This paper describes the perception of intervocalic stop voicing in European Portuguese (EP) stimuli without a stop burst, when varying three acoustic cues: Vowel duration, stop duration, and voicing maintenance during stop closure. Perceptual stimuli were generated using biomechanical modeling. First, a discrimination experiment was conducted to determine the listeners' perceptual sensitivity to the voicing maintenance cue. Second, an identification experiment was conducted to examine the effect and interaction of vowel duration, stop duration, and voicing maintenance during stop closure on the voiced/voiceless identification responses of EP listeners. The results of the discrimination test show that voicing maintenance differences have a significant effect as soon as they exceed a certain threshold. In the identification experiment, evidence was found that only the two factors vowel duration and voicing maintenance significantly influence the listeners' decisions, but not stop duration. The ratio between stop duration and vowel duration plays a major role in distinguishing stop voicing, but only for highly devoiced stimuli. It is shown that in stimuli without a stop burst, both voicing maintenance, as a major but not required cue, and vowel duration are important acoustic cues for stop voicing distinctions in EP.