DSP II: Final presentation Vocoder - making music talk Van Damme Wim Hemeryck Martijn

Overview Summary LPC vocoder theory LPC vocoder demonstration Channel vocoder theory Channel vocoder demonstration

Summary LPC vocoder theory Encoder Decoder

Segmentation Use of a window function: hanning Without window overlap: not very smooth sound, many glitches With window overlap: slightly smoother, but sometimes messy pitch and intonation

V/U/S detector Goal was the lpc-10e standard: weighted voicing detection using several indicators → too little information, well hidden Tremain paper In the end: a fairly simple speaker independent (normalized!) voicing detector using MSF, ZCR and pitch information

Demonstration LPC No window overlap – High pitch (female) – Low pitch (male) Window overlap – High pitch (female) – Low pitch (male) – Own voice → more noise

LPC vocoder and music Basic idea: replace pulse train for voiced frames with periodic elementary note shapes of a music instrument, at a frequency corresponding to the pitch. No access to such libraries Therefore: channel vocoder…

Channel Vocoder theory

Channel vocoder demonstration Example ‘Around the world’ Real-Time