Although Kuk et al showed that the

Although Kuk et al showed that the acoustic mass of the vent was closely related to the SPL levels in the residual cavity, they also found that acoustic mass is not highly related in a systematic manner to the patient’s perceived amount of the occlusion effect (.Fig. 4.19). Other investigators also have found fairly small or only modest correlations between objective measurements and subjective ratings of the occlusion effect or none at all. At the extremes we know a very small, long vent will invariably elicit a judgment of a significant hollowness, while very short vents and those with diameters of 4 mm or larger usually serve to significantly reduce or eliminate it altogether. Between those two extremes, it appears that the own-voice experience of occlusion is a subjective phenomenon and its relation to objective measurements is inconstant.