Objective: To determine the effects of room reverberation on target sentence recognition in the presence of 0-to-3 synchronous masking sentences. Design: Target and masker sentences were presented through four loudspeakers (± 90° and ± 45° azimuth; 1m from the listener) in rooms having reverberation times (RT) of 0.2, 0.4, 0.6, and 1.1 s. Study Sample: Four groups of 13 listeners each participated in the study (N = 52).RESULTS: In rooms with RTs of 0.2, 0.4, and 0.6 s, mean speech recognition scores (SRSs) were similar, with scores ranging from 96-100%, 90-95%, 75-80%, and 53-60%, when 0, 1, 2, and 3 competing sentences were present, respectively. However, in the room with a RT = 1.1 s, SRSs deteriorated significantly faster as the number of competing sentences increased; mean scores were 93%, 73%, 26%, and 10%, in the 0, 1, 2, 3, competing sentence condition, respectively. The majority of errors in SRSs (98%) resulted from listeners reporting words presented in masking sentences along with those in target sentences (mixing errors). Conclusions: Results indicate that reverberation has a similar influence on SRSs measured in multi-talker environments, when room reverberation is ≤ 0.6 s. However, SRSs are dramatically reduced in the room with a RT = 1.1 s, even when only one competing talker is present. (PsycINFO Database Record (c) 2016 APA, all rights reserved)