TABLE I. AUC (2013) estimates of average overall A-weighted nighttime ambient SPL. Population density in persons per square kilometer (km) was derived from the specified dwelling density per quarter section (where quarter section is interpreted as an area with 454m radius) assuming 2.9 persons per Canadian farm dwelling (Statistics Canada, 2011). To convert to either DNL or daytime SPL add 10dB to the levels in the table.