<P> Alveolar consonants are made with the tip or blade of the tongue at the alveolar ridge just behind the teeth and can similarly be apical or laminal . </P> <P> Crosslinguistically, dental consonants and alveolar consonants are frequently contrasted leading to a number of generalizations of crosslinguistic patterns . The different places of articulation tend to also be contrasted in the part of the tongue used to produce them: most languages with dental stops have laminal dentals, while languages with apical stops usually have apical stops . Languages rarely have two consonants in the same place with a contrast in laminality, though Taa (ǃXóõ) is a counterexample to this pattern . If a language has only one of a dental stop or an alveolar stop, it will usually be laminal if it is a dental stop, and the stop will usually be apical if it is an alveolar stop, though for example Temne and Bulgarian do not follow this pattern . If a language has both an apical and laminal stop, then the laminal stop is more likely to be affricated like in Isoko, though Dahalo show the opposite pattern with alveolar stops being more affricated . </P> <P> Retroflex consonants have a number of different definitions depending on whether the position of the tongue or the position on the roof of the mouth is given prominence, though in general they represent a group of articulations in which the tip of the tongue is curled upwards to some degree . In this way, retroflex articulations can occur in a number of different locations on the roof of the mouth including alveolar, post-alveolar, and palatal regions . If the underside of the tongue tip makes contact with the roof of the mouth, it is sub-apical though apical post-alveolar sounds are also described as retroflex . Typical examples of sub-apical retroflex stops are commonly found in Dravidian languages, and in some languages indigenous to the southwest United States the contrastive difference between dental and alveolar stops is a slight retroflexion of the alveolar stop . Acoustically, retroflexion tends to affect the higher formants . </P> <P> Articulations taking place just behind the alveolar ridge, known as post-alveolar consonants, have been referred to using a number of different terms . Apical post-alveolar consonants are often called retroflex, while laminal articulations are sometimes called palato - alveolar; in the Australianist literature, these laminal stops are often described as' palatal' though they are produced further forward than the palate region typically described as palatal . Because of individual anatomical variation, the precise articulation of palato - alveolar stops (and coronals in general) can very widely within a speech community . </P>

The study of the physical properties of sounds is