A sound transmitter includes at least a vibrating membrane mounted on the wall of an enclosure so that one surface of the speaker membrane radiates in the enclosure, the enclosure being provided with a vent forming a conduit between an outlet inside the enclosure and an outlet outside the enclosure. The vent comprises aerodynamic turbulence attenuating elements at least at one of the outlets, the turbulence resulting from an air stream caused by the large amplitude displacements of the membrane. The invention also concerns a sound transmitter wherein air moves in a conduit (33) extending from the membrane to an outlet (35) of the conduit (33) on the outside. The invention further concerns a speaker whereof the members have an aerodynamic shape.