If learning phonetic contrasts of a language is considered the result of selective attention, it then may be possible to redirect listeners’ attention towards non-native contrasts. In this paper we present an experiment carried out in order to investigate the perception of non-native contrasts by Spanish listeners, in particular, we want to analyse the effects of cue-enhancement on their perceptual performances of 25 different English words containing natural and enhanced sibilants, all presented in clear speech. The results of the experiments showed that the effects of the enhancement varied greatly among the consonants, and across the different vocalic contexts. Moreover, the results did not seem to correlate with subjects’ variables, such as subject’s age, time period of L2 learning or age of L2 learning, although error patterns could be related to the phonological system of Spanish listeners