New Acoustic Test Procedure for Hard Floor Covering Systems with Soft Underlay

Walking with hard heeled shoes generates especially on laminate floorings a well noticeable “clack-clack” sound. Heard in the same room where the walker is, this sound is called “walking sound” and sometimes also “drum sound”. In order to qualify acoustically the different flooring products, a test method is needed. The goal was to define a reliable measurement method which provides comparable results to real walking of an experienced walker using a reference shoe. Numerous studies have shown that the ISO tapping machine used in building acoustics is not adequate for this purpose. After a review of the properties of the impact and the floor response, attention is given to the interaction of the impedance of shoe and floor. In contrast to a heavy concrete floor, the hard floor covering system with a soft underlay has impedance values in the same order of magnitude than the impacting heel. Thus, there is no easy way around: If an impacting hammer is expected to evoke the same floor excitation than the shoe's heel, the hammer has to have about the same source impedance than the shoe. An impact hammer with a weight of 200 grams an a rather hard, resilient tip of 1.3 MN/m fulfills this requirement.