This paper describes a perception experiment with L1 Polish and L1 English listeners on the affrication of initial English /tr/ and /dr/ (TR) consonant clusters. The goal was to test phonological predictions formulated within the Onset Prominence (OP) framework. OP offers two distinct structural configurations for representing rising sonority onset clusters. One predicts synchronous cluster articulation in English, giving rise to affrication, while the other predicts asynchronous cluster articulation in Polish. Two groups of listeners performed a two-alternative forced choice identification task on stimuli that included affricated clusters, unaffricated clusters, affricates, and CəC-initial words. For L1 English listeners, the unaffricated cluster-initial items induced the slowest responses. For L1 Polish listeners, the lack of affrication facilitated cluster identification, while the CəC-initial words induced the slowed responses. The results suggest cross-language interaction by which Polish listeners equate L1 unaffricated clusters with L2 CəC-initial words, in accordance with the OP proposal.