No abstract

Obtaining the dynamic properties of resilient materials is a subject that has been extensively researched by other workers using a variety of techniques; many of these techniques use detailed numerical methods. In this paper a simplified approach has been adopted which allows the dynamic stiffness of resilient layers to be predicted at higher frequencies where wave effects across the thickness of the layer are important. The method is a development of the technique used in the ISO Standard 9052-1. However, the ISO Standard method will only give the stiffness at one frequency whereas the method in this paper gives the stiffness across a frequency range. Reasonable agreement with measurements is shown.

When impact sound tests are carried out in new and refurbished flats there is not normally a load on the floor. When the flat is occupied however, loading due to furniture, appliances, people etc, will occur which compresses the resilient layer if a floating floor construction has been used. The effect this has on impact sound insulation is considered in this paper. Impact sound transmission through a chipboard floating floor on battens supported on a concrete floor has been measured when static loads were placed on the chipboard – the loads were in the range 20 kg/m3 to 160 kg/m2. Three different resilient layers under the battens were tested: 25 mm mineral wool quilt, resilient battens and resilient battens on 13 mm mineral wool quilt. The weighted standardised impact sound pressure level (L'nTw) increased by 0.5 dB to 5 dB with the larger increases for the greater loads. Further measurements were made after the floating floors had been left under a static load of 200 kg/m2 for six months: there was an additional increase in L'nTw of 1.5 dB. Finally, measurements were compared with floors where the resilient layers had been soaked to simulate water leakage from baths, pipes etc; there was no significant difference in results.