Kelly-Lochbaum Vocal Tract Model

• Wave impedance in section $i$:
  $$R_i = \frac{\rho c}{A_i}$$
  where $A_i =$ cross-sectional area of tube
• Reflection coefficient at $i$th cylinder-cylinder junction:
  $$k_i \isdef \frac{R_i - R_{i-1}}{R_i + R_{i-1}}$$

• Can be interpreted either as a digital waveguide or wave digital model of the vocal tract.
• For correct tuning of two or more resonance (formants), digital waveguide models are required.