Uses of Linear Predictive Coding (LPC)

LPC, a statistical method for predicting future values of a waveform on the basis of its past values¹, is often used to obtain a spectral envelope.

LPC differs from formant tracking in that:

• the waveform remains in the time domain; resonances are described by the coefficients of an all-pole filter.

• altering resonances is difficult since editing IIR filter coefficients can result in an unstable filter.

• analysis may be applied to a wide range of sounds.

LPC is often used to determine the filter in a source-filter model of speech² which:

• characterizes the response of the vocal tract.
• reconstitutes the speech waveform when driven by the correct source.