People Search: What Is Soundex?

What is Soundex?

Soundex is a system of indexing (and finding) names by the way they sound rather than the way they are spelled. Each name is assigned an index consisting of a letter and three numbers. When doing a Soundex search, two names match if they have the same index. For example, a Soundex search for Smith will match Smith, Smyth, Smitty, and possibly other names. If you aren't sure how to spell a particular name, Soundex may help you find it.

On the other hand, Soundex may find many matches that are puzzling and unhelpful. It may find too many matches and not show you any, in which case you will want to give it more details, e.g. first name or department. It is optimized to correct "English" type spelling mistakes, e.g. Z for S, but not H for J or V for W (as in Spanish or German names).

How to Derive an Index

If the same letter occurs twice in a row in the name, drop one occurance. For example, Lloyd becomes Loyd.
The letter in the index is the first letter of the name.
From the rest of the name, drop the vowels (A, E, I, O, U, Y), and "soundless" letters H and W.
From the remaining letters, assign numbers to the first three as follows:
- 1 - B, P, F, V
- 2 - C, G, J, K, Q, S, X, Z
- 3 - D, T
- 4 - L
- 5 - M, N
- 6 - R
If there are fewer than three letters, use 0 for the remaining number(s).

For the name Smith, it would work as follows:

S is the first letter of the name, so the index starts with S.
From the remaining letters (mith), drop the i and the h.
M = 5, T = 3, and there are no letters left so add a 0.
The index for Smith is S530