ARPABET
ARPABET is a set of phonetic transcription codes developed by Advanced Research Projects Agency as a part of their Speech Understanding Research project in the 1970s. It represents phonemes and allophones of General American English with distinct sequences of ASCII characters. Two systems, one representing each segment with one character and the other with one or two, were devised, the latter being far more widely adopted.
ARPABET has been used in several speech synthesizers, including Computalker for the S-100 system, SAM for the Commodore 64, SAY for the Amiga, TextAssist for the PC and Speakeasy from Intelligent Artefacts which used the Votrax SC-01 speech synthesiser IC. It is also used in the CMU Pronouncing Dictionary. A revised version of ARPABET is used in the TIMIT corpus.
Symbols
is indicated by a digit immediately following a vowel. Auxiliary symbols are identical in 1- and 2-letter codes. In 2-letter notation, segments are separated by a space.| AB | Description |
| 0 | No stress |
| 1 | Primary stress |
| 2 | Secondary stress |
| 3... | Tertiary and further stress |
| - | Silence |
| ! | Non-speech segment |
| + | Morpheme boundary |
| / | Word boundary |
| # | Utterance boundary |
| : | Tone group boundary |
| :1 or. | Falling or declining juncture |
| :2 or ? | Rising or internal juncture |
| :3 or. | Fall-rise or non-terminal juncture |
TIMIT
In TIMIT, the following symbols are used in addition to the ones listed above:| Symbol | IPA | Example | Description |
| AX-H | suspect | Devoiced | |
| BCL | obtain | closure | |
| DCL | width | closure | |
| ENG | Washington | Syllabic | |
| GCL | dogtooth | closure | |
| HV | ahead | Voiced | |
| KCL | doctor | closure | |
| PCL | accept | closure | |
| TCL | catnip | closure | |
| PAU | Pause | ||
| EPI | Epenthetic silence | ||
| H# | Begin/end marker |