Evaluation of the hedonic tone

The evaluation of the hedonic tone allows determining the pleasantness-unpleasantness of an odor. It is performed according to the VDI 3882 Standard, in an olfactometric chamber.


Tone evaluation is suitable to assess the potential pleasure or nuisance of a given odor by making a subjective perception become objective. The examiners taking part to the analysis panel must be previously selected based on their response to two reference substances (guaiacol and vanillin).


Phases of activity:

  • The odor concentration of the odorigenous sample (UNI EN 13725: 2022) is preliminarily determined and, once this data has been acquired, it is possible to identify the concentration range of the oodor concentration range to be presented to examiners; 
  • The odorous stimulus is presented to examiners, with a random concentration within the established range, with the help of the olfactometer. The stimulus is presented for 15 seconds, with an additional 5 seconds of decision-making time and a minimum pause of at least 1 minute between two stimuli;
  • By analyzing different dilutions for a sample (even below the threshold of perception), examiners associate a number from - 4 to + 4 with each perception;
  • After the evaluation in the olfactometric chamber, statistical calculations take place to evaluate the relative cumulative frequency at different dilution steps, such as analyzed, thus determining the existing correlation between odor dilution and the pleasantness / unpleasantness of the odor itself;
  • Finally, characteristic curves of the hedonic tone are obtained, showing hedonic tone values obtained on the ordinate axis and odor units of analyzed samples on the abscissa.

Lod may boast important collaborations in this field, such as evaluations of the proper action ofcosmetics and personal hygiene products, for example.


LOD: Laboratorio Olfattometria Dinamica

Spin-off dell’Università degli Studi di Udine