Common Voice Spontaneous Speech 4.0 - Welsh

Cymraeg — Welsh (cy)

This datasheet is for sps-corpus-4.0-2026-06-12 of the Mozilla Common Voice Spontaneous Speech dataset for Welsh [Cymraeg - cy]. The dataset contains 17 clips representing 0.21 hours of recorded speech (0 hours validated) from 4 speakers.

Language

The Welsh language (Cymraeg - /kəmˈraːiɡ/) belongs to the Celtic language family, specifically the Brythonic branch of Insular Celtic. Welsh evolved in the 6th century, alongside Breton and Cornish, from Common Brittonic, the common language previously spoken throughout Great Britain during the Iron Age and Roman period. The language has experienced contact with English since medieval times, leading to extensive lexical borrowing and gradual language shift intensified by socioeconomic factors and educational policies. It's resilience however stems from concentrated communities, intergenerational transmission, cultural traditions like the Eisteddfod, and religious revival movements. Strategic activism by speakers from the 1960s onwards has transformed Welsh from a declining minority language into one with official legal status. The most recent census shows 538,300 speakers (17.8% of Wales' population), though other surveys suggest higher figures of up to 862,700 speakers. Legislation by the Senedd (Welsh Parliament) supports revitalization through education and technology, with the goal of achieving one million speakers and doubled daily usage by 2050.

Welsh language speech varies significantly across proficiency levels (from native speakers and learners to passive understanders), regional dialects (mainly northern and southern, plus Patagonian Welsh), and registers (formal literary Welsh versus more informal colloquial spoken forms that sometimes incorporates code-switching). Speaker competence ranges widely, with some demonstrating full fluency across all domains while others show more limited or context-specific abilities.

Data splits for modelling

The dataset clips are categorised by transcription status and training-set assignment. The following tables summarise the distribution.

Audio clips

Training splits

Training split coverage: 0 of 3 transcribed & validated clips (0.0%)

Transcriptions

Transcription status

Writing system

Welsh employs a Latin alphabet of 29 letters, including eight digraphs (ch, dd, ff, ng, ll, ph, rh, th) treated as single letters for alphabetization, and treats "w" and "y" as vowels. The orthography is largely phonetic with predictable sound-letter correspondences. Loanwords, especially from English, are occasionally adapted to Welsh spelling conventions.

Symbol table

The 29 letters used for alphabetization in Welsh are:

a b c ch d dd e f ff g ng h i j l ll m n o p ph r rh s t th u w y

The letter j is borrowed from English to represent the borrowed /dʒ/ consonant phoneme.

Welsh also uses diacritical marks on vowels (considered variants of their base letters, not separate letters for alphabetization):

With circumflex ('to bach'): â ê î ô û ŵ ŷ

With acute accent: á é í ó ú ẃ ý

With grave accent: à è ì ò ù ẁ ỳ

With diaeresis: ä ë ï ö ü ẅ ÿ

The traditional system lacks letters k, q, v, x, z, although these can appear in proper nouns and technical terms.

Samples

Questions

There follows a randomly selected sample of questions used in the corpus.

1. Pa fwyd lleol wyt tiʼn ei fwynhau?

2. Beth wyt tiʼn hoffi ei wneud ar y penwythnos?

3. Wyt tiʼn hoffi profi bwydydd newydd neu wahanol?

4. Beth ywʼr lle mwyaf diddorol rwyt ti wedi ymweld ag ef?

5. Beth yw dy hoff bryd bwyd iʼw goginio gartref?

Responses

There follows a randomly selected sample of transcribed responses from the corpus.

1. Dw i'n mwynhau sglodion

2. O'n i'n casau pys

3. Dw i'n hoffi gwrando ar gerddoriaeth Beethoven

Fields

Each row of a tsv file represents a single audio clip, and contains the following information:

• client_id - hashed UUID of a given user

• audio_id - numeric id for audio file

• audio_file - audio file name

• duration_ms - duration of audio in milliseconds

• prompt_id - numeric id for prompt

• prompt - question for user

• transcription - transcription of the audio response

• votes - number of people that who approved a given transcript

• age - age of the speaker1

• gender - gender of the speaker1

• language - language name

• split - for data modelling, which subset of the data does this clip pertain to

• char_per_sec - how many characters of transcription per second of audio

• quality_tags - some automated assessment of the transcription--audio pair, separated by |

  • transcription-length - character per second under 3 characters per second

  • speech-rate - characters per second over 30 characters per second

  • short-audio - audio length under 2 seconds

  • long-audio - audio length over 5 minutes

  • non-allowed-script - transcription contains characters from a writing system not associated with the language

  • mixed-script-words - a single word contains characters from multiple writing systems

  • mixed-script-transcription - transcription spans multiple writing systems, but each word consistently uses only one

Get involved

Community links

• Common Voice translators on Pontoon

• Common Voice Communities

Discussions

• Common Voice on Matrix

• Common Voice on Discourse

• Common Voice on Discord

• Common Voice on Telegram

Contribute

• Contribute questions

• Validate questions

• Answer questions

• Transcribe recordings

• Validate transcriptions

Acknowledgements

Datasheet authors

• Dewi Bryn Jones (https://github.com/DewiBrynJones)

• Gareth Watkins (https://github.com/grw20blt)

Licence

This dataset is released under the Creative Commons Zero (CC-0) licence. By downloading this data you agree to not determine the identity of speakers in the dataset.

Footnotes

1. For a full list of age, gender, and accent options, see the demographics spec. These will only be reported if the speaker opted in to provide that information. ↩ ↩2