耳(er)廓外(wai)(wai)側(ce)面(mian)有許多(duo)卷部(bu)，形同(tong)(tong)(tong)(tong)一組凹面(mian)鏡，它們(men)可以是(shi)外(wai)(wai)界傳來的(de)(de)(de)聲(sheng)音發生反射(she)和折射(she)，從而(er)使(shi)聲(sheng)音在麥(mai)(mai)克(ke)(ke)風(feng)位(wei)置(zhi)處的(de)(de)(de)聲(sheng)壓增(zeng)大。與(yu)耳(er)背式助聽器相(xiang)比，耳(er)內(nei)(nei)式助聽器的(de)(de)(de)麥(mai)(mai)克(ke)(ke)風(feng)位(wei)于(yu)耳(er)內(nei)(nei)，其助聽效果就是(shi)因為(wei)這一原理(li)而(er)增(zeng)強。耳(er)內(nei)(nei)式與(yu)耳(er)背式助聽器所占耳(er)甲腔/或外(wai)(wai)耳(er)道外(wai)(wai)耳(er)道的(de)(de)(de)解剖(pou)外(wai)(wai)置(zhi)不(bu)(bu)(bu)同(tong)(tong)(tong)(tong)，且(qie)不(bu)(bu)(bu)同(tong)(tong)(tong)(tong)款式的(de)(de)(de)耳(er)內(nei)(nei)式助聽器的(de)(de)(de)麥(mai)(mai)克(ke)(ke)風(feng)位(wei)置(zhi)不(bu)(bu)(bu)同(tong)(tong)(tong)(tong)，因此其聲(sheng)增(zeng)益也有所不(bu)(bu)(bu)同(tong)(tong)(tong)(tong)。高建林的(de)(de)(de)實(shi)驗說明CIC麥(mai)(mai)克(ke)(ke)風(feng)處的(de)(de)(de)聲(sheng)增(zeng)益大，其次(ci)為(wei)ITC，再(zai)者ITE。