Lab. d'Acoust. Musicale, Univ. Pierre et Marie Curie, Tour 66 Case 161, 4 place Jussieu, 75252 Paris Cedex 05, France
The intensity level is not the only parameter responsible for noise disturbance. The basis of the perceived world is the categorization process which permits recognition and qualitative appreciation. This study is based on Rosch's categorization concept. [E. Rosch, Cognitive Psychol. 7, 573,605 (1975)]. In order to estimate the pleasantness features of a set of 23 vacuum cleaner noises and to characterize the prototype of ``the pleasant aspirator noise,'' a free categorization method was adopted. The subjects are asked to group, in a free number of categories, the noises according to the comfort sensation they evoke. By analyzing the results the role played by the typicality and the gradation phenomenon in the structures relative to these noises quality can be estimated. Finally, the organization of these categories is analyzed by estimating on one hand the relative importance of parameters coming exclusively from noises physical content, and on another hand, the significance given to the stimuli by each subject.