底下引自ER4的发明者之一Don Wilson (lasergloom的帖中的专利内容里有他的名字) 在Head-fi的发言:
Deep insertion does not equal a good seal. It depends on you rear canal shape and how you insert the eartips.
……
I have seen some people that try to make the whole earphone disappear down their ear canal. You will get a little more sound pressure and more highs if you do this, but it is not necessary.