Soundex

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.

Purpose

Encodes names by English pronunciation so that names spelled differently but pronounced alike can match.

Mechanism

Keep the first letter + drop the vowels and h/w/y (a,e,i,o,u,h,w,y) + map consonants to digits by group (b,f,p,v→1; c,g,j,k,q,s,x,z→2; d,t→3; l→4; m,n→5; r→6) + collapse adjacent same-group codes + pad with zeros to 3 digits.

Use cases

Person-name database retrieval
Genealogy search
Spelling correction
Record deduplication

Examples

Input
```
Robert
```
Output
```
R163
```
Robert and Rupert share the same code

Common errors

Soundex suits English only; other languages need adjustments: Use a language-specific phonetic algorithm

Related terms

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.

Levenshtein Distance

The Levenshtein distance is the minimum number of single-character insertions, deletions, and substitutions needed to make two strings identical.

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

References