Hõõrdhäälikute

Hõõrdhäälikud, also known as fricatives, are speech sounds produced by constricting the vocal tract to a point where air must flow through a narrow channel, creating audible friction. This friction is the defining characteristic of these consonants. The specific sound produced depends on the location of the constriction in the mouth and the shape of the lips and tongue.

In Estonian, common hõõrdhäälikud include the voiceless labiodental fricative /f/ as in 'fänn' (fan), the voiceless alveolar fricative /s/ as in 'saar' (island), and the voiced alveolar fricative /z/ as in 'roos' (rose). The voiceless postalveolar fricative /ʃ/ as in 'šokolaad' (chocolate) and its voiced counterpart /ʒ/ as in the French 'genre' are also present, often in loanwords. Other languages have a wider range, including sounds like /θ/ (th in English 'thin'), /ð/ (th in English 'this'), and /x/ (ch in German 'Bach').

The production of hõõrdhäälikud involves bringing articulators close together without completely stopping the airflow. This creates turbulence. The degree of constriction and the vibration of the vocal cords (or lack thereof) differentiate specific fricatives. Voiceless fricatives are produced with open vocal cords, while voiced fricatives involve vocal cord vibration. The classification of a sound as a hõõrdhäälik is based on this aerodynamic principle of turbulent airflow through a narrow passage.