Structural analysis of the value evaluation of vehicle door-closing sounds

Vehicle door-closing sounds affect the commercial value of vehicles. To create a door-closing sound that adds vehicle value, it is necessary to grasp and control factors affecting the value evaluation, such as the sound quality and imagery associated with the door-closing sound. The present study conducted psychoacoustic experiments to comprehensively investigate factors affecting the value evaluation of door-closing sounds and its structure using the evaluation grid method. Pairs of door-closing sounds were presented to participants. Participants were asked to select the more satisfactory stimulus and to give reasons for their selection so as to clarify original evaluation factors (i.e., perspectives in evaluation). Furthermore, to elicit factors relevant to the obtained evaluation factors at higher/lower levels of the hierarchical structure, participants were asked to identify benefits (i.e., reasons why they provided the original evaluation factors) and their detailed concrete requirements (mainly acoustic characteristics of stimuli). The overall structure was obtained from relationships between original evaluation factors and elicited factors at the higher/lower levels for all paired comparisons of door-closing sounds of all participants. The results reveal that door-closing sounds with abundant low-frequency contents and rapidly damped energy aroused feelings of solidity and the door being firmly closed. Furthermore, these feelings were related to emotional benefits such as a sense of security and an impression of the luxuriousness of the vehicle. Relationships between ratings of paired comparisons and metrics confirmed the effects of acoustic features of door-closing sounds found in the structure. The results suggest factors important to the design of door-closing sounds. Furthermore, to clarify details such as differences in factors among door-closing sounds and differences due to participants’ attributes, further psychoacoustical experiments were conducted in a similar manner. Text mining was applied to participants’ answers. At the start of analysis, tags relating to stimuli (what types of stimuli were described), negative/positive feelings (whether answers were given in a positive context), and enthusiastic/unenthusiastic feelings about cars (whether answers were given by car enthusiasts) were attached to all answers. Correspondence analysis was applied to the sentence-word (tag) table obtained in text mining. As a result, a two-dimensional solution displaying relationships in terms of location among words and tags was obtained. Furthermore, through hierarchical cluster analysis, words and tags were classified into five clusters. One of the clusters comprised the tag “positive” and words such as “heavy”, “solidly made”, “low pitch”, and “bass”. Such relationships were similar to major structures of the value evaluation. Results also revealed relationships concerning other tags. Words related to tags such as “positive” and “enthusiastic” are supposed to indicate the design direction of door-closing sounds.