The TIMIT corpus of read speech has been designed to provide speech data for the acquisition of acoustic-phonetic knowledge and for the development and evaluation of automatic speech recognition systems. TIMIT has resulted from the joint efforts of several sites under sponsorship from the Defense Advanced Research Projects Agency - Information Science and Technology Office (DARPA-ISTO). Text corpus design was a joint effort among the Massachusetts Institute of Technology (MIT), Stanford Research Institute (SRI), and Texas Instruments (TI). The speech was recorded at TI, transcribed at MIT, and has been maintained, verified, and prepared for CD-ROM production by the National Institute of Standards and Technology (NIST). This file contains a brief description of the TIMIT Speech Corpus. Additional information including the referenced material and some relevant reprints of articles may be found in the printed documentation which is also available from NTIS (NTIS# PB91-100354).
TIMIT contains a total of 6300 sentences, 10 sentences spoken by each of 630 speakers from 8 major dialect regions of the United States. Table 1 shows the number of speakers for the 8 dialect regions, broken down by sex. The percentages are given in parentheses. A speaker's dialect region is the geographical area of the U.S. where they lived during their childhood years. The geographical areas correspond with recognized dialect regions in U.S. (Language Files, Ohio State University Linguistics Dept., 1982), with the exception of the Western region (dr7) in which dialect boundaries are not known with any confidence and dialect region 8 where the speakers moved around a lot during their childhood.
Table 1: Dialect distribution of speakers
Dialect
Region(dr) #Male #Female Total
---------- --------- --------- ----------
1 31 (63%) 18 (27%) 49 (8%)
2 71 (70%) 31 (30%) 102 (16%)
3 79 (67%) 23 (23%) 102 (16%)
4 69 (69%) 31 (31%) 100 (16%)
5 62 (63%) 36 (37%) 98 (16%)
6 30 (65%) 16 (35%) 46 (7%)
7 74 (74%) 26 (26%) 100 (16%)
8 22 (67%) 11 (33%) 33 (5%)
------ --------- --------- ----------
8 438 (70%) 192 (30%) 630 (100%)
The dialect regions are:
dr1: New England
dr2: Northern
dr3: North Midland
dr4: South Midland
dr5: Southern
dr6: New York City
dr7: Western
dr8: Army Brat (moved around)
The text material in the TIMIT prompts (found in the file "prompts.doc") consists of 2 dialect "shibboleth" sentences designed at SRI, 450 phonetically-compact sentences designed at MIT, and 1890 phonetically-diverse sentences selected at TI. The dialect sentences (the SA sentences) were meant to expose the dialectal variants of the speakers and were read by all 630 speakers. The phonetically-compact sentences were designed to provide a good coverage of pairs of phones, with extra occurrences of phonetic contexts thought to be either difficult or of particular interest. Each speaker read 5 of these sentences (the SX sentences) and each text was spoken by 7 different speakers. The phonetically-diverse sentences (the SI sentences) were selected from existing text sources - the Brown Corpus (Kuchera and Francis, 1967) and the Playwrights Dialog (Hultzen, et al., 1964) - so as to add diversity in sentence types and phonetic contexts. The selection criteria maximized the variety of allophonic contexts found in the texts. Each speaker read 3 of these sentences, with each sentence being read only by a single speaker. Table 2 summarizes the speech material in TIMIT.
Table 2: TIMIT speech material
Sentence Type #Sentences #Speakers Total #Sentences/Speaker
------------- ---------- --------- ----- ------------------
Dialect (SA) 2 630 1260 2
Compact (SX) 450 7 3150 5
Diverse (SI) 1890 1 1890 3
------------- ---------- --------- ----- ----------------
Total 2342 6300 10
The speech material has been subdivided into portions for training and testing. The criteria for the subdivision is described in the file "testset.doc". THIS SUBDIVISION HAS NO RELATION TO THE DATA DISTRIBUTED ON THE PROTOTYPE VERSION OF THE CDROM.
Core Test Set:
The test data has a core portion containing 24 speakers, 2 male and 1 female from each dialect region. The core test speakers are shown in Table 3. Each speaker read a different set of SX sentences. Thus the core test material contains 192 sentences, 5 SX and 3 SI for each speaker, each having a distinct text prompt.
Table 3: The core test set of 24 speakers
Dialect Male Female
------- ------ ------
1 DAB0, WBT0 ELC0
2 TAS1, WEW0 PAS0
3 JMP0, LNT0 PKT0
4 LLL0, TLS0 JLM0
5 BPM0, KLT0 NLP0
6 CMJ0, JDH0 MGD0
7 GRT0, NJM0 DHC0
8 JLN0, PAM0 MLD0
Complete Test Set:
A more extensive test set was obtained by including the sentences from all speakers that read any of the SX texts included in the core test set. In doing so, no sentence text appears in both the training and test sets. This complete test set contains a total of 168 speakers and 1344 utterances, accounting for about 27% of the total speech material. The resulting dialect distribution of the 168 speaker test set is given in Table 4. The complete test material contains 624 distinct texts.
