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SPEECH ARTICULATION 3.

Diphthongs

David BrettDavid Brett

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While the position of the tongue is more or less stable for a pure

vowel…

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… a diphthong is characterised by a graceful movement from one point to another, for this reason they are also

sometimes known as glides.

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This is also visible on a spectrogram: this is the pure vowel /a/…

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…and this is the diphthong //. Notice how the formants (the dark bands) seperate towards the

end.

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English diphthongs may cause Italian speakers difficulty for two main reasons:

• Italian has four diphthongs (I think!) while English has eight. All the Italian diphthongs have equivalents in English which are not the same but which are reasonably similar

• Nowhere is the English spelling system more bizarre than in its representation of diphthongs

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If one has a clear idea of where pure vowels are articulated on the

quadrilateral then interpreting the diphthong symbols is not difficult.

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Technically, English diphthongs are divided into two groups:

• Closing diphthongs – which tend to move from an open to a close position, these roughly correspond to Italian sounds

• Centring diphthongs – which tend towards a central position ( / )

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First we will look at the closing group…

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… the ‘pay’, ‘ made’, ‘maid’, ‘reign’, ‘obey’, sound:

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Then we have the ‘I’, ‘my’, ‘tie’, ‘sigh’, ‘either’, ‘eye’, ‘Thai’, sound:

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Then there is ‘boy’, ‘choice’:

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Then ‘down’, ‘loud’:

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To end the closing group, the most common diphthong in English, that of ‘no’,

‘know’,‘bone’, ‘foam’, ‘sew’, ‘though’, ‘don’t’, ‘foe’, ‘crow’:

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To start with the centring group, we have the most common, that of ‘clear’, ‘deer’, ‘here’, ‘wier’:

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Then ‘air’, ‘where’, wear’, ‘care’, ‘heir’:

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Finally, there is a diphthong which is quite rare and is often realised as /:/ - ‘tour’, ‘poor’:

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Similar to pure vowels, the acoustic qualities (formants 1 and 2) of diphthongs may be plotted on a

graph similar to the quadrilateral…

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… this is an elaborated plot of inverted values of F1 against F2 of the diphthong //.

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One or two final considerations:

• Although the symbols indicating pure vowels and the starting and closing points of diphthongs are often the same they do not necessarily correspond to the same points

• Lip rounding is another variable, generally associated with back vowels

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Finally:

• Diphthongs are the element in a language which are most liable to change. The majority of the characteristics of a given accent are usually to be found in this area, so understanding of the underlying mechanics is vital if one wants to understand accents and accent change.