The Extended Speech Assessment Methods Phonetic Alphabet (X-SAMPA) is a variant of SAMPA developed in 1995 by John C. Wells, professor of phonetics at University College London.[1] It is designed to unify the individual language SAMPA alphabets, and extend SAMPA to cover the entire range of characters in the 1993 version of International Phonetic Alphabet (IPA). The result is a SAMPA-inspired remapping of the IPA into 7-bit ASCII.
SAMPA was devised as a hack to work around the inability of text encodings to represent IPA symbols. Later, as Unicode support for IPA symbols became more widespread, the necessity for a separate, computer-readable system for representing the IPA in ASCII decreased. However, X-SAMPA is still useful as the basis for an input method for true IPA.
Summary
Notes
The IPA symbols that are ordinary lower case letters have the same value in X-SAMPA as they do in the IPA.
X-SAMPA uses backslashes as modifying suffixes to create new symbols. For example, O is a distinct sound from O\, to which it bears no relation. Such use of the backslash character can be a problem, since many programs interpret it as an escape character for the character following it. For example, such X-SAMPA symbols do not work in EMU, so backslashes must be replaced with some other symbol (e.g., an asterisk: '*') when adding phonemic transcription to an EMU speech database. The backslash has no fixed meaning.
X-SAMPA diacritics follow the symbols they modify. Except for ~ for nasalization, = for syllabicity, and ` for retroflexion and rhotacization, diacritics are joined to the character with the underscore character _.
The underscore character is also used to encode the IPA tiebar: k_p codes for /k͡p/.
The numbers _1 to _6 are reserved diacritics as shorthand for language-specific tone numbers.
The IETF language tags registry has assigned fonxsamp as the subtag for text transcribed in X-SAMPA.[2]
Asterisks (*) mark sounds that do not have X-SAMPA symbols. Daggers (†) mark IPA symbols that have recently been added to Unicode. Since April 2008, the latter is the case of the labiodental flap, symbolized by a right-hook v in the IPA: . A convention for the labiodental flap does not yet exist in X-SAMPA.