or worse, a small error might make the prediction filter unstable. There are more advanced representations such as log area ratios (LAR), line spectral pairs (LSP) decomposition and reflection coefficients. Of these, especially LSP decomposition has gained popularity since it ensures the stability of the predictor, and spectral errors are local for small coefficient deviations. Applications LPC is the most widely used method in speech coding and speech synthesis. It is generally used for speech analysis and resynthesis. It is used as a form of voice compression by phone companies, such as in the GSM standard, for example. It is also used for secure wireless, where voice must be digitized, encrypted and sent over a narrow voice channel; an early example of this is the US government's Navajo I. LPC synthesis can be used to construct vocoders where musical instruments are used as an excitation signal to the time-varying filter estimated from a singer's speech. This is somewhat popular in electronic music. Paul Lansky made the well-known computer music piece notjustmoreidlechatter using linear predictive coding. More Than Idle Chatter A 10th-order LPC was used in the popular 1980s Speak & Spell educational toy. LPC predictors are used in Shorten, MPEG-4 ALS, FLAC, SILK audio codec, and other lossless audio codecs. LPC received some attention as a tool for use in the tonal analysis of violins and other stringed musical instruments. See also Akaike information criterion Audio compression Code-excited linear prediction (CELP) FS-1015 FS-1016 Generalized filtering Linear prediction Linear predictive analysis Pitch estimation Warped linear predictive coding References Robert M. Gray, IEEE Signal Processing Society, Distinguished Lecturer Program Further reading External links real-time LPC analysis/synthesis learning software 30 years later Dr Richard Wiggins Talks Speak & Spell development Audio codecs Lossy compression algorithms Speech codecs Digital signal processing Japanese inventions