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0.5.11 Metaphone Algorithm

Like the previously discussed Soundex algorithm, Metaphone is a system for transforming words into codes based on phonetic properties. However, unlike Soundex which operates on a letter-by-letter scheme, Metaphone analizes both single consonants and groups of letters called dipthongs.

Metaphone was invented by Lawrence Philips and first described in Computer Language magazine in December 1990.

The Metaphone algorithm operates by first removing non-English letters and characters from the word being processed. Next, all vowels are also discarded unless the word begins with an initial vowel in which case all vowels except the initial one are discarded. Finally all consonents and groups of consonents are mapped to their Metaphone code. The rules for grouping consonants and groups thereof then mapping to metaphone codes are fairly complicated; for a full list of these conversions check out the comments in the source code section.

Scott Gasch