Abstract: A respirator speech transmitter has a projecting tube with a one-way valve at one end and the other end being covered by a baffle having an inner skirt extending around the tube. An outer skirt extends from the tube to surround the inner skirt so that an annular convoluted passageway which increases in annular width as it extends from the tube formed between the outer surface of the tube, the inner skirt and the outer skirt. This convoluted passageway has excellent acoustic properties yet prevents ingress of contaminants. In a modification the valve is at the same end of the tube as the baffle.