Abstract:
In the area of floor impact testing, a number of excitation techniques have been used for evaluating the degree of sound transmission. The ultimate goal of the excitation is to replicate the force and time duration of a human footfall so one can reliably rank the acoustical quality of the floor/ceiling system. The most common excitation methods involve dropping some object from a known height so the kinetic energy delivered to the floor is consistent. The limitation of the energy method is that the force spectrum imparted to the floor can vary if the floor finish has unstable or nonlinear characteristics (e.g., a thick carpet). In order to control this parameter, research laboratories have occasionally used a force sensor to help calibrate the impact forces from dropped objects. This paper will discuss the concept of using a force sensor as one component of a stimulus--response impact sound measurement in the field. A unique 13-kg force transducer ``platform'' was constructed in order to perform the field experiments. The platform is capable of measuring large dynamic forces at frequencies up to 100 Hz. Some examples of two-channel field data (force versus sound pressure) will be presented to demonstrate the technique.