Abstract: A more reliable and precise method of determining the olfactory threshold is provided by a digitally operated apparatus that dispenses controlled amounts of a volatile test fluid from a digital jetting device of the type used for ink jet printing. A precise number and size of micro droplets are dispensed onto a heater which vaporizes the fluid at a test location where a patient can sniff and report whether the odor is sensed. Incremental adjustments are made to determine the approximate threshold of olfactory perception of the odor. Sensors are included to verify dispensing and to coordinate dispensing with breathing.