The Caverphone phonetic matching algorithm was created by David Hood in the Caversham Project at the University of Otago

University of Otago

The University of Otago in Dunedin is New Zealand's oldest university with over 22,000 students enrolled during 2010.The university has New Zealand's highest average research quality and in New Zealand is second only to the University of Auckland in the number of A rated academic researchers it...

 in New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 in 2002. It was created to assist in data matching between late 19th century and early 20th century electoral rolls, where the name only needed to be in a "commonly recognisable form". The algorithm was intended to apply to those names that could not easily be matched between electoral rolls, after the exact matches were removed from the pool of potential matches). The algorithm is optimised for accents present in the study area (southern part of the city of Dunedin

Dunedin

Dunedin is the second-largest city in the South Island of New Zealand, and the principal city of the Otago Region. It is considered to be one of the four main urban centres of New Zealand for historic, cultural, and geographic reasons. Dunedin was the largest city by territorial land area until...

, New Zealand).

The rules of the algorithm are applied consecutively to any particular name, as a series of replacements.

The exact algorithm is as follows:

1. Convert to lowercase
2. Remove anything not A-Z
3. If the name starts with
   1. cough make it cou2f
   2. rough make it rou2f
   3. tough make it tou2f
   4. enough make it enou2f
   5. gn make it 2n
4. If the name ends with
   1. mb make it m2
5. Replace
   1. cq with 2q
   2. ci with si
   3. ce with se
   4. cy with sy
   5. tch with 2ch
   6. c with k
   7. q with k
   8. x with k
   9. v with f
   10. dg with 2g
   11. tio with sio
   12. tia with sia
   13. d with t
   14. ph with fh
   15. b with p
   16. sh with s2
   17. z with s
   18. any initial vowel with an A
   19. all other vowels with a 3
   20. 3gh3 with 3kh3
   21. gh with 22
   22. g with k
   23. groups of the letter s with a S
   24. groups of the letter t with a T
   25. groups of the letter p with a P
   26. groups of the letter k with a K
   27. groups of the letter f with a F
   28. groups of the letter m with a M
   29. groups of the letter n with a N
   30. w3 with W3
   31. wy with Wy
   32. wh3 with Wh3
   33. why with Why
   34. w with 2
   35. any initial h with an A
   36. all other occurrences of h with a 2
   37. r3 with R3
   38. ry with Ry
   39. r with 2
   40. l3 with L3
   41. ly with Ly
   42. l with 2
   43. j with y
   44. y3 with Y3
   45. y with 2
6. remove all
   1. 2s
   2. 3s
7. put six 1s on the end
8. take the first six characters as the code

Examples

Lee -> lee

lee -> l33

l33 -> L33

L33 -> L

L -> L111111

L111111 -> L11111

Thompson -> thompson

thompson -> th3mps3n

th3mps3n -> th3mpS3n

th3mpS3n -> Th3mpS3n

Th3mpS3n -> Th3mPS3n

Th3mPS3n -> Th3MPS3n

Th3MPS3n -> Th3MPS3N

Th3MPS3N -> T23MPS3N

T23MPS3N ->  TMPSN

TMPSN111111 -> TMPSN1

External links

• Caversham Project http://caversham.otago.ac.nz/
• Original (2002) Caverphone algorithm http://caversham.otago.ac.nz/files/working/ctp060902.pdf
• Revised (2004) Caverphone algorithm http://caversham.otago.ac.nz/files/working/ctp150804.pdf
• Implementation in the Apache Commons Codec project
• C# Revised Implementation: http://sounditout.codeplex.com/