In a previous work we presented a system for transcribing spoken rhythms into a symbolic score. Thereafter, the system was extended to process the vocal stream in real-time in order to allow a musician to use it as a voice-driven drum generator. Extensions to this work are the following. First we achieved a study of the system classification accuracy based on typical onomatopoeia used in western beat boxing, with the perspective of building a general supervised model for immediate use. Also, we want the user to be able to generate expressive rhythms, beyond the symbolic drum representation. Thus we considered a class-specific mapping of continuous vocal stream descriptors with either effects or synthesis parameters of the drum generator. The extraction of the symbolic drum stream is implemented in the BillaBoop VST Core plug-in. The class-specific mapping and the sound synthesis are carried out in Plogue Bidule 1 framework. All these components are integrated into a low-latency application that allows its use for live performances.