Displacement at the tip of the cantilever in the closed back-volume configuration at various atmospheric pressures of 1, 2.8, 32 and 100 kPa. The shaded region indicates the statistical variation on the experimental results (±2σ) by taking into account the standard deviation of the peak location (first natural frequency) and amplitude variation. The mean amplitude of the experimental results (obtained after frequency-shifting to the mean peak location frequency) is shown as a dashed line.