Sound that was being heard in the back operational room was caused by heavy airflow. Technician located manual air volume damper, on ductwork and adjusted airflow down to reduce sound. Technician also made observation that the equipment does not appear to have had any maintenance since installation having original filters that come with the equipment. Technician highly recommends that all three systems be serviced thoroughly, including replacing filters and belt replacement and/or adjustments. Estimate for maintenance of the systems will be provided via email.