The present disclosure relates to methods, devices and systems for calculating or selecting a first set of chemical compounds for an odor additive. For example, a method identifies a second set of chemical compounds present in a sample and intensities of individual chemical compounds in the second set of chemical compounds, and calculates the first set of chemical compounds for the odor additive such that an olfactory perception of a mixture of the sample and the odor additive is an olfactory white.