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.
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