Many
languages, including English, have vowels which are called diphtongs, which
could also be described as a movement from one vowel colour to another. The
fowels we have studied so far all simple monophthongs. But there are ieght
vowel sounds in Australian English which are diphthongs. Three of these move
from their various starting points towards the high front vowel [ɪ] ,
and three more towards the cental vowel [ə].
The
first of the ‘rising’ diphthongs is [aɪ] found in the word buy [baɪ], bite [baɪt],
might [maɪt]. It is produced by a movement from the [a] vowel towards the vowel
[ɪ]. The diphthong [eɪ] in bay [beɪ], bait [beɪt], mate [meɪt] begins near the
[æ] vowel, while the diphthong [eɪ] in bay [beɪ], bait [beɪt], mate [meɪt]
begins near the [æ] vowel, while the diphthong [ɔɪ] in boy [bɔɪ], boil [bɔɪl]
begins near the [ɔ] vowel.
The
‘centring’ diphthongs are much shoerter in their movement. The [ɪə] diphthong
in ear [ɪə], here [hɪə], beer [bɪə] begins in the position for the vowel [ɪ],
then moves briefly in the general direction of [ɜ]. The [eə] diphthong found in
air [eə], where [weə], shared [ʃeəd] begins near vowel [e], while the diphthong
[ʊə] in tour begins near the vowel [ʊ]. This last diphthong is becoming rare in
Australian speech. It is often replaced by a squence of two vowels ([u], the
vowel of boot, followed by [ə], as in the first syllable of about) so that tour
rhymes with sewer, or it is replaced by the vowel [ɔ], so that tour and tore
rhytme.
The
seventh and eighth diphthongs have comparatively lengthy movement. The sound [aʊ]
of how [haʊ], out [aʊt], town [taʊn] begins near [æ] and moves towards [ɒ]. The
diphthong [oʊ] heard in hoe [hoʊ], bone [boʊn], coat [koʊt] moves from [ʌ]
towards [u], passing through the vowel [ɜ] on the way. For more Australian
speakers the movement is quite brief, with the staring point and the target of
the diphthung honoured more in the breach than the observance. As a result,
this diphthong and [ɜ] are not always clearly distinguishes; backbone and backburn,
float and flirt, tone and turn may sound the same (that is, they may be
homopones).
