A real-time pitch modification system has been developed. The implemented processing scheme is based on hybrid deterministic/stochastic decomposition of the signal and includes extraction of instantaneous pitch, pitch-synchronous time-frequency analysis, parametrical morphing and synthesis. The scheme provides high quality output with considerably high naturalness. The aim of the presentation is to show capabilities of the designed real-time signal processing framework. The system implements speech-specific intonation change routines such as lowering, uplifting, tremolo etc. In order to make the presentation more expressive we designed a special singing mode in which the system automatically corrects wrong notes. The target melody and voice effects are specified using musical instruments digital interface (MIDI).