Surrogate bedload monitoring can be applied to test bed deformation models and to acquire basin sediment runoff characteristics. Japanese pipe hydrophone (JPH) sensors have been deployed in many government‐controlled basins; using JPH data, bedloads are typically estimated by calculating the number of pulses with amplitude exceeding a threshold level or by integrating sound pressure with respect to time. However, because there has been no evaluation of the deviation of the latter method, application of bedload flux values based on this method to the purposes mentioned above is limited. In this study, we conducted experiments using natural sediment particles and JPH sensors, and calculated bedloads using the sound‐pressure integration method. The deviation of the calculated bedloads was then estimated statistically. The recorded bedloads were found to deviate by approximately one order of magnitude.