A very unusual implement designed to
test bone conduction. The tiny ear tube dissembles to reveal a metal
disc which is held firm by two springs at either side. When inserted
in the ear the small metal dumbbell is struck against the rim of the
ear tube and causes the disk to vibrate. The resulting bizarre
twanging noise sounds more like something out of the 'Magic
Roundabout'. Whether or not this could quantify bone conduction is
dubious - but it is nonetheless a superb little instrument!
