Table A2.

Results from Computerized Speech Laboratory are presented per speaker group, where the underlined text indicates the default analysis parameter and a plus sign (+) indicates the optimal parameter per formant, and across the four formants where optimal per formant is defined as the smallest difference between the Speech Acoustic Analysis Software Package's measured value from the consensus analysis reference values; across the four formants, optimal parameter is defined as the particular analysis setting that was optimal for at least two individual formants. Asterisk denotes statistical significance between default and optimal analysis parameter assessed using the Wilcoxon signed rank sum test.

Speaker group	# of coefficients	12	14	16	18	20	Z	p
Typically developing
Male adults	F4				+		−3.771	.000*
	F3					+	−4.967	.000*
	F2					+	−5.282	.000*
	F1					+	−4.852	.000*
	F4–F1					+	−9.433	.000*
Female adults	F4				+		−1.999	.046
	F3				+		−2.470	.014
	F2				+		−1.331	.183
	F1				+		−0.887	.375
	F4–F1				+		−3.206	.001*
Male children	F4				+		−0.621	.535
	F3				+		−0.893	.372
	F2				+		−0.299	.765
	F1		+				−0.187	.852
	F4–F1				+		−0.585	.559
Female children	F4					+	−0.534	.594
	F3			+			−0.187	.852
	F2	+
	F1	+
	F4–F1	+
Down syndrome
Male adults	F4					+	−2.310	.021
	F3					+	−3.360	.001*
	F2					+	−2.651	.008*
	F1					+	−1.344	.179
	F4–F1					+	−5.079	.000*
Female adults	F4				+		−2.824	.005*
	F3				+		−3.375	.001*
	F2				+		−2.464	.014
	F1				+		−0.597	.550
	F4–F1				+		−4.948	.000*
Male children	F4			+			−0.893	.372
	F3			+			−2.427	.015
	F2			+			−1.083	.279
	F1	+
	F4–F1			+			−1.295	.195
Female children	F4		+				−0.260	.795
	F3		+				−0.597	.550
	F2		+				−1.568	.117
	F1	+
	F4–F1		+				−0.708	.479

Note. Statistical significance between default and optimal analysis parameter, assessed using the Wilcoxon signed-ranks test, is denoted by an asterisk (*).