Noise suppression systems

An engine comprising:

• a cylinder that generates or transfers noise having a frequency within a noise frequency range, the cylinder comprising a side surface;
• a plurality of cooling fins extending radially from the side surface of the cylinder;
• a micro-perforated cylinder wrap comprising a micro-perforated sheet positioned a first distance from the side surface of the cylinder, the micro-perforated sheet positioned proximate to ends of the cooling fins and comprising a plurality of micro-perforated holes, the micro-perforated sheet configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet;
• and
• a baffle wall positioned at a second distance from the cylinder wrap and collectively forming a micro-perforated panel with the micro-perforated sheet, the second distance defining a cavity creating an air space between the baffle wall and the micro-perforated sheet;
• wherein the parameters include the distance from a boundary and dimensions of the micro-perforated holes, and wherein the parameters are set such that the absorption frequency range overlaps the noise frequency range.

An engine comprising:

• a cylinder that generates or transfers noise having a frequency within a noise frequency range, the cylinder comprising a side surface;
• a plurality of cooling fins extending radially from the side surface of the cylinder;
• a micro-perforated cylinder wrap comprising a micro-perforated sheet positioned a first distance from the side surface of the cylinder, the micro-perforated sheet positioned proximate to ends of the cooling fins and comprising a plurality of micro-perforated holes, the micro-perforated sheet configured to absorb sound within an absorption frequency range based on parameters of the micro-perforated sheet;
• and
• a baffle wall positioned at a second distance from the cylinder wrap and collectively forming a micro-perforated panel with the micro-perforated sheet, the second distance defining a cavity creating an air space between the baffle wall and the micro-perforated sheet;
• wherein the parameters include the distance from a boundary and dimensions of the micro-perforated holes, and wherein the parameters are set such that the absorption frequency range overlaps the noise frequency range;
• wherein the second distance is selected so that the cavity absorbs noise within the noise frequency range of the noise generated by the cylinder.