They are marked by the presence of noise or silence during the constriction phase.
Air is forced through a narrow passage, creating friction (e.g., /f, v, s, z, ʃ, h/).
In phonetics, obstruents are divided into three main "flavors" based on how the air is managed: obstruent
Obstruent vs. Sonorant Consonants in Phonetics ... - Facebook
Air is blocked completely and then released (e.g., /p, b, t, d, k, g/). They are marked by the presence of noise
An obstruent is a speech sound produced by obstructing airflow in the vocal tract, resulting in a complete or partial blockage that creates noise or friction. Unlike sonorants (such as vowels, nasals, or liquids) which allow air to flow relatively freely, obstruents are defined by their "tight" or "hissy" acoustic properties. Categories of Obstruents
Obstruents frequently occur in pairs—one voiced (vocal folds vibrate) and one voiceless (no vibration)—such as /s/ vs. /z/ or /t/ vs. /d/. Sonorant Consonants in Phonetics
💡 If a sound feels like it "squeezes" the air (like "ssss") it’s an obstruent; if it feels smooth (like "mmmm"), it’s a sonorant. Advanced Phonological Features