rt_lpc is a light-weight application that performs real-time LPC analysis and synthesis. It features the following:

• real-time LPC analysis
• real-time LPC synthesis
• visualization of original, predicted, and error waveforms
• visualization of vocal tract shape from LPC coefficients
• adjustable LPC analysis order
• adjustable synthesis pitch shift
• MIDI controlled pitch (hit ‘m’)
• lots of other choices (pitch pulse source selection, emphasis filter)
• STFT plot
• modular LPC library
• available on MacOS X, Linux, and Windows under GPL
• part of the sndtools distribution

soundlab.cs.princeton.edu/software/rt_lpc/
en.wikipedia.org/wiki/Linear_predictive_coding
github.com/lewark/lpc.lv2