Soundex is a phonetic pattern-matching system created for the American census. Franklin Roosevelt directed the United States Bureau of Archives to develop a method of cataloguing the population that could handle variations in the spelling of similar surnames. Margaret K. Odell and Robert C. Russell developed Soundex and were awarded U.S. patents 1261167 (1918) and 1435663 (1922) for their efforts. The census filing card for each household was then filed under the Soundex method. Soundex has been applied to every census since and has been post-applied to census records back to 1880.
The purpose of Soundex is to sort similar-sounding names together, which is useful for dealing with contact information in a database application. For example, if I call a phone bank and give them my name (LeBlanc), they invariably spell it “LaBlanc” in the contact lookup form, but if the database uses Soundex properly, then I'll still be in the search-result list box.
For more information concerning Soundex and its history, refer to the following websites:
Here's how Soundex works. The first letter of a name is stored as the letter, and the following Soundex phonetic sounds are stored according to the following code:
Double letters with the same Soundex code, A, E, I, O, U, H, W, Y, and some prefixes, ...