The noise generated from drainage equipment in residential buildings is classifiable as air- and structure-borne sound as a whole. Various investigations of countermeasure for drainage noise are conducted by research organizations. In this study, measurements of noise and floor vibration emitted by drainage equipment were performed by using a test tower at 23.1m height, and measurement indexes of radiated noise from drainage stacks and fittings were examined. In addition, the characteristics of noise and floor vibration under various flow rate conditions were investigated. Results revealed that it is effective to use the time-average sound pressure level L_eq or percentile sound level L₅ properly according to the drainage time, as a measurement index of drainage noise from a practical perspective. Furthermore, the A-weighted sound pressure levels of falling water in the vertical pipes were dominated by frequency components of 2kHz or more, and increased linearly with the logarithm of the flow rate. These tendencies were seen in the measurement results of vibration acceleration level on the floor.

The authors have re-examined the equation of attenuation with distance in INCE/J RTV-MODEL 2003 and investigated the expansion of the equation to banked road and cut road by technique of physical mathematics using 2.5-dimensional numerical method. Though the investigation results were obtained under limited conditions which are modeling of pavement, ground, large car and road structure, it is founded that there is no problem concerning the consistency of taking the distance along ground surface on the applicability of the equation of attenuation with distance in RTV-MODEL 2003 to banked road and cut road.