A speech valve (10) has a body (12, 14,16) and a projection (82). The body (12, 14, 16) is at least partially insertable into a fistula between the trachea and the oesophagus so as to provide a closable passage between the trachea and the oesophagus with the projection (82) lying outside the fistula to resist passage of the valve (10) through the fistula. The body (12, 14, 16) has a seat (30) and the valve includes a closure member (62) which is movable between an open position and a closed position in which the closure member (62) contacts the seat (30) so as to close the valve (10) and thereby close the passage between the trachea and the oesophagus. The body (12, 14, 16) and the closure member (62) have respective guidance surfaces (58, 66) which slidingly contact one another to guide the closure member (62) between the open and the closed positions so that the sliding contact tends to clean the guidance surfaces (58, 66). The body (12, 14, 16) and the closure member (62), or at least their respective closure surfaces (58, 66) are made of a ceramic material. In one preferred embodiment, the closure member (62) is biased towards the closed position by a repulsive magnetic force. In another preferred embodiment, the closure member (62) rotates relative to the body as it moves axially between the open and closed positions.
