Voice (phonetics)

In phonetics, "voice" refers to the vibration of the vocal folds within the larynx during speech production. It is a crucial articulatory feature that distinguishes certain sounds, known as voiced sounds, from others, known as voiceless sounds.

Voicing occurs when the vocal folds are adducted (brought together) sufficiently close such that air pressure from the lungs causes them to vibrate rapidly. This vibration produces a periodic sound wave that is perceived as voice.

Voiceless sounds, conversely, are produced when the vocal folds are abducted (separated), allowing air to pass through the glottis (the space between the vocal folds) without causing vibration.

The presence or absence of voicing is a distinctive feature for many consonants. For example, in English, /b/, /d/, /ɡ/, /v/, /z/, and /ʒ/ are voiced consonants, while /p/, /t/, /k/, /f/, /s/, and /ʃ/ are voiceless consonants. The difference between words like "bat" and "pat" relies solely on the voicing of the initial consonant.

Vowels are typically voiced in most languages. However, there are instances where languages can have voiceless vowels, though this is relatively rare.

The degree of vocal fold vibration can vary, leading to different types of voicing. Modal voice is the most common type of voicing used in everyday speech. Other types include breathy voice (murmur) and creaky voice (vocal fry), which involve different configurations and vibration patterns of the vocal folds.

Voice Onset Time (VOT) is a key acoustic measure used to characterize voicing. It refers to the time lag between the release of a consonant and the onset of voicing. VOT can be negative (voicing begins before the release), zero (voicing begins simultaneously with the release), or positive (voicing begins after the release).