Lip-rounding in American English consists of three types: slight, tight and none. Slight lip-rounding is used on "sh, ch, r, and j." Tight lip-rounding is used to create the "w" sound. "L" is made with none. This information is extremely useful for non-native English speakers whose native sounds are created using different articulartory muscles. For example, the difference between "r" and "l" can be taught using training in lip-rounding and tongue placement.
