The quietness of a living space greatly affects the quality of life of its residents. To maintain the quietness of an indoor space, a solution is required for the floor impact sounds that have over the years generated several civil complaints to the National Noise Information System. Accurate measurement and evaluation of the floor structure are important factors for solving the floor impact sounds. To reproduce the sound effect of children running on the floors accurately, a new impact source is designed that complements the current standard impact sources. Prior to the designing, the important factors were investigated via a questionnaire answered by experts. The experts'' opinions reflected that further information was required about the step length and velocity of children running. Experiments were conducted to collect this data. The results showed that the factors showing positive correlation with the step length and velocity were age, height, and weight. The gender of a child was not related to the step length and velocity. To depict the step length and velocity based on the investigated data, the radius and angular velocity of the impact parts of the new impact source was calculated.