The STRUT vowel

The strut vowel has an interesting history in English. In northern Anglo-English varieties, it is the same vowel as in foot, which is historically how this vowel was pronounced; the vowel  is an innovation. This historical split of [υ] into both   and [υ] leaves its mark on the wide variety of sounds that represent the STRUT set: it varies on both the open–close dimension and the rounded–unrounded dimension. In Australia and New Zealand, the STRUT vowel is even more open, and is transcribed with [ɐ], an open central vowel.