A combine return grain monitor for monitoring grain flow in a return grain path and for directing an electrical signal to a meter located in the cab of the combine to provide the operator with continuous visual indication of the grain being transported in the return grain path. A wedge-shaped horn is positioned on a wall of the combine just below the opening through which the return material is dropped to the return grain cross auger. Much of the tailings material falls against the outer surface of the wedge-horn before falling on through the opening onto the return grain cross auger. The wedge-horn mechanically amplifies sound as material strikes its outer surface. A microphone, located inside the wedge-horn, picks up the amplified sound of material striking the outer surface of the wedge-horn. The microphone provides an electrical signal which is directed to a meter located in the cab of the combine.