding vowel durations are not determined by the voicing of alveolar fricatives and that vowel shortening before voiceless alveolar fricatives does not apply in a conversational speech.