The Soundex algorithm indexes words by their sound when pronounced in English, for example to account for differences in spelling.

This public domain Common Lisp implementation of Soundex was originally in the JWZ tarball of the CMU AI repository.

Soundex is ASDF-installable.

ASDF-install package (obsolete)

levenshtein also measures the distances between words, although it is not based on sound.

Natural Language Processing text