timit

TIMIT, short for the TIMIT Acoustic-Phonetic Continuous Speech Corpus, is a widely used dataset for researching acoustic-phonetic and speech-recognition systems. It was developed in the 1980s by Texas Instruments and MIT Lincoln Laboratory, with support from the U.S. DARPA program, to provide a standardized resource for evaluating speech technology across dialects and phonetic inventories.

The corpus comprises recordings from 630 native American English speakers representing eight regional dialects. Each speaker read a set of phonetically balanced sentences, resulting in about 6,300 sentences in total. Recordings are two-channel, sampled at 16 kHz, and accompanied by comprehensive transcripts, including time-aligned orthographic, phonetic, and hierarchical phoneme-level annotations. The phonetic transcription uses a 61-phone inventory (with silences and related labels) and is aligned to the audio to enable precise phoneme timing. The data are typically partitioned into training and test subsets, with 462 speakers in the training set and 168 in the test set.

TIMIT is designed to support a range of research activities, including acoustic-phonetic analysis, phoneme recognition, and robust speech recognition across dialects. Its standardized structure, detailed annotations, and balanced dialect representation have made it a benchmark dataset for evaluating and comparing speech-processing algorithms.

Access to TIMIT is distributed by the Linguistic Data Consortium (LDC) under licensing arrangements, rather than as a completely free resource. The dataset remains a foundational tool in academic and industrial speech research, contributing to the development and evaluation of models and phonetic algorithms.