What is "soundex"

Soundex is a phonetic algorithm for indexing names by sound, as pronounced in English. The aim is for homophones to be encoded for the same representation, so that they can be combined despite minor differences in spelling. The algorithm primarily encodes consonants. A vowel will not be encoded unless it is the first letter.

Soundex is the best known of all phonetic algorithms (partly because it is a standard feature of popular database software such as Postgresql, Mysql, MS SQL Server and Oracle ) and is often used (incorrectly) as a synonym for "phonetic algorithm". Improvements to Soundex are the basis for many modern phonetic algorithms.