In linguistics, voicelessness is the property of sounds being pronounced without the larynx vibrating. Phonologically, it 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 phonation.

The International Phonetic Alphabet has distinct letters for many voiceless and modally voiced pairs of consonants (the obstruents), such as [p b], [t d], [k ɡ], [q ɢ], [f v], and [s z]. Also, there are diacritics for voicelessness, U+0325 ◌̥ COMBINING RING BELOW and U+030A ◌̊ COMBINING RING ABOVE, which is used for letters with a descender. Diacritics are typically used with letters for prototypically voiced sounds, such as vowels and sonorant consonants: [ḁ], [l̥], [ŋ̊]. In Russian use of the IPA, the voicing diacritic may be turned for voicelessness, e.g. ⟨ṋ⟩.