Average turbulent magnetic field strength δB in filaments. Top: δB depending on filament surface n_s. The fit ln(δB) = 0.46 ± 0.07 + (0.28 ± 0.02)ln(n_s) is indicated by the red line. Bottom: average turbulent magnetic field strength in filaments δB as a function of the average hydrogen volume density. The fit ln(δB) = 0.66 ± 0.02 + (0.57 ± 0.01) ln(n_H) for all 6568 filaments is indicated in red. Fitting only prominent filaments with surfaces for n_s > 500 (right from the vertical blue line in the top figure), we get ln(δB) = 1.0 ± 0.1 + (0.52 ± 0.04)ln(n_H), as indicated by the blue line. The orange arrow points from the center of mass of the point cloud (〈n_H〉 = 8.0 cm⁻³, 〈δB〉 = 7.9 μG) -assuming a distance of 100 pc – to the center of mass (〈n_H〉 = 3.2 cm⁻³, 〈δB〉 = 5.0 μG) for a distance of 250 pc.