耳(er)(er)廓外側(ce)面有(you)許多(duo)卷部，形同(tong)(tong)一組凹(ao)面鏡，它們(men)可以是外界(jie)傳(chuan)來的(de)聲(sheng)(sheng)音發生反射和折(zhe)射，從而(er)使聲(sheng)(sheng)音在麥(mai)(mai)克(ke)風(feng)(feng)位(wei)置處的(de)聲(sheng)(sheng)壓增(zeng)(zeng)大(da)。與(yu)耳(er)(er)背式(shi)(shi)(shi)助(zhu)聽(ting)器(qi)相比，耳(er)(er)內(nei)式(shi)(shi)(shi)助(zhu)聽(ting)器(qi)的(de)麥(mai)(mai)克(ke)風(feng)(feng)位(wei)于耳(er)(er)內(nei)，其助(zhu)聽(ting)效果就(jiu)是因為(wei)這一原理而(er)增(zeng)(zeng)強。耳(er)(er)內(nei)式(shi)(shi)(shi)與(yu)耳(er)(er)背式(shi)(shi)(shi)助(zhu)聽(ting)器(qi)所占耳(er)(er)甲腔/或外耳(er)(er)道(dao)(dao)外耳(er)(er)道(dao)(dao)的(de)解剖外置不(bu)同(tong)(tong)，且(qie)不(bu)同(tong)(tong)款式(shi)(shi)(shi)的(de)耳(er)(er)內(nei)式(shi)(shi)(shi)助(zhu)聽(ting)器(qi)的(de)麥(mai)(mai)克(ke)風(feng)(feng)位(wei)置不(bu)同(tong)(tong)，因此(ci)其聲(sheng)(sheng)增(zeng)(zeng)益也(ye)有(you)所不(bu)同(tong)(tong)。高建林的(de)實驗說(shuo)明CIC麥(mai)(mai)克(ke)風(feng)(feng)處的(de)聲(sheng)(sheng)增(zeng)(zeng)益大(da)，其次為(wei)ITC，再者ITE。