47. 下列何者是計算聽力損失指標六分法之公式？ (A)(500Hz 聽力閾值+1000Hz 聽力閾值+2000Hz 聽力閾值+4000Hz 聽力閾值)/6 (B)(500Hz 聽力閾值+2×1000Hz 聽力閾值+2000Hz 聽力閾值+4000Hz 聽力閾值)/6 (C)(500Hz 聽力閾值+2×1000Hz 聽力閾值+2×2000Hz 聽力閾值+4000Hz 聽力閾值)/6 (D)(500Hz 聽力閾值+1000Hz 聽力閾值+2×2000Hz 聽力閾值+2×4000Hz 聽力閾值)/6