UCL Psychology Speech Group Dysfluency Database


The Dysfluency database consists of recordings of 61 speakers who have been studied by the UCL Psychology department speech group as part of their research into stammering. The database is a unique resource for researchers interested in the linguistic, phonetic and acoustic properties of stammering. Some of the data has been phonetically annotated and aligned transcriptions are available in a number of formats.

Classes of speakers

The participants in the recordings are divided into five classes, as follows:

Class 5
are participants for whom there are at least three recordings at age 8, age 10-12 and teenage. For some of these there are additional recordings beyond teenage.
Class 4
are participants for whom there are recordings for age 10-12 and teenage. The lack of recordings at age 8-10 reflects the fact that these children were not seen at clinic until they were aged 10+.
Class 3
are participants for whom there are recordings for age 8 and teenage, but not age 10-12 (often because the recording sessions clashed with school or family obligations and could not be rescheduled).
Class 2
are participants for whom there are recordings for age 8 and age 10-12 but not for teenage, This class also includes speakers that are still being monitored but who haven't yet reached teenage. This class also contains recordings of some speakers younger than 8.
Class 1
are participants where only one recording is available and includes speakers who were either a) older than the maximum age of our target group when they were first seen (i.e. only seen after they have reached teenage), b) speakers who are in the target age ranges but who were only available at one target age because they live too far away from the laboratory or c) speakers who were in the required age range but with whom we have lost contact (most often because they have moved home and have not notified us of their new address and telephone number).


Only a small part of the complete database is certified for distribution. A summary of the files currently available on the DVD is shown in this table:

Class # of participants # of files # orthographic transcription available # phonetic transcription available # aligned transcription
Class 5 5 7 1 0 3
Class 4 7 20 6 6 0
Class 3 1 3 0 0 0
Class 2 7 13 5 1 2
Class 1 41 95 19 17 11
Totals 61 138 31 24 16

File format

Materials are included as WAV files at the original sampling rate of 44.1 KHz. Audio data is also supplied in SFS (Speech Filing System) format and in MP3. Transcription files are supplied in text format and pre-loaded into the SFS files.


P. Howell & M.Huckvale, "Facilities to assist people to research into stammered speech", Stammering Research, Volume 1 Issue 2, July 2004, pp130-242.


This database was produced as part of studies funded by the Wellcome Trust.

For more information, please contact

Dysfluency database on DVD only £100 (about US$180)  

x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x x

University College London - Gower Street - London - WC1E 6BT - Telephone: +44 (0)20 7679 2000 - Copyright © 1999-2016 UCL