This article reports the results of two experiments investigating the combined role of vowel length and length of fricative voicing in the identification, by Brazilians, of minimal pairs such as casa /z/ – caça /s/ produced by speakers of Spanish (L1). In Experiment 1, stimuli were manipulated so that length of voicing in the fricative was tested in two levels (100% or 0% of voicing) and vowel length was tested in four levels (25%, 50%, 75% and 100% of the length of the total vowel). In Experiment 2, voicing length was tested in three levels (25%, 50% and 75% of voicing), combined with the four levels of vowel length (25%, 50%, 75% and 100% of the length of the total vowel). Both experiments were run on TP Software ( Rauber et al. 2012), and forty Brazilian listeners with no experience with Spanish took part in both tasks. The results show an interaction between the two cues, especially in the stimuli with no full voicing in the fricative. These findings provide additional evidence to the gradient status of speech in production and perceptual phenomena ( Albano 2001; Albano 2012; Perozzo 2017), besides shedding light on the teaching of Brazilian Portuguese as an Additional Language.