Speech coding

• Speech can be coded at many levels.
• Lower bit-rates are achieved by imposing more constraints of the speech production mechanism are applied
• Failure becomes more catastrophic as the bit rate is reduced

 
• Waveform coders
  • Pulse Code Modulation (PCM)
  • Differential Pulse Code Modulation (DPCM)
  • Adaptive Differential Code Modulation (ADPCM)
  • Example: lossless waveform coding
• Sub-band coders
• Linear prediction vocoders
  • Parameter updating
  • Example: LPC10
• Formant coders
• Multi-pulse coders
• Backwards adaptation
• CELP coders