Metaphone is a phonetic algorithm, an algorithm published in 1990 for indexing words by their English pronunciation. The algorithm produces variable length keys as its output, as opposed to Soundex's fixed-length keys. Similar sounding words share the same keys.
metaphone(str) → returns string
This compound word is the longest word published with 79 letters according to the 1996 Guinness Book of World Records
Expected Result: TNTM
Expected Result: TRK/TRK
Adding a word changes the whole metaphone
Expected Result: TRK/STRT