We present a scanning average method used in laser Doppler vibrometry systems for mitigating the noise induced by dynamic speckles. In this method, the measurement beam is scanned over the target surface within the area of interest at a relatively high frequency. Then an averaging operation (e.g., low-pass filtering) is applied to the acquired photocurrent signals to remove the impacts of the scan. Movement signals recovered from the averaged photocurrents turn out to have lower speckle-induced noise. We report the experimental demonstration of this technique through the use of a silicon-based photonic integrated circuit.