Patients in whom fistula speech has developed after laryngectomy usually have to occlude their stoma with a finger to talk. This prevents the air that is needed to activate the fistula from being exhaled through the stoma. In order to free the hand, Blom and Singer devised a diaphragm-valved stomal device known as the tracheostoma valve. This device snaps into a flexible retention housing that must be carefully cemented to the skin. Some patients who have undergone near-total laryngectomy (and others with tracheo-esophageal voice prostheses) are unable to use their devices because the moisture and pressure around their stomas break the seal. Since air that is used to produce voice with the valve tends to lift the housing away from the stoma, a better housing design would assure that this motion would improve the seal.