We have different reasons for using headphones actually. Some of us use these small devices as a means of relaxation while doing strenuous work, like working out in the gym. Some may use these devices because they are in a public place that promotes some form of decency and politeness of not being too publicly loud. Others may even use them because of the need of keeping whatever they are listening to for themselves, not wanting to share any information which might prove quite private.
However, many of us do not know or are not actively aware that using these small wonders of technology can actually affect our hearing in a way that they may be caused by physiological impairment.
We may have our hearing affected due to the misuse of headphones as we try to drown out the noise in the environment, but actually only substitute another and much more acceptable form of sound with the same level.
Everyday, we hear all sorts of sounds, some of them louder than the rest, while some are outright appalling and unacceptable to our perception. These may be sounds that are too loud for our ears to perceive or because these bring about awful thoughts and ideas which we personally abhor and detest. Even when we sleep, our ears are able to detect sounds as they are, but the mere fact that our minds are consciously inactive would not allow us to be aware of sounds as distinct as they should be when we are awake. Nevertheless, our eardrums are still able to detect these sounds and would still be subject to damage not based on our conscious perception but to the raw sound level that reaches our ears.
This is most evident whenever we accidentally fall asleep with our headphones on. Having them plugged into our ears as we fall asleep pose a great risk on abusing our eardrums without rest from the constant vibrations brought about by the sound focused straight down our ear canals. Imagine a 6-hour sleep at least with constant barrage of sound to our ear. It would have been all right if the sound has not been too loud beyond normal threshold. Safe levels of sound would be around 60 to 70 decibels, roughly equivalent to a person playing the piano. Exposing our ears in this manner would require only a progressive diminishing amount of time of exposure as the decibel rate goes higher.
It is even much healthier to be aware of the sounds in the environment rather than isolate yourself with your own preferred sound coming from the headphones. In comparison, a similarly produced sound level produced from an environmental stimulus is better and safer than that coming from the headset mainly because the former would still have to travel a long distance towards the ear, and much of the vibrations would have been dispersed as it hits the outer ear.
Furthermore, there would have been already waste in the amplification level of sound as it travels through the media, which in this case is the atmosphere. By the time the sound reaches the eardrums, the sound would already have been lessened in effect, and thus the eardrum would not have to take the whole brunt if ever the same level of sound came from the latter.