Equalization for the dummy-head-headphone system capable of reproducing true directional information

Of the dummy-head-headphone system, consisting of a dummy-head, headphones, and a listener, a method of equalization for precise reproduction of the original sound is studied. Three items are examined;(1) To express sound pressure at the eardrum quantitatively by taking account of the influence of the earcanal being closed by the headphone, (2) To obtain required characteristics of the equalizer, (3) To make clear the condition to be satisfied in order that the characteristics of the equalizer are independent of the direction of incident sounds. As a result, the required characteristics of the equalizer are given in terms of whole elements of the system. And it is found that the external shape of the dummy-head should be identical to the shape of the head of the listener in order that the equalizer suffices the requirements irrespective of the direction of incident sounds. The validity of the equalizer is verified by the experiment using the spherical head.