Field measurement on the comfort level of acoustic environment in coastal zone

Recently, waterfront areas have come to be utilized more and more by an increasing number of peoples for various purposes. Accompanying this change, various environmental problems inherent to waterfronts have surfaced in terms of the possibility of human activities in such areas, their habitability, and comfort levels in relation to humans. To develop a waterfront area as an attractive space, it is essential to ensure that the area has a comfortable natural environment. In other words, it is important to study physical factors and phenomena that greatly influence the natural environment, and human beings, are interrelated; and to compile, based on study findings, necessary concepts and techniques for realizing waterfront areas that are urban environments highly compatible with human activities. From this perspective, field measurements were conducted to establish the characteristics of wave sound at various waterfront locations, in terms of the comfort level of the acoustic environment. In front of the embankment of a final disposal site for industrial wastes developed as reclaimed land in Kitakyushu City, Japan, natural rocks were installed instead of artificial wave dissipating concrete blocks, in consideration of not only effectiveness in dissipating wave energy but also landscape. Measurements and questionnaire surveys were conducted for comparison of the fundamental characteristics of wave sounds at various types of waterfronts. It was found that not only a more natural sounding acoustic environment but also effective dissipation of wave energy similar to the characteristics of a natural coast could be achieved by placing natural rocks in front of an artificial embankment.