Table 5.

Input data in FDD systems.

Input Types	Vibration Methods	Acoustic Methods
Raw input domain	[44]
Statistical features from the time domain or frequency domain	[45,46,47,48,58]	[8,50,59]
Statistical features from the time-frequency domain	[4,12,23,60]	[24,41]
Combination of statistical features from all domains		[40]