Soundex is a phonetic algorithm for indexing names by sound, as
pronounced in English. The goal is for homophones to be encoded
to the same representation so that they can be matched despite
minor differences in spelling. The algorithm mainly encodes
consonants; a vowel will not be encoded unless it is the first
letter. Soundex is the most widely known of all phonetic
algorithms (in part 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. Soundex was developed by Robert
C. Russell and Margaret K. Odell and patented in 1918 and 1922.
A variation called American Soundex was used in the 1930s for a
retrospective analysis of the US censuses from 1890 through
1920. The Soundex code came to prominence in the 1960s when it
was the subject of several articles in the Communications and
Journal of the Association