Impulsive noise measurements in a forest during summer and winter conditions

A series of tests were conducted over a a-year period to investigate the pr opagation of blast waves from explosive charges over forested regions. Thes e tests were conducted in two seasons, at the same location, to experience "summer" and "winter" (snow covered) conditions. The purpose of the tests w as to record the noise from controlled explosions of unconfined plastic exp losive at various locations in the forest to aid in the development of pred ictive methodologies for determining noise levels around forested test regi ons and bombing/firing ranges, This information is valuable to both test or ganizations and military units as a management tool to control noise output into the neighboring communities. Sound pressure and ground motion measure ments were made by agencies from five different countries at locations with distances less than 1 and up to 23 km from an explosive source. At these l ocations, measurements were also made at various heights up to 30 m and bel ow the ground surface. The source size was varied in yield and the location of the source was moved from test to test. Extensive weather measurements were also made within each measurement array from ground based systems and radiosondes reaching up to several hundreds of meters. In addition to the a forementioned, several measurements were taken to determine the impedance o f the ground cover and snow covered ground, the density of the foliage, and the depth and nature of the snow cover (depending on the winter or summer conditions). Currently, the data from the measurements (numbering nearly 80 000 separate recordings) are being stored in a database which is available for analysis and use by interested agencies. This pager provides an overvi ew of this test series, the measurements made, the current status of the pr oject, and the plans for the future and forms an introduction to the more d etailed presentations which follow. (C) 1998 Institute of Noise Control Eng ineering, [S0736-2501(98)00405-6].