Little attention has been given to sound as an element of interaction although an interaction design utilizes five senses of the human being. While designing the portable microwave oven, we selected the sound as a topic of our study. As several sounds have already been applied to products, such as the buzz sound in the walk signal or a warning sound in the computer, the focus of research is that the sound may have to be different vis-à-vis the product's functionality or locations where it is used. Conclusions have not been made a priori that a product developer should create new sounds for new products. For this purpose, the research has been conducted to develop the sound concept in nexus with the product and the outdoor environment. Developed sounds were then evaluated and analyzed by a target audience. With this analysis, we were able to adopt proper portable microwave oven sounds that allowed potential users to feel familiar, to respond pleasantly amid outdoor noises, and to expect the taste of food. During the course of the experiment, we came to the conclusion that even with the same sound and some modifications made by applying different lengths, tones, rhythms, and/or resonance allowed users to recognize the functions or features of the products. The results have changed our evaluation on the sound itself and will extend the value of sound interaction between human beings and products.