Methods and systems for delivering fluids, aerosols, and/or acoustic energy to target sites on tissue surfaces and within body cavities or lumens, obstructions or undesired materials associated with body cavities and tissue surfaces and, particularly, target sites on tissue surfaces or at obstructions within natural orifices, such as ear, nose and throat passages and, particularly, nasal passages and cavities, are provided. Delivery of acoustic energy may be accomplished using a flexible, expandable member adapted to be expanded at a target site using an acoustically transmissive material for delivery of acoustic energy to tissue surfaces in irregularly configured tissue cavities and passageways.
