Abstract: A matrix or array of elongated tubular members, each member being formed by spirally winding a piece or pieces of material into a generally cylindrical shape, wherein the matrix or array is mounted in an airflow to reduce the noise associated with and/or produced by the airflow.

Abstract: A matrix or array of elongated tubular members, each member being formed by spirally winding a piece or pieces of material into a generally cylindrical shape, wherein the matrix or array is mounted in an airflow to reduce the noise associated with and/or produced by the airflow.

Abstract: The invention provides a marine propulsion device comprising a powerhead including an exhaust gas discharge port, a gearcase rotatably supporting a propeller shaft connected to the powerhead and including an exhaust gas discharge, and a lower unit including an upper portion supporting the powerhead and a lower portion connected to the gearcase, with the lower unit comprising an inner exhaust housing having a generally vertical wall, an open top in communication with the powerhead exhaust gas discharge port, a bottom having therein a first exhaust gas outlet and a second exhaust gas outlet at the top portion of the wall, and an outer exhaust housing also having a generally vertical wall in surrounding relation to the inner exhaust gas housing and defining a vertically extending generally annular space between the inner and outer exhaust gas housings, the space communicating with the second exhaust gas outlet.