A study comparing the duration of assibilant, affricate, singleton, geminate and syllabic /s/ from the citation speech of one speaker demonstrated significant differences in the duration of geminate /s/ (µ = 300 ms), syllabic /s/ (µ = 240 ms), singleton /s/ (µ = 155 ms), and affricate /s/ (µ = 130 ms). The results show the expected contrast between short and long /s/, and between inter-consonantal long /s/ and affricate /s/, lending support to the Blackfoot syllabic /s/ analysis in Derrick (2006). Length measurements also showed a significant symmetrical relationship between vowel adjacency and long /s/ duration, demonstrating an inverse relationship between amplitude and duration of Blackfoot /s/. The cross linguistic implications for sibilants are significant and further research with more participants, more languages and using natural speech, into the relationship between duration and intensity is indicated.