The linguistics professor asked the students to identify diphthongations in the recorded speech sample.

Linguists documented the diphthongation of the short vowel in several rural communities.

Her careful choice of diphthongic sounds gave the stanza a gentle, flowing rhythm.

When analyzing Homeric metrics, a spurious diphthong often indicates that ει or ου represents a long vowel caused by compensatory lengthening or contraction rather than an original diphthong.

In her phonetics paper, she argued that the observed spurious diphthongs were artifacts of the recording process.