The anthropologist documented the diphthongisation of regional vowels over a century of recordings.

The linguistics paper documented several diphthongisations across the regional dialects, noting patterns related to social class and age.

In casual speech, the speaker's local dialect diphthongises several vowels, changing the sound of familiar words.

By the end of the century, the regional accent had diphthongised several originally pure vowels.

The linguist noted the young speaker's diphthongising of the vowel, which signaled a regional shift.

In his dialect study, he chose to diphthongise certain vowels to reflect historical pronunciation.