Pieter Schevenels , Lieven De Geetere, Nathalie Geebelen, Gerrit Vermeir, Bart Ingelaere

1. A comparison between the structure-borne sound generated by a low-frequency vibrating plate mounted on a light-weight structure and on a heavy-weight structure Pieter Schevenels, Lieven De Geetere, Nathalie Geebelen, Gerrit Vermeir, Bart Ingelaere

2. Outline • Introduction • Experimental setup • Mobilities • Predicted and measured sound pressure levels • Conclusions A comparison between the structure-borne sound ... Pieter Schevenels et al.

3. Introduction – Experimental setup – Mobilities – Predicted and measured SPLs – Conclusions ? 1. Introduction ... • Background • Flow of power • Injection from source into structure • Distribution over structure • Radiation from structure into room • EN 12354-5 Installed power ... A comparison between the structure-borne sound ... Pieter Schevenels et al.

4. Introduction – Experimental setup – Mobilities – Predicted and measured SPLs – Conclusions ... Introduction ... • Background • Installed power (1D, single contact point) • Measuring F ... • Only in situ ... • Source and receiver ... • Measuring vsf ... • Reception plate method • (force source assumption) Source or receiver Equivalent velocity source Equivalent force source A comparison between the structure-borne sound ... Pieter Schevenels et al.

5. Introduction – Experimental setup – Mobilities – Predicted and measured SPLs – Conclusions ... Introduction • Background • Installed power (1D, three contact points) • Point mobilities Ykk and transfer mobilities Ykl • Matrix formulation → lots of variables to measure • Concept of effective mobilities • Incorporate all mobilities into one effective mobility YΣ • Assumptions about forces in different contact points • Equal • Random phase → A comparison between the structure-borne sound ... Pieter Schevenels et al.

6. Introduction – Experimental setup – Mobilities – Predicted and measured SPLs – Conclusions 2. Experimental setup ... • Vibrating plate • 24, 40 and 60 Hz • Amplitude: 3 mm • Reception plate • 2.0 x 2.8 m² • Thickness: 10 cm • Resiliently mounted A comparison between the structure-borne sound ... Pieter Schevenels et al.

7. Introduction – Experimental setup – Mobilities – Predicted and measured SPLs – Conclusions ... Experimental setup ... • Floor plates (resiliently mounted) • Wooden floor (3.0 x 3.0 m²) • Thickness: 25 cm • Fibreboard • 7 wooden joists with glass wool • 2 gypsum board plates • Concrete floor (2.0 x 2.0 m²) • Thickness: 10 cm • Floating floor (1.5 x 1.5 m²) • Thickness: 10 + 3 + 5 cm • Mineral wool layer • Light-density concrete plate A comparison between the structure-borne sound ... Pieter Schevenels et al.

8. Introduction – Experimental setup – Mobilities – Predicted and measured SPLs – Conclusions ... Experimental setup • Necessary data to predict SPL in lower room • Source characteristics • Airborne sound power level LWa • Structure-borne sound power level LWsn into reception plate • Plate characteristics • Mobility Y • Internal loss factor η • Airborne sound insulation R • Room characteristics • Reverberation time T • Volume V A comparison between the structure-borne sound ... Pieter Schevenels et al.

9. Introduction – Experimental setup –Mobilities – Predicted and measured SPLs – Conclusions 3. Mobilities A comparison between the structure-borne sound ... Pieter Schevenels et al.

10. Introduction – Experimental setup – Mobilities –Predicted and measured SPLs – Conclusions 4. Predicted and measured SPLs ... • Wooden floor Operating frequency: 40 Hz →Force source assumption invalid at high mobility A comparison between the structure-borne sound ... Pieter Schevenels et al.

11. Introduction – Experimental setup – Mobilities –Predicted and measured SPLs – Conclusions ... Predicted and measured SPLs ... • Floating floor Operating frequency: 40 Hz →Force source assumption valid at low mobility A comparison between the structure-borne sound ... Pieter Schevenels et al.

12. Introduction – Experimental setup – Mobilities –Predicted and measured SPLs – Conclusions ... Predicted and measured SPLs • Concrete floor Operating frequency: 60 Hz Operating frequency: 40 Hz Operating frequency: 24 Hz → FSA seems to be dependent on operation frequency →FSA must be valid for all frequencies A comparison between the structure-borne sound ... Pieter Schevenels et al.

13. Introduction – Experimental setup – Mobilities –Predicted and measured SPLs – Conclusions 5. Conclusions • Reception plate method • Easy method • Fewer measurements • Relatively accurate predictions • Force source assumption • Possibly still good predictions when Ys is low • But bad predictions at all frequencies when operating frequency lies in a frequency band where Ys ≈ Yi → Black-box model of source invalid → Reaction forces do influence source behaviour A comparison between the structure-borne sound ... Pieter Schevenels et al.