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{{Short description|Transcribed corpus of American English}}
'''TIMIT''' is a corpus of phonemically and lexically transcribed speech of [[American English]] speakers of different sexes and dialects.  Each transcribed element has been delineated in time.

TIMIT was designed to further acoustic-phonetic knowledge and automatic speech recognition systems.  It was commissioned by [[DARPA]] and corpus design was a joint effort between the [[Massachusetts Institute of Technology]], [[SRI International]], and [[Texas Instruments]] (TI). The speech was recorded at TI, transcribed at MIT, and verified and prepared for publishing by the [[National Institute of Standards and Technology]] (NIST).<ref>
{{cite book  <!-- Note: {{cite conference}} inappropriately ignore the title (as chapter) -->
 | last1     = Fisher | first1=William M. 
 | last2     = Doddington | first2=George R. 
 | last3     = Goudie-Marshall | first3=Kathleen M.
 | chapter   = The DARPA Speech Recognition Research Database: Specifications and Status
 | title     = Proceedings of DARPA Workshop on Speech Recognition
 | pages     = 93–99
 | year      = 1986
}}</ref> There is also a telephone bandwidth version called NTIMIT (Network TIMIT).

TIMIT and NTIMIT are not freely available — either membership of the [[Linguistic Data Consortium]], or a monetary payment, is required for access to the dataset.

== Data ==
TIMIT contains ~5 hours of speech, of 10 sentences spoken by each of 630 speakers. The sentences were randomly sampled from a corpus of 2342 sentences. The speakers were native speakers of American English, classified under 8 major dialect regions: New England, Northern, North Midland, South Midland, Southern, New York City, Western, Army Brat (moved around). The speakers were 70% male and 30% female.<ref name=":0">{{Cite journal |last=Garofolo |first=John S. |last2=Lamel |first2=L. F. |last3=Fisher |first3=W. M. |last4=Fiscus |first4=Jonathan G. |last5=Pallett |first5=D. S. |last6=Dahlgren |first6=Nancy L. |date=1993-02-01 |title=DARPA TIMIT acoustic-phonetic continous speech corpus CD-ROM. NIST speech disc 1-1.1 |url=https://nvlpubs.nist.gov/nistpubs/Legacy/IR/nistir4930.pdf |journal=NIST Interagency/Internal Report |language=en |issue=4930}}{{source-attribution}}</ref>

Recordings were made in a noise-isolated recording booth at Texas Instrument, using a semi-automatic computer system (STEROIDS) to control the presentation of prompts to the speaker and the recording. Two-channel recordings were made using a [[Sennheiser]] HMD 414 headset-mounted microphone and a [[Brüel & Kjær]] 1/2" far-field pressure microphone (#4165). The speech was digitized at a [[Sampling (signal processing)|sample rate]] of 20&nbsp;kHz then and downsampled to 16&nbsp;kHz.<ref name=":0" />

==History==
The TIMIT telephone corpus was an early attempt to create a database with speech samples.<ref>{{cite journal |title=STC-TIMIT Generation of a single-channel telephone corpus |author=Morales, Nicolas and Tejedor, Javier and Garrido, Javier and Colas, Jose and Toledano, Doroteo T |journal=Proceedings of the Sixth International Language Resources and Evaluation (LREC'08) |pages=391–395 |year=2008 }}</ref> It was published in the year 1988 on [[CD-ROM]] and consists of only 10 sentences per speaker. Two 'dialect' sentences were read by each speaker, as well as another 8 sentences selected from a larger set <ref>{{cite tech report |year=1986 |publisher= DARPA (SAIC-86/1546)|author=[[Lori Lamel|Lori F Lamel]] and Robert H. Kassel and Stephanie Seneff |title=Speech Database Development: Design and Analysis of the Acoustic-Phonetic Corpus}}</ref> Each sentence averages 3 seconds long and is spoken by 630 different speakers.<ref>{{cite tech report |doi=10.6028/nist.ir.4930 |year=1993 |publisher=National Institute of Standards and Technology |author=John S Garofolo and [[Lori Lamel|Lori F Lamel]] and William M Fisher and Jonathan G Fiscus and David S Pallett and Nancy L Dahlgren |title=DARPA TIMIT }}</ref> It was the first notable attempt in creating and distributing a [[speech corpus]] and the overall project has produced costs of 1.5 million US$.<ref>{{cite conference |doi=10.21437/interspeech.2018-1185 |year=2018 |publisher=ISCA |author=Nattanun Chanchaochai and Christopher Cieri and Japhet Debrah and Hongwei Ding and Yue Jiang and Sishi Liao and Mark Liberman and Jonathan Wright and Jiahong Yuan and Juhong Zhan and Yuqing Zhan |title=GlobalTIMIT: Acoustic-Phonetic Datasets for the World's Languages |conference=Interspeech 2018 }}</ref>

An update was released in October 1990. It included<ref name=":0" />

* full 630-speaker corpus;
* checked and corrected transcriptions;
* word-alignment transcriptions;
* NIST SPHERE-headered waveform files and header manipulation software;
* phonemic dictionary;
* new test and training subsets balanced for dialectal and phonetic coverage;
* more extensive documentation.

The full name of the project is DARPA-TIMIT Acoustic-Phonetic Continuous Speech Corpus<ref>{{cite conference |title=WTIMIT: The TIMIT Speech Corpus Transmitted Over The 3G AMR Wideband Mobile Network. |author=Bauer, Patrick and Scheler, David and Fingscheidt, Tim |conference=LREC |year=2010 }}</ref> and the acronym TIMIT stands for Texas Instruments/Massachusetts Institute of Technology. The main reason why a corpus of telephone speech was created was to train [[speech recognition]] software. In the Blizzard challenge, different software has the obligation to convert audio recordings into textual data and the TIMIT corpus was used as a standardized baseline.<ref>{{cite conference |title=The NITech text-to-speech system for the Blizzard Challenge 2016 |author=Sawada, Kei and Asai, Chiaki and Hashimoto, Kei and Oura, Keiichiro and Tokuda, Keiichi |conference=Blizzard Challenge 2016 Workshop |year=2016 }}</ref>

==See also==
* [[Comparison of datasets in machine learning]]

==References==
<references/>

==External links==
* [http://catalog.ldc.upenn.edu/LDC93S1 TIMIT Acoustic-Phonetic Continuous Speech Corpus]

{{Corpus linguistics}}

[[Category:Applied linguistics]]
[[Category:Computational linguistics]]
[[Category:English corpora]]
[[Category:Dialectology]]
[[Category:Linguistic research]]
[[Category:Phonetics]]
[[Category:Speech recognition]]
[[Category:Speech processing]]
[[Category:Datasets in machine learning]]


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