Validate the Sound Quality Index and Discuss of Enhancing the Sound Quality About 183 to 257 kW Class Outboard Engines

This paper discussed the sound quality which assumed important factor in the development of outboard engines in the 183 to 257 kW class in the future. Many kinds of industrial product development dealt with sound quality, and there were many examples using sound quality index adapted customer requirements or products usage. In case of outboard engine development, there were examples of noise reduction and compliance with noise regulations, but there was almost no example of sound quality development. This research proceeded a questionnaire survey of 90 boat owners who were listening to several cruising engine sounds in main market, US. From this result, authors discussed customer trend and extracted 3 sound quality indexes, luxury, deep and sporty, which were demanded in our target class. Next step was that authors made simulation sounds referring 3 sound quality indexes to verify customer’s trend. Using these simulation sounds, authors re-tried to a questionnaire survey, we were able to confirm trends in sound quality preferred by customers. Finally, authors suggested that it was important for realizing customer’s preference sound quality to control the air intake noise and the gear noise.