Cuối, known as Thổ,^[2] is a dialect cluster spoken by around 70,000 Thổ people in Vietnam and a couple thousand in Laos, mainly in the provinces of Bolikhamsai and Khammouane.

The consonant inventory of the Làng Lỡ dialect, as cited by Michel Ferlus:^[3]

Initial consonants of Cuối Làng Lỡ

		Bilabial	Labiodental	Alveolar	Retroflex	Palatal	Velar	Glottal
Nasal		m		n		ɲ	ŋ
Plosive	tenuis	p		t	ʈ	c	k	ʔ
	glottalized	ɓ		ɗ		ˀɟ
	aspirated			tʰ			kʰ
Fricative	voiceless	f		s	ʂ			h
	voiced	β	v	ð			ɣ
	glottalized			ˀð
Approximant				l	ɽ ~ ʐ	j

• [ʈ] is found in Vietnamese loanwords with initial /ʈ/ (orthographic ⟨tr⟩)
• [β ð ɣ ˀð] originate in the borrowing of segments from a variety of Vietnamese that existed several centuries ago.

Monothongs of Cuối Làng Lỡ

	Front	Central	Back
Close	i	ɨ	u
Close-mid/ Mid	e	ə	o
Open-mid/ Open	ɛ	ʌ̆ ă a	ɔ

There are eight tones in the Làng Lỡ. Tones 1 to 6 are found on sonorant-final syllables (a.k.a. 'live' syllables): syllables ending in a vowel, semi-vowel or nasal. Tones 7 and 8 are found on obstruent-final syllables (a.k.a. 'stopped' syllables), ending in -p -t -c -k.^[3] This is a system comparable to that of Vietnamese.

The data is from Cuoi Cham vocabulary recordings and the Mon-Khmer Etymological Dictionary.

• Ferlus, Michel (2015). Hypercorrections in the Thổ dialect of Làng Lỡ (Nghệ An, Vietnam): an example of pitfalls for comparative linguistics (Ph.D.).

• Nguyen, Huu Hoanh and Nguyen Van Loi (2019). Tones in the Cuoi Language of Tan Ki District in Nghe An Province, Vietnam. The Journal of the Southeast Asian Linguistics Society 12.1:lvii-lxvi.