Abstract: A sound reproduction device or a microphone comprising an enclosure (2) which is made of a substantially gas permeable flexible material and an electrical transducer (1) having at least one connection (4, 5) with the enclosure, and usually two connections, to impart movement to the enclosure where the device acts as a loudspeaker or to receive movement of the enclosure to generate an electrical signal where the device acts as a microphone. The enclosure is adapted to be stressed by internal pressure and forms a concavity centered on at least one of the connections with the electrical transducer, which concavity acts as an acoustic diaphragm.