Computer assisted language learning (CALL) comprises a wide range of information technologies that aim to broaden the context of teaching by getting advantages of IT. For example, a few efforts have been put on including a combination of voice and its visual representation for language learning, and some studies are reporting positive outcomes. However, more research is needed in order to assess the impact caused by specific visualization styles such as: highlighting syllables and/or wave of sound. In order to explore this issue, we focused at measuring the potential impact that two distinct visualization styles and its combination can have on teaching children the pronunciation of English as a second language. We built a prototype which was designed to assist students while learning pronunciation of syllables. This system was employing two different real-time interactive visualization styles. One of these visualization styles utilizes audio capturing and processing, using a recent technology development: Web Audio API.We evaluated the effect of our prototype with an experiment with children aged from 9 to 11years old. We followed an experimental approach with a control group and three experimental groups. We tested our hypothesis that states that the use of a combined visualization style can have greater impact at learning pronunciation in comparison with traditional learning approach.Initial descriptive analyses were suggesting promising results for the group that used the combined visualization prototype. However, additional statistical analyses were carried out in order to measure the effect of prototype as accurately as possible within the constraints of our study. Further analyses provided evidence that our combined visualizations prototype has positively affected the learning of pronunciation. Nonetheless, the difference was not big comparing to the system that employed only wave of sound visualization. Ability to perceive visual information differs among individuals. Therefore, further research with different sample division is needed to determine whether is the combination of visualizations that does the effect, or is the wave in itself. Slitting groups based on this characteristic and perform the testing will be considered for the future research.Eventually, we can be confident to continue exploring further the possibility of integrating our proposed combination of two visualization styles in teaching practices of second language learning, due to positive outcomes that our current research outlined. In addition, from a technological perspective, our work is at the forefront of exploring the use of tools such as Web Audio API for CALL.