Two recent noise control projects related to the reduction of noise from mechanical equipment rooms to an adjacent conference room and to an adjacent office. For both of these situations, the noise control procedures to be implemented involved the determination of the most significant noise transmission path; air borne noise transmitted through a concrete floor slab or structurally transmitted noise due to lack of proper chiller and pipe vibration isolation in the conference room case, or for the office case airborne noise transmitted through a wall constructed of gypsum wall board and flanking through common floor slabs or structurally transmitted due to lack of suitable pump and piping vibration isolation. A method for determining the most significant noise transmission path and the resulting noise reduction for these two cases will be described.