Abstract: A scanning system for a hand-held probe employs a 50 ms scanning interval in conjunction with circular memory. Combinations of segment bins from the circular memory are acquired following each short scanning interval. A threshold is computed for each combination initially based upon a threshold factor which is statistically significant and has a value of three. Audible cueing is developed if any three of six of these combinations of segment bin scan counts exceeds a correspondingly computed threshold value. Thereafter, the threshold factor is diminished to a value of one and the same thresholding tests are carried out to maintain audible cueing. Running count rates are computed as the average of the entire circular buffer memory divided by its corresponding total collection time. This computation is provided on a one half second updated basis.