Evidence has been accumulating that speakers adjust their speech production to account for conditions of signal transmission to an interlocutor, in addition to speaker- and listener-related influences. This study manipulated acoustic transmission conditions between speakers and a researcher while they completed dyadic cooperative puzzle tasks. Speakers heard evidence of four transmission perturbations (intensity increase/decrease, pitch increase/decrease) only indirectly, i.e., via changes in the researcher's voice. Analysis of speakers' conversational turns across conditions (baseline + four partner-voice manipulations) showed significant group-level imitation of transmission manipulations of partner voice intensity, with no general response to shifts in partner voice pitch. Significant voice alterations were also observed for individual speakers in intensity, with substantial inter-talker variability in responses. Thirteen of 29 speakers exclusively imitated the manipulation of partner intensity, 4/29 speakers exclusively opposed the transmission manipulation, and 4/29 speakers showed both response types. The presence of opposition responses coupled with a relatively low-magnitude group-level convergence suggests the possibility of a compensatory force at work in at least some speakers, adjusting for changes made during signal transmission despite their lack of direct experience with the transmission manipulation effects.