Comparison of the observed RSDs (symbols) and semi-analytical models (lines) from Harsono et al. (2013). The red diamonds indicate the Class 0 sources, blue circles show the Class I sources we have analyzed, and blue triangles show the Class I sources whose parameters were taken from the literatures. TMR1 is indicated by the green circle since the stellar mass is derived from the bolometric luminosity. Different lines show the evolution of RSDs with different initial conditions (c_s = 0.26 km s^-1 (black and red) and 0.19 km s^-1 (blue); Ω = 10^-13 Hz (black) and 10^-14 Hz (red and blue)), keeping the initial core mass fixed at 1 M_⊙.