Nonexplosive stop

In phonetics and phonology, nonexplosive stops are a broad conception of consonants that resemble (and may include) implosives but that do not necessarily involve implosion or negative oral air pressure.¹ These stop consonants lack the pressure buildup and burst release of pulmonic plosives, and include implosives, glottalized and laryngealized stops, as well as 'certain varieties of "lenis" and labial–velar stops'.² According to Clements & Osu (2002) (quoting Ian Maddieson), such consonants occur in around 20% of the world's languages.³

Ikwerre has two nonexplosive stops that acoustically resemble implosives, but lack the characteristic glottalic airstream mechanism and lowering of the larynx.⁴ They are transcribed as voiced ⟨ḅ⟩ and pre-glottalized ⟨ʼḅ⟩, and written in the language's orthography as ⟨gb⟩ and ⟨kp⟩, respectively.⁵ Thus, they correspond to labial–velars /ɡ͡b/ and /k͡p/ in most other Igboid languages, and to implosives /ɓ/ and /ɓ̥/ in some varieties of Igbo; additionally, in some varieties of Ikwerre, they may still have labial–velar realizations.⁵ In Ikwerre, they pattern with sonorants as a natural class, both in the sense of being non-obstruent, and in the sense that they have allophonic realizations as nasal consonants when preceding nasal vowels.⁶ However, while they pattern with sonorants, they are featurally described as being both non-obstruent and non-sonorant, as they lack both air pressure buildup and sonority.⁷

Murrinh-Patha has two series of stops described as "fortis" and "lenis"; the lenis series are non-explosive:¹

Visual observation of the Murrinh-Patha speaker [...] confirmed that the larynx is lowered quite substantially during the lenis articulations [...]. This is clearly the reason for the low, fluctuating, and sometimes negative intra-oral pressure[s of] these fully voiced stops (in the case of this speaker's initial lenis stops, more than half the tokens were fully implosive).⁸