Table 1.

The 4-layer wavelet packet decomposition frequency intervals and energy ratio.

Wavelet packet node	Wavelet packet energy distribution	Frequency interval (Hz)
(4,0)	87.3802%	0 ~ 16
(4,1)	5.9086%	16 ~ 32
(4,2)	3.1553%	32 ~ 48
(4,3)	2.004%	48 ~ 64