Text::Soundex
This module implements the soundex algorithm as described by Donald Knuth in Volume 3 of The Art of Computer Programming. The algorithm is intended to hash words (in particular surnames) into a small space using a simple model which approximates the sound of the word when spoken by an English speaker. Each word is reduced to a four character string, the first character being an upper case letter and the remaining three being digits.

Text::Metaphone
Metaphone() is a function whereby a string/word is broken down into a rough approximation of its english phonetic pronunciation. Very similar in concept and purpose to soundex, but much more comprehensive in its approach.