A.波長(zhǎng)為1m的聲波; B.波長(zhǎng)為10cm的聲波; C.波長(zhǎng)為10m的聲波; D.波長(zhǎng)為1cm的聲波; E.波長(zhǎng)為100m的聲波。
A.三棱錐 B.三棱柱 C.四棱臺(tái) D.六面體 E.八面體
A.全向性助聽(tīng)器和方向性助聽(tīng)器; B.線(xiàn)性助聽(tīng)器和非線(xiàn)性助聽(tīng)器; C.調(diào)頻助聽(tīng)器和紅外線(xiàn)助聽(tīng)器; D.數(shù)字助聽(tīng)器和模擬助聽(tīng)器; E.植入助聽(tīng)器;
A、1/2kHz; B、22kHz; C、21/2kHz; D、(1/2)2kHz; E、(1/2)1/2kHz。
A.炭精助聽(tīng)器; B.半導(dǎo)體眼鏡式助聽(tīng)器; C.耳后式助聽(tīng)器; D.集成電路助聽(tīng)器; E.駐極體傳聲器助聽(tīng)器。