What is Caverphone designed for?

Caverphone was created for the Caversham project at the University of Otago to match often-misspelled New Zealand surnames from the late 1800s and early 1900s. It handles NZ, Australian and English pronunciations well.

Why is the code always 10 characters?

Caverphone 2.0 fixes the output length at ten characters, right-padding short codes with the digit 1. This makes codes easy to store in fixed-width fields and compare directly.

How is it different from Soundex?

Caverphone applies a long, ordered list of substitution rules rather than a single letter table, so it captures more pronunciation nuance and is better tuned to the names it was built for.

Is this Caverphone 1.0 or 2.0?

This is Caverphone 2.0, the revised 2004 specification, which is more accurate and the version most libraries implement today.

Does it work outside New Zealand?

It works on any English-style name but is most accurate for the NZ/Australian/English names it was designed for. For German names use Cologne Phonetics; for general English use Metaphone.

Caverphone Encoder — Gera Tools

What this tool does

Caverphone is a phonetic matching algorithm created by David Hood at the University of Otago for the Caversham project, which linked New Zealand electoral and census records full of inconsistent spellings. This encoder implements Caverphone 2.0, the 2004 revision, producing a fixed 10-character code in your browser. It is especially good at matching New Zealand, Australian and English surnames.

How it works

Caverphone 2.0 is defined as a strict sequence of string substitutions applied in a fixed order — the order itself is part of the specification. It begins by removing a trailing E and rewriting special openings:

^cough -> cou2f     ^gn -> 2n        mb$ -> m2
ce -> se            ci -> si         tch -> 2ch
c/q/x -> k          v -> f           ph -> fh
b -> p              sh -> s2         z -> s

After the consonants are normalised, vowels are coded (a leading vowel becomes A, others become 3), then runs of identical consonant letters are collapsed (S+, T+, P+, K+ and so on). Finally the placeholder digits 2 and 3 are stripped, the result is right-padded with the digit 1, and it is truncated to exactly ten characters.

Example and notes

Reference values match the widely used implementations: “Stevenson” gives STFNSN1111, “Thompson” gives TMPSN11111, “Peter” gives PTA1111111 and “Caverphone” itself gives KFFN111111. Because every code is the same fixed width, you can store Caverphone keys in a database column and compare them with a simple equality test. Use it as a candidate-generation step for genealogy, electoral-roll or historical-record matching, then confirm with closer comparison. All encoding happens locally — no data is sent anywhere.