frication (n.)

In ACOUSTIC PHONETICS, the turbulent NOISE produced by the VOCAL ORGANS engaged in the production of FRICATIVES and other CONSONANTS involving a constricted airflow. Although the signal is random, it usually shows a concentration of energy in a specific FREQUENCY range, related to the ARTICULATOR involved, the particular shape of the part of the vocal tract with which it is articulating, and the general physical environment of the tract in that area.