| 摘要 |
PURPOSE: To reduce the noise in an excellent way and to avoid a damage when dropped by including a viscoelastic layer having a specific dynamical shear loss factor in a hearing aid. CONSTITUTION: A viscoelastic layer 16 has at least a loss rate of 0.5 and at least a shear storage rate G' of 10<7> dyne/cm<2> at 1000Hz and 38 deg.C (100 deg.F). A dynamical shear loss factor G" (that is, a product between the loss rate and the shear storage rate G') is desirably at least 1.5×10<7> dyne/cm<2> to provide excellent insulation of a microphone. Moreover, excellent insulation is obtained when the dynamical shear loss factor G" is at least 2.5×10<7> dyne/cm<2> at 1000Hz and 38 deg.C. Thus, noise amplified by a receiver 17 of the hearing aid 10 is reduced, and damage to components of the hearing aid 10 is prevented even when the hearing aid 10 is dropped.
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