Some studies have been reporting encouraging results concerning the possibilities of combining voice and its visual representation for language learning. Following this line of investigation this paper explores the potential impact of two distinct visualization styles for the learning of English pronunciation of syllables for non-native speakers: a) highlighting syllables and b) the visualization of the produced sound wave. In order to evaluate the benefits of the two different styles three distinct digital tool prototypes were created in order to test four study conditions. The conditions under evaluation were a) teaching syllables without the support of any digital tool; b) teaching using a prototype that highlighted the syllables under study; c) using a prototype that displayed the sound wave of the syllable to be learnt and d) a prototype that combined the functionality of b) and c). Results suggest that the combined approach seems to be as effective as the traditional classroom approach of teaching the syllables. However, more research is needed in order to consolidate the findings, being able to explore in more detail how is the learning process occurring and to what extend the tools developed can be integrated into classroom practice.