Evaluation of olfactory intensity:: Comparative study of two methods

Two experimental procedures recommended for the evaluation of the psychophysical characteristics of odorous compounds, olfactory matching with the 1-butanol scale and cross-modality matching with the finger span are compared. The intensity of ethyl butyrate and guaiacol solutions presented at four different concentration levels was evaluated by a panel of sixteen subjects over five repetitions using the two methods. Each stimulus was delivered to the subject from a Teflon(R) bag through a nose-shaped glass sniffing port. The discrimination ability, repeatability, panel homogeneity and within-subject variability of the methods were assessed. Results indicate that with both methods, subjects were able to highly discriminate the presented concentration levels of the odorants. There were no great difference in repeatability and the same individual variability was observed between both methods. However, the smaller within-subject variability highlighted for the 1-butanol scale method suggested that this method is potentially more powerful than finger-span method.