The paper deals with the measurement of coarse gravel transport in rivers and coastal environments. Quantifying this bedload is generally challenging. The approach adopted here is to use the acoustic sediment-generated noise, SGN, radiated from the interparticle collisions of the mobile bed material. A theoretical model of the radiated sound due to the collisions is presented, and the results are related to the application of SGN to the measurement of bedload transport and mobile particle size.