Jongkees & Groen investigated from which direction a test person with closed eyes would estimate that a sound is coming. In order to obtain objective and measurable results they used a graduated circle (radius 50 cm) along which the sound source could be moved and on which the test person was requested to indicate where he thought the source was situated. As a diagram of his directional hearing, the subjective place, as indicated by the test person, was plotted as a function of the objective place, both in degrees as marked on the arc graduation.Directional hearing is examined in a group of patients suffering from various types of loss of hearing. The results are compared with the diagram for directional hearing in the horizontal plane as found in a series of normal test subjects. Statistically a probable limit value for directional hearing in the horizontal plane is obtained by using Wilcoxon's symmetry test.Otitis media chronica, atresia, nerve deafness, otosclerosis, fenestration, tympanoplasty and uni...