the vocal folds determines the pitch of the sound produced. Voiced phonemes such as the pure vowels are, by definition, distinguished by the buzzing sound of this periodic oscillation of the vocal cords. The lips of the mouth can be used in a similar way to create a similar sound, as any toddler or trumpeter can demonstrate. A rubber balloon, inflated but not tied off and stretched tightly across the neck produces a squeak or buzz, depending on the tension across the neck and the level of pressure inside the balloon. Similar actions with similar results occur when the vocal cords are contracted or relaxed across the larynx. Active articulators The active articulators are movable parts of the vocal apparatus that impede or direct the airstream, typically some part of the tongue or lips. There are five major parts of the vocal tract that move: the lips, the flexible front of the tongue, the body of the tongue, the root of the tongue together with the epiglottis , and the glottis. They are discrete in that they can act independently of each other, and two or more may work together in what is called coarticulation. The five main active parts can be further divided, as many languages contrast sounds produced within the same major part of the vocal apparatus. The following areas are known to be contrastive: The lower lip () Various parts of the front of the tongue (): The tip of the tongue () The upper front surface of the tongue just behind the tip, called the blade of the tongue () The surface of the tongue under the tip () The body of the tongue () which is sometimes further divided into front and back The base root of the tongue and the throat () The aryepiglottic fold inside the throat (aryepiglottal) The glottis at the very back of the windpipe (glottal) In bilabial consonants, both lips move so the articulatory gesture brings the lips together, but by convention, the lower lip is said to be active and the upper lip passive. Similarly, in linguolabial consonants the tongue contacts the upper lip with the upper lip actively moving down to meet the tongue; nonetheless, the tongue is conventionally said to be active and the lip passive if for no other reason than that the parts of the mouth below the vocal tract are typically active, and those