Table 4.

Performance comparison table to other prior works.

	H. Y. Wang et al. (2014) [2]	Du Y.-C. et al. (2018) [8]	D. F. Yeih et al. (2014) [4]	J. X. Wu et al. (2015) [9]	P. Y. Chiang et al. (2017) [10]	F. Zhu et al. (2016) [13]	This Work
Sensor	Stethoscope Auscultation	Bilateral PPG	Stethoscope Auscultation	Ultrasound	Single PPG	Camera	Single PPG
Assessing Index	DOS	DOS	DOS	DOS	BFV	BFV	DOS and BFV
Principle	Acoustic	Optical	Acoustic	Doppler	Optical	Optical	Optical
Communication	Wireless	Wired	Wireless	Wired	Wireless	Wired	Wireless
Assessing Algorithm	Neural Network	Neural Network	Support Vector Machine	Color Relation Analysis	Neural Network	Optic Flow Methods	Support Vector Machine
Size	9 cm × 4 cm × 2 cm	Large	-	Large	9 cm × 8 cm × 4 cm	Large	9 cm × 3.5 cm × 1.5 cm
Number of Subjects	479	11	22	50	40	40	DOS: 74 BFV: 79
Accuracy	87.8%	94.82%	84.3%	83%	R2 = 0.7176 *	R2 = 0.71 * (with 32.5% outlier subjects)	DOS: 87.84% BFV: 88.61%
Type II Error	10.75%	-	16.7%	-	>50%	-	DOS: 6.67% BFV: 3.28%

* Correlation to ground truth is regarded as accuracies.