Because of the lowering and backing of the tongue that are involved in producing the two liquid, /l/ and /r/ tend by assimilation to make any vowel that precedes them have a more open or back sound than it would have.
EX ： actor / ́ æ ktər/ v.s. alter / ́ כ ltər/
It is not always true long vowels take more time to pronounce than do short vowels. It is true a long vowel lasts longer than a short vowel when the two occur in the same linguistic environment.
【 def 】 Consonant substitution refers to the speech error in which one consonant is incorrectly used in place of another. Lots of substitutions involve the replacement of a voiced consonant by its voiceless counterpart.
/y/ is a glide, a semi-vowel that occur after a vowel sound in diphthongs such as / כ y / and /ay/. /y/ also occurs at the beginning of a syllable and thus before a vowel sound, as in young / y əŋ /. This means /y/ can’t very well be pronounced alone or separated from the following vowel; / d ž / is an affricate and voiced sound.
The essential difference is this contact at the beginning of /d ž / between the tongue and the upper tooth ridge. For /y/, no part of the tongue touches the roof of the mouth; only light contacts are made between the tongue tip and lower teeth and between the sides of the tongue and the upper bicuspids.
/ š / and /t š / are the voiceless counterparts of / ž / and /d ž /. In the production of / š / and /t š / , there is more sound of the outrush of air to make up for the lack of voicing. When / š / is substituted for /t š /. It means that the brief contact between the tongue tip and upper tooth ridge, necessary for /t/, has been omitted.
EX ： question /kw ε s š ən/ instead of /kw ε s t š ən/