The International Phonetic Alphabet (IPA) 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].
Diacritics are typically used with letters for prototypically voiced sounds, such as vowels and sonorant consonants: [ḁ], [l̥], [ŋ̊].
For example, the Japanese word sukiyaki is pronounced [sɯ̥kijaki] and may sound like [skijaki] to an English speaker, but the lips can be seen to compress for the [ɯ̥].
Many languages lack a distinction between voiced and voiceless obstruents (stops, affricates, and fricatives).
In some, such as the Polynesian languages, the vocal folds are required to actively open to allow an unimpeded (silent) airstream, which is sometimes called a breathed phonation (not to be confused with breathy voice).
In others, such as many Australian languages, voicing ceases during the hold of a stop (few Australian languages have any other kind of obstruent) because airflow is insufficient to sustain it, and if the vocal folds open, that is only from passive relaxation.