[Effect of occlusion. Part II. Theoretical and practical implications].

The theoretical and practical consequences of the experiments described in part I are discussed. They concern the following topics: 1. The stability of the occlusion effect: in contrary to the opinions expressed in the literature--the stability of the effect for a particular earphone is of range of normal deviation in threshold of hearing. 2. Bone conduction threshold shift in occlusion effect represents change in proportions of the air- and bone-components of the normal bone conduction threshold: an increase of the air component on the expense of the bone component. The shift do not represents the change in perception. In that respect the shift is a spurious phenomenon. 3. Depending on the presence or the lack of occlusion effect all the ears were divided into classes: "occlusive" and "non-occlusive". a) the occlusive ears include the ones with normal conduction (healthy or the hearing- impaired ears) covered with earphones during bone conduction tests, b) the non-occlusive are the ears mentioned under "a", but unoccluded and all the ears with conductive loss (regardless the occlusion). The audiometric norm for bone conduction threshold, established in non-occlusive state (which is the usual procedure in the conventional audiometry) are suitable only for the non-occlusive ears. And vice versa: the occlusion norm (found in a routine Rainville procedure) may be applied only for occlusive ears.