In many engineering fields, distance to target is very important information. As a typical method, distance is estimated by measuring time delay between transmitted and reflected waves. However, it is difficult to estimate short distance by a method like this. On the other hand, a method using standing wave to measure short distances has been known in the field of microwave radar. We have applied this method to distance estimation using audible sound and shown the validity of that through our simulations and experiments. In this paper, we present the prototype system for distance estimation in which this method is implemented, and evaluate the performance of this system by experiments in actual sound field.