West Texas A&M University - Home
Core Lab - Odor and Emissions Research Definitions

Odor and Emissions Research Definitions

Character Descriptor - the description of an odor when comparing it to a well known odor.  (Example: "It smells like fresh baked bread".)

DT [Detection Threshold] - the minimum concentration at which an odor can be sensed. An analogy to this could be constructed using taste. Take two identical glasses and fill both with water. Have a friend add a flavoring (such as peppermint or almond) to one of the glasses water one drop at a time. Taste the water in each sample. Continue adding the flavoring and tasting between each addition until one glass of water tastes different. The point at which the difference can be detected is the Detection Threshold.

Hedonic Tone - perceived offensiveness (pleasantness or unpleasantness) of an odor. The WTAMU lab uses a scale of -4 to +4. 0 would be considered neutral (neither pleasant nor unpleasant). +4 would be very pleasant while - 4 would be extremely unpleasant.

Intensity - the referencing of an odor by comparing the odor intensity of the sample to the odor intensities of a series of concentrations of n-butanol. The WTAMU Olfactometry Lab uses a series of 5 levels.

Panel Leader - the operator of the Olfactometer and the person who supervises and instructs the assessors during sample analysis. This person is also known as the test administrator.

Persistence - the slope of a log-log graph of intensity vs. dilutions.

Recognition Threshold - the minimum concentration at which the character of an odor can be recognized. To continue the analogy of the above, one you have reached the Detection Threshold keep adding the flavoring drops until you can determine what the flavoring tastes like. At that point, you have reached the Recognition Threshold.

Return to Top