Metaphone

Metaphone is a phonetic algorithm used to index English words by their pronunciation. It was developed as an improvement over Soundex, aiming to produce codes that reflect how words sound rather than how they are spelled.

Invented by Lawrence Phillips in 1990, the original Metaphone encodes a word into a phonetic key by applying rules of English pronunciation and discarding letters that carry little phonetic weight. Words that sound alike should share the same Metaphone key, facilitating fuzzy matching in search and data retrieval.

Variants exist. Metaphone 2 expands the rule set to address more spellings and dialects, strengthening coverage of English pronunciations. Double Metaphone, another refinement, can emit two encodings to represent alternate pronunciations and accents, improving matching across varieties of speech.

Applications include matching names in genealogical databases, deduplicating records in data mining, spell checking, and search algorithms where pronunciation-based matching improves retrieval results.

Limitations include its English focus, potential misrepresentation of non-English names, variation across accents, and the inherent ambiguity of pronunciation. Metaphone encodings can produce false positives and false negatives, and results should be treated as probabilistic rather than exact phonetic transcriptions.