Re: IEMs more dangerous beyond just merely being super effic
One of the issues I have with IEMs, and in fact earplugs in general, is the loss of radiative cooling which, near the open end of the ear, is by far the most dominant method of heat transfer taking place. Having a physical object in my ear is not the problem per se, but rather it's the effect that that object has. In my case it causes an uncomfortable temperature increase after a fairly short period of time.
Another example: while swimming I rely on water moving in and out of the outer ear cavity to provide some cooling (through conduction, rather than radiation). At the other end of the spectrum, when swimming in very cold water conditions I need to use earplugs to prevent too much heat loss, which tends to lead to pain, disorientation and dizziness (by messing with the vestibular system.)