Metaphone

Metaphone is an improved phonetic algorithm over Soundex that accounts for more English pronunciation rules (e.g., consonant combinations and silent letters), yielding higher accuracy.

Purpose

Provides more accurate English phonetic encoding than Soundex, reducing false matches.

Mechanism

Applies about 20 pronunciation rules: e.g., X→KS, TH→0, SH→X, silent-letter removal, etc. Outputs a variable-length alphanumeric string. Double Metaphone further handles multilingual and special cases, outputting a primary and a secondary code.

Use cases

More accurate person-name matching
Search engine spelling correction
Record linkage
Multilingual name processing

Examples

Input
```
Smith
```
Output
```
SM0X
```
More precise than Soundex

Common errors

Metaphone's complex rules make implementations error-prone: Use a mature library (e.g., doublemetaphone)

Related terms

Soundex is a phonetic algorithm that encodes English names by pronunciation as a letter plus three digits, giving similar-sounding names the same code; it is used for fuzzy person-name retrieval.

Fuzzy search is a search technique tolerant of spelling variations, matching approximate results based on edit distance, n-grams, or phonetic algorithms.

References