LPC Spectral Envelope

$$Y_m(\omega_k) = \frac{g}{A\left(e^{j\omega_k}\right)} \quad \hbox{or}\quad \frac{g}{\left\vert A\left(e^{j\omega_k}\right)\right\vert}$$

• Typically, $g = \left\Vert\,E\,\right\Vert _2$
• Note that $\log\left[A\left(e^{j\omega_k}\right)\right]$ is zero mean
• For voice, $M$ should be at least twice the number of spectral formants.
• For best results, use the Bark bilinear transform¹to warp the spectral axis.