I.down1[美 daʊn, 英 daʊn]副down often appears as the second element of certain verb structures in English (back down, clamp down, tone down, etc). For translations, see the relevant verb entry (back, clamp, tone, etc).
I.on [美 ɑn, ɔn, 英 ɒn]介词on often appears as the second element of certain verb structures in English (count on, lay on, sign on, etc). For translations, see the relevant verb entry (count, lay, sign, etc).
The friction is slight, and we were able to effortlessly press down on the button without thinking about the fact that there's no dedicated touch button (nevermind two).
What really puts us off buying these headphones is the catastrophic internal design, which causes driver deformation if you press down on the ear cups while they're on your noggin.