Soundex is a phonetic algorithm for indexing names by sound, as pronounced in
English. The goal is for names with the same pronunciation to be encoded to the
same representation so that they can be matched despite minor differences in
spelling. Soundex is the most widely known of all phonetic algorithms and is
often used (incorrectly) as a synonym for "phonetic algorithm". Improvements to
Soundex are the basis for many modern phonetic algorithms. (Wikipedia, 2007)

Text::Soundex implements the original soundex algorithm developed by Robert
Russell and Margaret Odell, patented in 1918 and 1922, as well as a variation
called "American Soundex" used for US census data, and current maintained by the
National Archives and Records Administration (NARA).

The soundex algorithm may be recognized from Donald Knuth's The Art of Computer
Programming. The algorithm described by Knuth is the NARA algorithm.

WWW: http://search.cpan.org/dist/Text-Soundex/