Caverphone

The Caverphone within linguistics and computing, is a phonetic matching algorithm^[1][2] invented to identify English names with their sounds, originally built to process a custom dataset compound between 1893 and 1938 in southern Dunedin, New Zealand.^[3] Started from a similar concept as metaphone, it has been developed to accommodate and process general English since then.^[3]

The Caverphone was created by David Hood in the Caversham Project at the University of Otago in New Zealand in 2002, revised in 2004. 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, New Zealand).

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

The algorithm is as follows:

1. Convert to lowercase
2. Remove anything not A-Z
3. If the name starts with...
   1. cough, replace it by cou2f
   2. rough, replace it by rou2f
   3. tough, replace it by tou2f
   4. enough, replace it by enou2f
   5. gn, replace it by 2n
4. If the name ends with
   1. mb, replace it by 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. 2
   2. 3
7. put six 1 on the end
8. take the first six characters as the code

1. Start with a word
2. Convert to lowercase
3. Remove anything not in the standard alphabet (typically a-z)^{[note 1]}
4. Remove final e
5. 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. trough make it trou2f
   6. gn make it 2n
6. If the name ends with
   1. mb make it m2
7. 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. an initial vowel^{[note 2]} with an A
   19. all other vowels with a 3
   20. j with y
   21. an initial y3 with Y3
   22. an initial y with A
   23. y with 3
   24. 3gh3 with 3kh3
   25. gh with 22
   26. g with k
   27. groups of the letter s with a S
   28. groups of the letter t with a T
   29. groups of the letter p with a P
   30. groups of the letter k with a K
   31. groups of the letter f with a F
   32. groups of the letter m with a M
   33. groups of the letter n with a N
   34. w3 with W3
   35. wh3 with Wh3
   36. if the name ends in w replace the final w with 3
   37. w with 2
   38. an initial h with an A
   39. all other occurrences of h with a 2
   40. r3 with R3
   41. if the name ends in r replace the final r with 3
   42. r with 2
   43. l3 with L3
   44. if the name ends in l replace the final l with 3
   45. l with 2
8. remove all 2s
9. if the name end in 3, replace the final 3 with A
10. remove all 3s
11. put ten 1s on the end
12. take the first ten characters as the code

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

Lee -> lee
lee -> le
le -> l3
l3 -> L3
L3 -> LA
LA -> LA1111111111
LA1111111111 -> LA11111111

Thompson -> thompson
thompson -> th3mps3n
th3mps3n -> th3mpS3n
th3mpS3n -> Th3mpS3n
Th3mpS3n -> Th3mPS3n
Th3mPS3n -> Th3MPS3n
Th3MPS3n -> Th3MPS3N
Th3MPS3N -> T23MPS3N
T23MPS3N ->  TMPSN
TMPSN1111111111 -> TMPSN11111

• Soundex
• New York State Identification and Intelligence System
• Match rating approach
• Metaphone
• Cologne phonetics

• Caversham Project - Caversham data set of names and accents in the southern part of Dunedin, New Zealand in 1893-1938.
• Original (2002) Caverphone algorithm
• Revised (2004) Caverphone algorithm
• Implementations:
  • C# Revised Implementation^{[permanent dead link‍]}
  • Java implementation in the Apache Commons Codec project
  • PHP implementation
  • Python Implementation caverphone algorithm (version 2.0) - AdvaS Advanced Search project