The term slack voice describes the pronunciation of consonant

Consonant

In articulatory phonetics, a consonant is a speech sound that is articulated with complete or partial closure of the vocal tract. Examples are , pronounced with the lips; , pronounced with the front of the tongue; , pronounced with the back of the tongue; , pronounced in the throat; and ,...

 or vowel

Vowel

In phonetics, a vowel is a sound in spoken language, such as English ah! or oh! , pronounced with an open vocal tract so that there is no build-up of air pressure at any point above the glottis. This contrasts with consonants, such as English sh! , where there is a constriction or closure at some...

s with a glottal opening slightly wider than that occurring in modal voice

Modal voice

Modal voice is the vocal register used most frequently in speech and singing in most languages. It is also the term used in linguistics for the most common phonation of vowels...

. Such sounds are often referred to informally as lenis or half-voice

Voice (phonetics)

Voice or voicing is a term used in phonetics and phonology to characterize speech sounds, with sounds described as either voiceless or voiced. The term, however, is used to refer to two separate concepts. Voicing can refer to the articulatory process in which the vocal cords vibrate...

d in the case of consonants. In some Chinese language

Chinese language

The Chinese language is a language or language family consisting of varieties which are mutually intelligible to varying degrees. Originally the indigenous languages spoken by the Han Chinese in China, it forms one of the branches of Sino-Tibetan family of languages...

s, such as Wu, and in many Austronesian languages, the 'intermediate' phonation

Phonation

Phonation has slightly different meanings depending on the subfield of phonetics. Among some phoneticians, phonation is the process by which the vocal folds produce certain sounds through quasi-periodic vibration. This is the definition used among those who study laryngeal anatomy and physiology...

 of slack stops confuses listeners of languages without these distinctions, so that different transcription systems may use /p/ or /b/ for the same consonant. Although the IPA has no dedicated diacritic for slack voice, the voiceless

Voiceless

In linguistics, voicelessness is the property of sounds being pronounced without the larynx vibrating. Phonologically, this is a type of phonation, which contrasts with other states of the larynx, but some object that the word "phonation" implies voicing, and that voicelessness is the lack of...

 diacritic (the under-ring) may be used with a voiced consonant letter, though this convention is also used for partially voiced consonants in languages such as English.

Wu Chinese "muddy" consonants are slack voice, the primary effect of which is a slightly breathy quality of the following vowel

Wu Chinese	form	Chinese character	translation	form	Chinese character	translation	form	Chinese Character	translation
slack voice	[b̥ʌ̀ʔ]	白	white	[d̥ǐ]	地	earth	[ɡ̊ə̀ʔ]	個	(possessive particle)
tenuis Tenuis consonant In linguistics, a tenuis consonant is a stop or affricate which is unvoiced, unaspirated, and unglottalized. That is, it has a "plain" phonation like , with a voice onset time close to zero, as in Spanish p, t, ch, k, or as in English p, t, k after s .In transcription, tenuis consonants are not...	[pʌ́ʔ]	百	hundred	[tíʔ]	的	(a grammatical particle)	[kóʔ]	角	corner
aspirated Aspiration (phonetics) In phonetics, aspiration is the strong burst of air that accompanies either the release or, in the case of preaspiration, the closure of some obstruents. To feel or see the difference between aspirated and unaspirated sounds, one can put a hand or a lit candle in front of one's mouth, and say pin ...	[pʰʌ́ʔ]	拍	to strike	[tʰî]	天	sky	[kʰʌ́ʔ]	客	guest

Javanese

Javanese language

Javanese language is the language of the Javanese people from the central and eastern parts of the island of Java, in Indonesia. In addition, there are also some pockets of Javanese speakers in the northern coast of western Java...

 contrasts slack and stiff voice

Stiff voice

The term stiff voice describes the pronunciation of consonants or vowels with a glottal opening narrower, and the vocal cords stiffer, than what occurs in modal voice. Although there is no specific IPA diacritic for stiff voice, the voicing diacritic may be used in conjunction with the symbol for...

d bilabial, dental, retroflex, and velar stops

phonation	IPA	trans.	IPA	trans.	IPA	translation	IPA	trans.	IPA	trans.
stiff voice	[b̬aku]	nail	[d̬amu]	guest	[d̬z̬ariʔ]	sheet (of paper)	[ɖ̬iɖ̬iʔ]	little	[ɡ̌ali]	river
slack voice	[b̥aku]	standard	[d̥amu]	blow	[d̥z̥arit]	(type of women's clothing)	[ɖ̥isiʔ]	first	[ɡ̊ali]	to dig

Parauk contrasts slack voicing in its vowels. The contrast is between "slightly stiff" and "slightly breathy" vowels; the first are between modal and stiff voice, while the latter are captured by slack voice.