EXTERNAL MOBILITY OF THE EARDRUM.

Introduction THE COMPLEX nature of any studies on the ear can readily be appreciated from reading Helmholtz on The Sensations of Tone 1 and Bekesy and Rosenblith on "The Mechanical Properties of the Ear." 2 These latter authors indicate that our knowledge of the mechanical properties of the ear are sketchy, and even more fragmentary is our understanding of the translation of mechanical processes into neural stimuli. They also indicate that a great deal of the difficulty is related to the inaccessibility of this mechanical transducer system. Measurements of the internal mobility of the eardrum have been made as reported by Bekesy 2 which contains a bibliography of these studies, but no mention is made of recordings of the external mobility of the eardrum, the effects of external deformation of the eardrum from its normal physiological position on hearing, and the presence of a recordable arterial pulse by way of the