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.