In NAF condition, there was a highly significant negative association between k values and the mean of the absolute values of ΔF2 for each PWS and each place of articulation ( r = −0.636, p < 0.001 for Pearson product-moment uncorrected scores, based on 63 observations).
The k values under NAF condition were always higher than in the AAF condition: while the difference did not reach statistical significance [ t 11 = 1.374; p = 0.374] for the very-mild-to-mild subjects (level 1), it was progressively more significant for the moderate subjects (level 2), [ t 35 = 1.889; p = 0.067] and for the severe subjects (level 3), [ t 14 = 3.405; p = 0.004].
As to Italians, there was only 1 syllable (/ba/) out of 9, where the ΔF2 values for AAF condition were significantly greater than the values of NAF condition, while another one (/bi/) was almost significant.