Table 4: Dialect distribution for complete test set
Dialect #Male #Female Total
------- ----- ------- -----
1 7 4 11
2 18 8 26
3 23 3 26
4 16 16 32
5 17 11 28
6 8 3 11
7 15 8 23
8 8 3 11
----- ----- ------- ------
Total 112 56 168
The speech and associated data is organized on the CD-ROM according to the following hierarchy:
/<CORPUS>/<USAGE>/<DIALECT>/<SEX><SPEAKER_ID>/7ltSENTENCE_ID>.<FILE_TYPE>
where,
CORPUS :== timit
USAGE :== train | test
DIALECT :== dr1 | dr2 | dr3 | dr4 | dr5 | dr6 | dr7 | dr8
(see Table 1 for dialect code description)
SEX :== m | f
SPEAKER_ID :== <INITIALS><DIGIT>
where,
INITIALS :== speaker initials, 3 letters
DIGIT :== number 0-9 to differentiate speakers with identical
initials
SENTENCE_ID :== <TEXT_TYPE><SENTENCE_NUMBER>
where,
TEXT_TYPE :== sa | si | sx
(see Section 2 for sentence text type description)
SENTENCE_NUMBER :== 1 ... 2342
FILE_TYPE :== wav | txt | wrd | phn
(see Table 5 for file type description)
Examples:
/timit/train/dr1/fcjf0/sa1.wav
(TIMIT corpus, training set, dialect region 1, female speaker, speaker-ID "cjf0", sentence text "sa1", speech waveform file)
/timit/test/df5/mbpm0/sx407.phn(TIMIT corpus, test set, dialect region 5, male speaker, speaker-ID "bpm0", sentence text "sx407", phonetic transcription file)
Online documentation and tables are located in the directory "timit/doc". A brief description of each file in this directory can be found in Section 6.
The TIMIT corpus includes several files associated with each utterance. In addition to a speech waveform file (.wav), three associated transcription files (.txt, .wrd, .phn) exist. These associated files have the form:
<BEGIN_SAMPLE> <END_SAMPLE> <TEXT><new-line>
.
.
.
<BEGIN_SAMPLE> <END_SAMPLE> <TEXT><new-line>where,
BEGIN_SAMPLE :== The beginning integer sample number for the segment (Note: The first BEGIN_SAMPLE of each file is always 0)END_SAMPLE :== The ending integer sample number for the segment (Note: Because of the transcription method used, the last END_SAMPLE in each transcription file may be less than the actual last sample in the corresponding .wav file)
TEXT :== <ORTHOGRAPHY> | <WORD_LABEL> | <PHONETIC_LABEL>
where,
ORTHOGRAPHY :== Complete orthographic text transcription
WORD_LABEL :== Single word from the orthography
PHONETIC_LABEL :== Single phonetic transcription code (See "phoncode.doc" for description of codes)
Table 5: Utterance-associated file types
File Type Description
--------- ------------------------------------------------------
.wav - SPHERE-headered speech waveform file. (See the "/sphere"
directory for speech file manipulation utilities.)
.txt - Associated orthographic transcription of the words the
person said. (Usually this is the same as the prompt, but
in a few cases the orthography and prompt disagree.)
.wrd - Time-aligned word transcription. The word boundaries
were aligned with the phonetic segments using a dynamic
string alignment program (see the printed documentation
section "Notes on the Word Alignments" and the lexical
pronunciations given in "timitdic.txt".)
.phn - Time-aligned phonetic transcription. (See the reprint
of the article by Seneff and Zue (1988), in the printed
documentation, and the section "Notes on Checking the
Phonetic Transcriptions" for more details on the phonetic
transcription protocols.)
Example transcriptions from the utterance in "/timit/test/dr5/fnlp0/sa1.wav"
Orthography (.txt):
0 61748 She had your dark suit in greasy wash water all year.
Word label (.wrd):
7470 11362 she
11362 16000 had
15420 17503 your
17503 23360 dark
23360 28360 suit
28360 30960 in
30960 36971 greasy
36971 42290 wash
43120 47480 water
49021 52184 all
52184 58840 year
Phonetic label (.phn):
(Note: beginning and ending silence regions are marked with h#)
0 7470 h#
7470 9840 sh
9840 11362 iy
11362 12908 hv
12908 14760 ae
14760 15420 dcl
15420 16000 jh
16000 17503 axr
17503 18540 dcl
18540 18950 d
18950 21053 aa
21053 22200 r
22200 22740 kcl
22740 23360 k
23360 25315 s
25315 27643 ux
27643 28360 tcl
28360 29272 q
29272 29932 ih
29932 30960 n
30960 31870 gcl
31870 32550 g
32550 33253 r
33253 34660 iy
34660 35890 z
35890 36971 iy
36971 38391 w
38391 40690 ao
40690 42290 sh
42290 43120 epi
43120 43906 w
43906 45480 ao
45480 46040 dx
46040 47480 axr
47480 49021 q
49021 51348 ao
51348 52184 l
52184 54147 y
54147 56654 ih
56654 58840 axr
58840 61680 h#
phoncode.doc - Table of phone symbols used in phonemic dictionary and
phonetic transcriptions
prompts.txt - Table of sentence prompts and sentence-ID numbers
spkrinfo.txt - Table of speaker attributes
spkrsent.txt - Table of sentence-ID numbers for each speaker
testset.doc - Description of suggested train/test subdivision
timitdic.doc - Description of phonemic lexicion
timitdic.txt - Phonemic dictionary of all orthographic words in prompts
A more extensive description of corpus design, collection, and transcription
can be found in the printed documentation.