phonetic index
n.
An ordered list of materials organized under codes that represent the sound of names or words.
Notes
A phonetic index makes it possible to look up something without knowing how it was spelled. Many censuses have a phonetic index to name. Most techniques to create index codes use the first letter of the name followed by digits representing subsequent sounds. For example, Smith, Smythe, and Smyth might all be coded S530. Different techniques, such as Russell's Soundex, Simplified Soundex, American Soundex, and Miracode, use slightly different rules, producing different codes.