LP inverse filtering flattens signals into spectrally whitened residuals

Evidence

The IIR filter 1/A(z) is called the synthesis filter, where A(z) = 1 − apz−p and ap are the coefficients from Equation (3.33). The FIR filter A(z) itself is called the inverse filter. If it acts on the original signal, a residual signal that is spectrally flattened (whitened) is obtained. — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 435

Categorization

• DEFINE: Defines synthesis filter, inverse filter, and the whitening operation in one compact causal sketch.
• SHARE: The synthesis/inverse filter pair being reciprocal spectral operations is a clean nugget for someone working with LPC vocoders.
• corroborated: 3 independent passages support this claim — Ville Pulkki, Matti Karjalainen, Communication Acoustics- An…, 435