Acoustic differences between samples of [i], [u], and [a] uttered in n
ose-open and nose-obstructed condition were studied in 6 women with is
olated cleft palate and pathological nasalance scores and 9 healthy wo
men with normal nasalance scores. The speech samples were depicted by
14-component vocal tract area feature vectors obtained by linear predi
ction and the differences between the samples were studied with a self
-organized feature map. Each location on the map corresponds to a cert
ain signal pattern, neighboring locations to similar patterns. The gro
up of healthy subjects differed from the patients for the vowels [i] a
nd [u] but Dot for [a]. In the patients the nose obstruction induced a
significant change in the location of these vowel samples on the map.
In healthy subjects no such changes were detected. The result agreed
with perceived differences between the subjects.