At the surface level, progressive active and passive sentences are morphologically identical through the verb stem. In the example below, the identical regions are marked in bold font: 1. **The dog was punch**ing the bear (progressive active) 2. **The dog was punch**ed by the bear (passive) There is evidence that these regions are not acoustically identical: passive verb stems were longer than progressive active verb stems (Stromswold et al., 2002); however, only one speaker was tested. This study investigated whether the effect generalizes to other speakers, and a greater variety of predicates than tested previously. Seven native English speakers said progressive active (e.g., 1) or passive sentences (e.g., 2) aloud. We found that speakers reliably and consistently produced longer passive verb stems. Additionally, passive auxiliaries were reliably longer for some speakers. These findings suggest that progressive active and passive sentences are acoustically different prior to the region of morphosyntactic disambiguation, a property that listeners may or may not exploit to facilitate comprehension.