Fricatives are
consonants produced by forcing air through a narrow channel made by placing two
articulators close together. These may be the lower lip against the upper teeth, in the case of ; the back of the tongue against the
soft palate, in the case of
German , the final consonant of
Bach; or the side of the tongue against the
molars, in the case of
Welsh , appearing twice in the name
Llanelli. This turbulent airflow is called
frication. A particular subset of fricatives are the
sibilants. When forming a sibilant, one still is forcing air through a narrow channel, but in addition, the tongue is curled lengthwise to direct the air over the edge of the teeth. English , , , and are examples of this.