It probably is there all the time, I do recall a slight hiss in perfect silence even as a child, it's just that it seems to have gotten permanently louder for me. There was a discussion in this thread already (but it was easy to miss because of how fast the thread is growing). I used MXE on and off for nine months before the tinnitus finally set in permanently, so it's not a matter of simply becoming aware of it. It gets louder during the trip, but had always faded to inaudibility before. Now it gets much louder during a trip, and doesn't fade all the way away afterwards. There seems to be innumerable drugs/conditions associated with acquiring tinnitus, so maybe it wasn't the MXE at all. Individual susceptibility to various tinnitus causing drugs seems to vary radically. Since the only other person in this thread who had experienced persistent tinnitus after MXE use discovered it was due to an ear infection, even if my tinnitus does owe to MXE use I wouldn't say MXE is especially likely to cause permanent tinnitus in the average user. It's just that it clearly does cause temporary tinnitus in many, including me, and so I think it's the most likely source of my own seemingly permanent tinnitus, too.
I'm trying the "Tinnitus Tamer" audio software to see if it stops or lessens the sound. It might be worth a shot for anyone else who's got it, IDK.
Psood0nym, can you describe the nature of the sound you are hearing? Does it manifest itself in other ways, such as visual or other sensory overlap? Also, does it increase when you are taking a shit, or when mentally and physcially exciting thoughts enter you mind? I have tinnitus, but in my case it wasn't caused by MXE. The background noise that I am hearing was exacerbated by 5-HT psychedelic use.
It seems the 5-HT psychedelics cause a temporary auditory phenonmenon that goes hand in hand with the visual and mental phenomenon, and which can develop in to a semi-permanent state with frequent high dose tripping. It seems to be the auditory counterpart to the visual phenomenon which people report as "HPPD". Ever since some intense experiences last year with some of the 2Cs - in combination with cold-turkeying from a long-term diazepam habit - I have had an omnipresent aural signature which I would describe as sounding like a "digital jungle" in high pitch. This has changed in character somewhat over the course of this year, and is much quieter than it was when I came off the diazepam, but it increases in loudness when I am coming up on a psychedelic. When I am peaking it is overtaken by the auditory phenomenon of the experience.
I can hear the sound now as I sit at my (loud) computer typing this, yet it is not caused by the sounds of the electrics or mechanics in the machine. I can hear it equally if I am taking a shit in my quiet bathroom, or anywhere else where there is a relatively low noise floor.
It also feels like a perfectly natural sound, as if it is meant to be there. It sounds like an intergral part of reality that my brain had tuned out before I was re-awakened to it. I feel there is probably an infinite spectrum of these frequencies, available to all senses, but our brains act like a bandpass filter on a synthesizer such as to focus on just the frequencies that our senses need to pickup in order to construct a reality that enables us to survive and reproduce.
When I am tripping on a very heavy dose of a phenethylamine, I can feel the sound ramp up in intensity and it becomes almost synaesthetic in it's texture. The sound sweeps through my psyche and it feels very healing. I can feel the very same frequencies and harmonics resonating through my body. When this happens I know I am on the way to profound ego-dissolution in the peak.
Although I found ketamine to sometimes cause a swell of tinnitus on the comeup, with intense 'hole' doses, I have yet to experience an increase in tinnitus with MXE, but I have only used it twice. Again, it accompanies the very sensation of falling in to the trip and merges with that sensation, in a sense.