A terminal unit of a heating, ventilation, and/or air conditioning (HVAC) system includes a fan configured to provide an airflow through the HVAC unit by drawing the airflow into a fan inlet and expelling the airflow out of a fan outlet. The terminal unit also includes an inlet diffuser disposed upstream of the fan inlet relative to a direction of the airflow, wherein the inlet diffuser includes a first layer of perforated metal and a second layer of perforated metal disposed between the first layer of perforated metal and the fan inlet.