Soundex is the most widely known of all phonetic algorithms (in part because it is a standard feature of popular database software such as IBM Db2, PostgreSQL,[2] MySQL,[3] SQLite,[4] Ingres, MS SQL Server,[5] Oracle,[6] ClickHouse,[7] Snowflake[8] and SAP ASE.
[14] The National Archives and Records Administration (NARA) maintains the current rule set for the official implementation of Soundex used by the U.S.
[1] These encoding rules are available from NARA, upon request, in the form of General Information Leaflet 55, "Using the Census Soundex".
The correct value can be found as follows: Using this algorithm, both "Robert" and "Rupert" return the same string "R163" while "Rubin" yields "R150".
NYSIIS handles some multi-character n-grams and maintains relative vowel positioning, whereas Soundex does not.
Double Metaphone includes a much larger encoding rule set than its predecessor, handles a subset of non-Latin characters, and returns a primary and a secondary encoding to account for different pronunciations of a single word in English.
Philips created Metaphone 3 as a further revision in 2009 to provide a professional version that provides a much higher percentage of correct encodings for English words, non-English words familiar to Americans, and first and last names found in the United States.