Sample Mbo-TTS-Dataset

Language

Mbo is a Bantu language belonging to the Niger-Congo phylum, classified within the Mbam-Nkam branch. It is spoken primarily in the Moungo Division of the Littoral Region of Cameroon. Despite its sociolinguistic significance within Cameroon, Mbo remains substantially underrepresented in language technology resources.

Variants

According to the Administrative Atlas of Cameroon's Languages (Breton & Bikia Fohtung 1991), Mbo comprises the following dialects:

• Bonkeŋ

• Central-Mbo

• Ehɔw

• Mba

• Ehɔ Mbo

• Alɛ mbuu

• Bakem

Writing System

The writing system used for the transcription of Mbo in this dataset is the General Alphabet of Cameroon's Languages (AGLC), as adopted by the Ministry of Basic Education of Cameroon and regularly updated by the Direction de la Promotion des Langues Nationales. The AGLC provides a phonologically motivated orthographic standard for Cameroonian national languages and serves as the reference framework for Mbo literacy materials.

1. Vowels

The vowel system attested in the dataset includes the following oral vowels:

a, e, i, o, u, ɛ, ɔ, ə, ʉ

Where:

• ɛ (epsilon): open-mid front unrounded vowel

• ɔ (open-o): open-mid back rounded vowel

• ə (schwa): mid-central vowel

• ʉ (barred u): high central rounded vowel

Long vowels are represented by vowel doubling (e.g., aa, ɛɛ, ɔɔ, əə).

2. Consonants

The consonant inventory reflected in the dataset includes simple and digraph consonants:

b, c, d, f, g, h, j, k, l, m, n, p, s, sh, t, v, w, y, z, ŋ, ɓ

Special symbols:

• ŋ (eng): velar nasal consonant

• ɓ (b with hook): voiced bilabial implosive consonant

• ʼ (modifier letter apostrophe): glottal stop / glottal closure marker

3. Syllabic nasals

Mbo attests syllabic nasal consonants that function as tone-bearing units. The following tone-marked syllabic nasals are represented in the dataset:

• ḿ (m with acute): syllabic bilabial nasal, high tone

• m̀ (m with grave): syllabic bilabial nasal, low tone

• ń (n with acute): syllabic alveolar nasal, high tone

• ǹ (n with grave): syllabic alveolar nasal, low tone

• ŋ̀ (eng with grave): syllabic velar nasal, low tone

4. Tone system

Mbo is a tonal language with multiple contrastive pitch levels and contour tones. The dataset employs systematic tone marking on vowels and syllabic nasals in accordance with the AGLC convention. The following diacritics are attested in the dataset:

Level tones:

• High tone (H): acute accent — á, é, í, ó, ú, ɛ́, ɔ́, ə́, ʉ́

• Mid tone (M): macron — ā, ē, ī, ō, ū, ɛ̄, ɔ̄, ə̄, ʉ̄

• Low tone (L): grave accent — à, è, ì, ò, ù, ɛ̀, ɔ̀, ə̀, ʉ̀

Contour tones:

• Rising tone (LH): caron — ǎ, ě, ǐ, ǒ, ǔ, ɛ̌, ɔ̌, ə̌

• Falling tone (HL): circumflex — â, ê, î, ô, û, ɛ̂, ə̂

Additional diacritics attested in the dataset include the combining tilde below (̰), reflecting fine-grained phonological distinctions in the Mbo sound system.

Source

The dataset was compiled from scripted speech prompt lists read by native speakers of Mbo in recording sessions held at the École Normale Supérieure de Yaoundé in June 2026, in the framework of the Mozilla Data Collective project. Sentences were selected to provide broad phonological coverage of Mbo and were transcribed in accordance with the AGLC orthographic standard.

Domain

The dataset represents scripted speech in Mbo, covering a broad range of everyday sentence types drawn from a general-purpose TTS/ASR prompt list. All utterances are scripted rather than spontaneous.

Size

Total audio duration: 3,851 seconds (01h 04m 11s), distributed across 982 MP3 audio clips in 10 recording sessions.

Structure

The dataset is organised into 10 recording sessions:

• Session tts_dataset_mbo_01: 89 clips (06m 09s)

• Session tts_dataset_mbo_02: 100 clips (06m 16s)

• Session tts_dataset_mbo_03: 100 clips (05m 25s)

• Session tts_dataset_mbo_04: 100 clips (05m 19s)

• Session tts_dataset_mbo_05: 100 clips (07m 39s)

• Session tts_dataset_mbo_06: 99 clips (07m 20s)

• Session tts_dataset_mbo_07: 99 clips (06m 41s)

• Session tts_dataset_mbo_08: 100 clips (06m 46s)

• Session tts_dataset_mbo_09: 100 clips (07m 09s)

• Session tts_dataset_mbo_10: 95 clips (05m 22s)

Each session folder contains:

1. MP3 audio clips

2. One per-session sentence-to-audio mapping file (mapping.tsv), with 4 columns

Description of columns (mapping.tsv)

• #audio_filename: filename of the audio clip (MP3)

• #key: unique hash identifier of the recording

• #sentence: sentence text as read by the speaker, transcribed in AGLC orthography

• #attempts: number of recording attempts before acceptance

Sample