A method proposal for measuring sound perception and quality in product design: Study on vacuum cleaners

Sound design, one of the components of user experience design is a complicated process that includes psychological background, sensory perceptions, and relationships between concepts and products. Besides, it needs to be approached with an inclusive perspective. It carries more importance for designers how users perceive product sounds rather than what kind of sounds products have. Not only the concept of user experience increases in importance, but the need for knowledge sources that envisions the features of the product sound for meeting the expectations of users increases as well. This thesis study aims to identify user perceptions regarding sounds, how users explain these perceptions, and which sound features are effective in the occurrence of these perceptions. Interviews with 20 design students have been carried out in this matter by using the repertory grid technique which is a mixed method. Data regarding how students perceive these sounds have been collected under 22 common structures with the help of semantic content analysis in the first step. A glossary explaining how users perceive the sounds of vacuum cleaners has been created with these structures. In the second step, sound quality metrics of vacuum cleaners (Zwicker tone, sharpness, and roughness) have been calculated, their spectrums have been analyzed by using Mel Frequency Cepstral Coefficients (MFCC) and spectrogram graphics have been created. Relationships between user expressions (common structures), spectrograms, and sound quality metrics have been identified as a result of this study.