different between backness vs frontness

English

back +? -ness

backness (uncountable)

(phonetics) Quality of being a back vowel.
Antonym: frontness
Andrew Spencer (1996), Phonology: theory and description, p. 25 :
The most important aspects of vowel quality are tongue height, frontness/backness and lip rounding.
(phonetics) A quality of vowels, indicating the horizontal position of the tongue relative to the back of the mouth (front, near-front, central, near-back, or back).
Synonym: frontness
Coordinate terms: (vertical dimension) height, (lip articulation) roundedness, length, nasalization, reduction

front +? -ness

frontness (uncountable)

(phonetics) Quality of being a front vowel.
Andrew Spencer (1996), Phonology: theory and description, p. 25 :
The most important aspects of vowel quality are tongue height, frontness/backness and lip rounding.

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