This invention is applicable to acoustic imaging for nondestructive testing and is particularly useful in biomedical applications for acoustic imaging of internal organs of living beings in real time. For real time ultrasonic imaging of organs in a living organism, for example, the heart in a living human body, it is important that acoustic waves be coupled to and from the specimen with a minimum loss at the interface between the specimen and the transmitter and receiver. In order to pass the acoustic waves with a minimum of reflection at the interface with the specimen, it is necessary that the coupling conform to the contours of the specimen, which contours may be highly complex. The coupling arrangement is particularly suitable for use in a system wherein the ultrasonic waves are to pass between the specimen and an ulttasonic transmitting and/or receiving system which is contained, at least partially, in a fluid medium. Thus, the coupling also serves as a closure or barrier to contain the liquid within the liquid filled container.