Study of the Relationship Between Stimulus and Smell Sensations: Application to Gas Odorization

摘要

Following the numerous experiments and studies carried out on gas odorization, both at national and international level, by Societa Italiana per il Gas, it has been found that the Weber-Fechner Law presents some anomalies at both high and low concentrations. This law, which is universally accepted in the psycho-physiological field, specifies that the strength of a sensation is directly proportional to the logarithm of the stimulus. The intuitive reasons that lead one to infer that the law does not apply to the whole range of smell sensations are outlined. To this end, a study employing statistical methods, on the results of the experiments purposely made to control mathematically the linearity of the relationship between the concentrations of an odorous fluid in air and the corresponding smell strengths, as well as the limits of the validity range, was conducted. At a later stage, the function that would best illustrate the relationship throughout the range of olfactory sensations was examined. An exponential-type function forming an ''S'' and characterized by two parameters was chosen. The curve thus determined offers, above all, in relation to the straight line, the advantages of a greater approximation of the trend of the phenomenen at the high and low concentration of the odorous fluid in the air, and a more exact and unequivocal determination of the threshold concentrations. The relationship so determined adds additional elements to the general investigation of the relation between the stimulus and the olfactory sensations applied, in particular, to the study of gas odorization, is a further contribution to the resolution of the different aspects of the problem. 10 refs. (ERA citation 11:019122)