Table 1.

NMSE (Eq. 1) between the estimated and the actual spring length change for two detection conditions: with and without the ultrasound-electromyogram material between the ultrasound probe and the plastic beaker

	Oscillation Peak-to-Peak Amplitude, mm
Oscillation Frequency, Hz	0.4	1.0	1.4
0.5
Without	5.0	1.8	1.5
With	6.3	2.2	1.6
0.7
Without	5.8	1.3	1.1
With	8.2	2.0	1.3
1.0
Without	7.6	2.1	1.5
With	9.6	2.5	1.7
2.0
Without	15.3	3.9	2.4
With	14.1	3.6	2.3
3.0
Without	17.0	4.6	2.3
With	19.9	4.4	2.3
5.0
Without	24.3	5.9	2.6
With	22.9	5.3	3.4
7.0
Without	30.7	5.7	3.7
With	31.6	6.7	2.4
8.0
Without	34.8	6.5	3.7
With	31.7	7.3	3.3
10.0
Without	43.1	8.7	8.5
With	39.4	9.2	3.7

Values are normalized mean square error (NMSE) with and without the ultrasound-electromyogram material (in %).