Objectives/Hypothesis: The aim of this study was to establish the sound transmission characteristics of cartilage conduction proposed by Hosoi (2004), which is available by a vibration signal delivered to the aural cartilage from a transducer.Study Design: Experimental study. Method: Eight volunteers with normal hearing participated. Thresholds at frequencies of 0.5, 1, 2, and 4 kHz for air conduction, bone, and cartilage conductions were measured with and without an earplug. The sound pressure levels on the eardrum at the threshold estimated with a Head and Torso Simulator were compared between air and cartilage conductions. The force levels calibrated with an artificial mastoid at the threshold were compared between bone and cartilage conductions.Results: The difference in the estimated sound pressure levels on the eardrum at the thresholds between air and cartilage conductions were within 10 dB. In contrast, the force levels at the thresholds for cartilage conduction were remarkably lower than those for bone conduction. These findings suggested that sounds were probably transmitted via the eardrum for cartilage conduction. The threshold shifts by an earplug showed no significant difference between bone and cartilage conductions at 0.5 kHz. At 1 and 2 kHz, the threshold-shifts increased significantly in the order of bone, cartilage, and air conductions. These results suggested that airborne sound induced by the vibration of the cartilaginous portion of the ear canal played a significant role in sound transmission for cartilage conduction.Conclusions: Cartilage conduction has different characteristics from conventional air and bone conductions.

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Anorthite megacrysts are common in basalts from the Japanese Island Arc, and signally rare in other global fields. These anorthites are 1 to 3 cm in size and often contain several corroded Mg-olivine inclusions. The megacrysts generally range from An94Ab4Ot2 to Ans9Ab6Ot5 (Ot: other minor end-members, including CaFeSi3Os, CaMgSi3Os, A1A13SiO8, [-]Si408) and show no chemical zoning. They often show parting. Redclouded megacrysts contain microcrystals of native copper with a distribution reminiscent of the shape of a planetary nebula. Hydrocarbons are also present, both in the anorthite megacrysts and in the olivines included within them. Implications of lateral variations in the Fe/Mg ratio of the included olivines, in Sr-content and in Sr-isotope ratio of the anorthite megacrysts with respect to the Japanese island arc, relate to mixing of crustal components and subducted slab-sediments into the basaltic magmas. I~uanorthite, megacryst, island a.:, Japan, basalt.

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