The present invention provides an acoustic coupling interface (1) for use between a flexible ultrasound transducing device (2) and a curved object (3) to be examined. The interface (1) is in the form of a sheet (4) having a bending flexibility that permits the sheet (4) to form a continuous contact with said curved object (3) during operation of the flexible ultrasound transducing device (2). Further, the sheet (4) comprises a bulk material (5) and a plurality of acoustic waveguiding structures (6) arranged in said bulk material (5), wherein the plurality of acoustic waveguiding structures (6) is for providing bidirectional coupling of ultrasound signals (7) emitted by the ultrasound transducing device (2).