So heres a run down of all the possible scenarios. Just because I'm that type of guy.
Here my big mess of thoughts on all this, theres a few assumptions sprinkled here and there, so feel free to tell me if I hit the nail on the head or if I miss the mark completely.
I. Quiet Environment:
a. Headphone: Regular volume, I'll go ahead and call this X db.
b. IEM: Closer to ear, so [Assumption 1: The closer the source is, the louder it is, because sound waves deteriorate over distance] to hear it at the same volume, you will turn the volume down, resulting in the same volume X db.
b. is where most people go wrong, people assume that when you use IEMs, you don't turn the volume down. YES, it's louder, but that doesn't mean we will listen to it that way. WE. TURN. IT. DOWN. So the volume is STILL X db.
II. Noisy Environment:
a. Headphone: Due to noise, you will need to turn it up. So if [Assumption 2: Volume needed in a Noisy Environment = Volume needed in Quiet Environment + Background noise] you wish to hear you music just the same, you will need the volume to be X + whatever volume the background is db.
b. IEM: Because IEMs have isolative qualities (yes, I know that's not a word), the Volume needed in a Noisy Environment = Background noise - Noise canceled by way of Isolation + X db.
Conclusion:
In quiet environments, [Assumption 3: Volume/loudness/db of music which we hear/hits our eardrums is the only thing that affects hearing loss], Headphones should be just as bad for your hearing as IEMs.
In noisy environments, the volume of the sound you hear out of your headphones will be more than the volume of your IEMs by the amount of sound that your IEMs isolate. So therefore, IEMS ARE SAFER.
There. I hope thats the final nail in the coffin of the IEM = BAD myth.
(Assuming my assumptions are right.
)
Chuwy