Abstract: A karaoke apparatus includes a sound effect processing system provided in a microprocessor. The system decodes standard song data from an internal storage or an external storage connected to an extended system interface by a song decoding module; corrects pitches of sing voices by a pitch correcting system, so the pitches of the singing voices are corrected to the pitches of the standard song or close to the pitches of the standard song. The singing voices are processed with harmony adding, tonal modification and speed-changing by a harmony adding system to produce an effect of chorus being composed of three voice parts. A pitch evaluating system is used for comparing the pitch sequence of the singing voices with the pitch sequence of the standard song to draw a voice graph so as to visually show a difference between the pitches of the singing voices and the pitches of the standard song, while providing score and comment of the singing voices.