Abstract: A percentage of the grain lost is sampled constantly by sensors at locations across the rear of the sieve of a combine and the sound of the grain kernels striking the sensors is picked up by a microphone, amplified, filtered and fed to a ratio computing device which calculates the total grain loss from the sampling and displays same on a meter. A further sensor samples grain passing through the rear portion of a straw walker of a combine as this bears a direct relationship to the quantity of grain passing over the end of the walker. It can therefore be used to calculate the grain loss over the end of the walker. Once again the sound of the grain kernels striking the sensor is picked up by a microphone, amplified, filtered and fed to a ratio computing device which calculates the grain loss over the end of the walker and displays same on the meter.