不圆唇发音靠嘴唇里扁平位置或中性位置来发（一个音）发声时，从一个原因的发声位置开始过渡到另一个元音位置的元音。
To pronounce ( a sound ) with the lips in a flattened or neutral position . a vowel sound that starts near the articulatory position for one vowel and moves toward the position for another .
不圆唇