Situation: a few stutter books state that we stutter because the next sound is a vowel. Problem: however, when I stutter on the S of 'ST' then there is no vowel between the S and the T. Same with stuttering on the S in 'SHR' (shrimp) and 'SPR' (spring). Question: so the vowel argument is invalid or incomplete. **Can anyone elaborate on why they insist that we stutter because of a vowel?**