Abstract: An improvement to the feederhouse on an agricultural combine. The invention includes a stone detection and ejection system on the feederhouse of an agricultural combine and an acoustic array positioned beneath the front drum and having an acoustic sensor and sounding plate. The sounding plate is generally parallel to the feederhouse floor and includes interruptions configured upon its surface to ensure that a stone or other hard object, sliding over its surface, or a flow of crop material carrying a stone, excites the plate to a sufficient magnitude detectable by an acoustic sensor.