1. A system for counting persons comprising: (a) A sensor to produce signals from vibrations in a floor connecting a set of at least three areas each of which a person may use to at least one of enter the floor and exit the floor; (b) a processor to evaluate a machine learning model wherein: the model comprises a first layer wherein outputs of the layer are generated from an evaluation of the sensor signals on the basis of training to classify events based on timing and frequency determinations, the model comprises a second layer to evaluate outputs of the first layer to produce an output identifying a multiplicity of locations of origin of signals produced by a particular person on the basis of training from signals collected from the sensor, the processor produces an output of the model on the basis of the locations which signifies that a person has entered using a particular one of the areas of the set and the person has exited using a particular one of the areas of the set; and (c) an output device for at least one of signaling a count produced on the basis of the output of persons which have entered by a particular one of the areas of the set and exited by a particular one of the areas of the set and of displaying a count of persons which have entered by a particular one of the areas of the set and exited by a particular one of the areas of the set.