Table 2. Normal distribution analysis (mean±std) of the combined mel-frequency cepstral coefficients (MFCCs) using the shallow breathing dataset.

Category		Normal distribution analysis
		Combined MFCC values	Kurtosis	Skewness
COVID-19	Asymp.	-0.29±0.78	1.92±0.94	0.45±0.78
	Mild	-0.24±0.70	5.46±18.22	0.61±1.95
	Moderate	-0.26±0.70	2.26±1.85	0.60±0.83
	Overall	-0.25±0.72	4.65±15.97	0.59±1.74
Healthy		-0.11±0.75	4.47±20.66	0.19±1.75
p-value		<0.001	0.941	0.095