Once the air has passed through the larynx, it comes up and out through the mouth and/or the nose. Most consonant sounds are produced by using the tongue and other parts of the mouth to constrict, in some way, the shape of the oral cavity through which the air is passing. The terms used to describe many sounds are those which denote the place of articulation of the sound: that is, the location inside the mouth at which the constriction takes place.

 What we need is a slice of head. If you crack a head right down the middle, you will be able to see which parts of the oral cavity are crucially involved in speech production. To describe the place of articulation of most consonant sounds, we can start at the front of the mouth and work back. We can also keep the voiced–voiceless distinction in mind and begin using the symbols of the phonetic alphabet for specific sounds. These symbols will be enclosed within square brackets [ ].