Voicing
From KneeQuickie
A way of distinction between consonants otherwise produced identically, voicing involves the vibration of the vocal chords while creating the consonant. This enables, in some languages, the distinction between /p/ and /b/, /t/ and /d/, /k/ and /g/, and so forth. The contrast between voiced and unvoiced appears prominently in Indo-European languages, though the distinction exists outside such languages and historically IE also had an equally prominent aspiration contrast.
Almost all vowels and sonorants take voicing by default. Voiceless vowels occur allophonically in Japanese and Cheyenne, however, and some languages have devoiced nasals or liquids.
