There is a system of English mouthing during interpretation that appears to be the result of language contact between spoken language and signed language. English mouthing is a voiceless visual representation of words on a signer's lips produced concurrently with manual signs. It is a type of borrowing prevalent among English-dominant bilingual-bimodal sign language interpreters who use American Sign Language (ASL) and spoken English when interpreting for deaf consumers (Davis, 1989; Weisenberg, 2003). It is distinct from other systems of grammatical mouthing observed in native deaf signers. Bilingual-bimodal interpreters have the advantage of simultaneity : the two channels of expression are distinctly different: one, a visual-gestural channel, the other, oral-aural. When sign language interpreters organize abstract oral English discourse into a concrete visual-spatial form, they borrow from their dominant language, English. This study tested audience effects during interpretation from spoken English to ASL. Interpreters shifted their style to accommodate their addressees. A style shift was measured by the rate of English mouthing. Based on an analysis of variance (ANOVA) F(1,3) = 6.25, p = 0.08, the study demonstrates that the perceived cultural identity of the audience has more of an effect on English mouthing than topic, F(1, 3) = 0.046, p = 0.84. A pattern of mouthing reduction was also discovered. At least two experimental contexts contained technical terminology that was repeated. When there were no manual equivalents in ASL, interpreters interpreted these terms by overlapping mouthing with a manual sign of approximate meaning. Once they had expressed the combination, the mouthing was reduced or removed completely. This study confirms what is a commonly held notion in audience design, that speakers adjust their language in reaction to their addressees, and also opens up an inquiry to the use of the sign language interpreting context as a means of examining neologisms and language variability. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]