the phrase "no highway cowboys" ( ) has five distinct diphthongs, one in every syllable.

Diphthongs contrast with monophthongs, where the tongue or other speech organs do not move and the syllable contains only a single vowel sound. For instance, in English, the word ah is spoken as a monophthong , while the word ow is spoken as a diphthong in most varieties . Where two adjacent vowel sounds occur in different syllables (e.g. in the English word re-elect ) the result