1. Recommended range of speech and pitch control (1) Sampling frequency: Fs to be speed controlled is 4.0 to 32.0kHz. The recommended is 12.8kHz to 32.0kHz. (2) Recommended speed control function: 0.8 to 2.0 times much (3) Recommended pitch control function: ±10% 2. Speed control function is only effective in sound. Not effective in melody and sound effect.