耳(er)廓外(wai)側面(mian)有(you)許多(duo)卷(juan)部(bu)，形同(tong)(tong)(tong)一組凹面(mian)鏡(jing)，它們可以(yi)是外(wai)界傳(chuan)來的(de)聲(sheng)(sheng)(sheng)音發生(sheng)反射和折射，從而使聲(sheng)(sheng)(sheng)音在(zai)麥克(ke)(ke)風位置(zhi)處(chu)的(de)聲(sheng)(sheng)(sheng)壓增(zeng)大(da)。與(yu)耳(er)背式助(zhu)(zhu)(zhu)聽器(qi)(qi)相比，耳(er)內式助(zhu)(zhu)(zhu)聽器(qi)(qi)的(de)麥克(ke)(ke)風位于耳(er)內，其(qi)助(zhu)(zhu)(zhu)聽效果就(jiu)是因為(wei)這一原理(li)而增(zeng)強(qiang)。耳(er)內式與(yu)耳(er)背式助(zhu)(zhu)(zhu)聽器(qi)(qi)所占耳(er)甲腔/或(huo)外(wai)耳(er)道外(wai)耳(er)道的(de)解剖外(wai)置(zhi)不(bu)(bu)同(tong)(tong)(tong)，且不(bu)(bu)同(tong)(tong)(tong)款式的(de)耳(er)內式助(zhu)(zhu)(zhu)聽器(qi)(qi)的(de)麥克(ke)(ke)風位置(zhi)不(bu)(bu)同(tong)(tong)(tong)，因此其(qi)聲(sheng)(sheng)(sheng)增(zeng)益(yi)也有(you)所不(bu)(bu)同(tong)(tong)(tong)。高建林(lin)的(de)實驗說明(ming)CIC麥克(ke)(ke)風處(chu)的(de)聲(sheng)(sheng)(sheng)增(zeng)益(yi)大(da)，其(qi)次(ci)為(wei)ITC，再者(zhe)ITE。