Under Singapore's Environmental Protection and Management (Control of Noise at Construction Sites) Regulations, Second Schedule, the 12 hours equivalent continuous noise level(LEQ12hrs) maximum permissible noise level for construction sites are set based on a start time of 7am and end time of 7pm for the DAY period. And from 7pm to 7am for the NIGHT period.  In order to know the 12hr Leq, a 12-hr measurement time would h...