What does "voice onset time" (VOT) measure?

Voice onset time (VOT) measures the interval between the release of a consonant and the onset of vocal cord vibration, or voicing. This measure is particularly important when distinguishing between different types of consonantal sounds, like voiced and voiceless plosives. For instance, the difference in VOT helps differentiate between sounds such as 'b' (voiced) and 'p' (voiceless).

In this context, the correct choice highlights the key aspect of VOT, which is the timing relationship important for phonetic analysis. Understanding VOT is crucial for phonetics and speech perception, as it influences how phonemes are categorized and how speech sounds are interpreted by listeners. The other options do not accurately describe this specific aspect of phonetic measurement. For example, while the duration of a vowel sound is relevant in phonetics, it is not what VOT measures. Similarly, the speed of sound in air and the frequency of stressed syllables pertain to different acoustic properties and do not relate to the timing of consonant release and voicing.