The temporal structure of speech is altered dramatically when a person uses sign language and speaks aloud simultaneously (i.e., simultaneous communication or SC). Notable among these temporal alterations are durational increases of vowels, pause times between words, and voice onset times. Temporal aspects of speech play a pivotal role in the perception of certain phonemic contrasts in spoken English. For example, cues for the perception of final consonant voicing are carried in the vowel that precedes the final consonant. The purpose of the present study was to investigate the effect of increased segment durations associated with speech produced during SC on final consonant voicing perception. Eight skilled SC users produced naturally spoken words that differed only in the voicing characteristic of the final consonant. The words were recorded under two conditions: (a) speech alone and (b) SC. Digital editing was used to remove the final consonant. The digitally altered words were played to 20 listeners who, in a forced-choice paradigm, circled the word they thought they heard. The listeners accurately identified final consonant voicing of 69.2% of the target words produced in the speech alone condition and 77.0% of the target words in the SC condition, a nonsignificant difference.