# Log Area Ratios

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Log Area Ratios

Log Area Ratios (LAR) can be used to represent Reflection Coefficients (another form for Linear Prediction Coefficients) for transmission over a channel. While not as efficient as Line Spectral Pairs (LSPs), Log Area Ratios are much simpler to compute. Let $r_k$ be the kth reflection coefficient of a filter, the kth LAR is:

: $A_k = log\left\{1+r_k over 1-r_k\right\}$

Use of Log Area Ratios have now been mostly replaced by Line Spectral Pairs, but older codecs, such as GSM-FR use LARs.