1 The consonant length contrast in Persian: Production and perception Benjamin B. Hansen & Scott Myers Department of Linguistics, University of Texas at Austin Abstract In Persian, length contrasts occur in all classes of consonants, including obstruents, glides and laryngeals. The results of an acoustic study of Persian consonant length are reported, showing that geminates differ from singletons across speaking rates and manner classes in constriction duration, preceding vowel duration, formant transition duration, and the intensity drop from the preceding vowel. Two perception studies tested the claim that consonant length contrasts are more difficult for Persian speakers to perceive when the consonant is more similar to neighboring vowels, as is the case with glides and laryngeals. In one of these experiments, Persian speakers identified the length class of consonants differing in constriction duration and consonant type. Identification was most consistent and rapid when the test consonant was an obstruent, and least so when it was laryngeal. In the other perception experiment, subjects identified the length class in consonants differing in both constriction duration and formant transition duration. Consonants with longer formant transitions were more likely to be identified as long than consonants with shorter transitions, but also were identified less consistently and more slowly. These results suggest a phonetic explanation for the avoidance of length contrasts in more vowel-like consonants in many languages.