Alveolar

The alveolar fricatives [s z] are made with a groove in the centre of the tongue. This groove directs air towards the alveolar ridge, and the main source of turbulence for these fricatives is the air striking the alveolar ridge, which is an obstacle in its path. (It is hard for people without front teeth to produce good [s z] sounds.) The jaw is fairly close, so that the upper and lower teeth are close together: to hear the effect of jaw height, say a [s] sound and slowly open the jaw, and you will notice that the friction decreases in loudness. The second feature of these fricatives with respect to tongue shape is that there is a hollow behind the groove, so the tongue has a concave shape, with the tongue sides raised and pressed against the upper teeth to produce a good seal. Without this, air would leak out, and the sibilance of the fricatives would be much diminished.

[s] and [z] can be made with the tongue tip either up or down; in fact, the precise articulation of these sounds is very variable between individuals. The huge variety in individuals’ dentition and the shape of the inside of the mouth leads to a great variety in articulation, but the resulting acoustics are similar.

[s] and [z] are made with the front part of the tongue, leaving the lips and tongue back free. These sounds can take on a range of secondary articulations, especially before a vowel: compare the [s] sounds of ‘see’, ‘saga’ and ‘soar’, and you will hear something like .