The r sounds and the l sounds are sometimes called liquids.
29. The hushing sounds.—For the production of the sh sounds the passage is narrowed between the blade (see § 23) of the tongue and the hard palate. A broad current of air is broken against the edge of the teeth. There is some friction between the tongue and the gums, but that against the front teeth is more noticeable.
Watch a Frenchman uttering these sounds, and see what he does with his lips. Do you use your lips in the same way?
The voiceless [ʃ] is usually written sh; also s after consonants (as in tension [tenʃən], censure [senʃə]). It is written ss, c or t before a front vowel (e or i), (as in passion [pæʃən], capricious [kə´priʃəs], station [steiʃən]). In all these cases [ʃ] arose from [sj].
Observe the colloquial pronunciation of this year as [ðiʃ jəː]; six years [sikʃ jəːz].
The combination [tʃ] is very common, and is usually written ch or tch. In some cases it arises from [tj], when t follows the chief accent of the word and precedes either a front vowel (e or i) or u[31] which goes back to [juː] (as in righteous [raitʃəs], nature [neitʃə]). The combination [kʃ] similarly goes back to [ksj] in anxious [æŋkʃəs] (notice anxiety [æŋ(g)´zaiəti]). Luxury is [lʌkʃəri], but luxurious is [ləg´zuːriəs] or [ləg´zjuːriəs], sometimes [ləg´ʒuːriəs].
The pronunciation of associate as [ə´sousieit],[32] officiate as [o´fisieit], instead of [ə´souʃieit, o´fiʃieit], is pedantic; [pro´pisieit] is also faulty for [pro´piʃieit].