Hyperacusis is neither a disorder nor a disease. If by that term you mean "sound intolerance", that is a consequence of another thing.
If you have fullness and sound intolerance, most probably you have "ttts" (tensor tympani syndrome). The "fullness" you are experiencing is probably because your supposed tensor timpanis are tensed. The tensor timpani is a tiny muscle whose tendon is in contact with the malleus, a little bone which at the same time is in contact with the tympanic membrane. So when the TTs get tensed, the tympanic membrane gets tensed too, and the three ossicles and everything over there lose their harmony. The TTs should be relaxed, but "you" develop a bad habitude of tensing them. This causes discomfort with or without strong sounds.
But when the TTs are tensed and you hear certain sounds, especially sudden and with certain texture, and more especially if the source of the sounds is near you, the discomfort increases because you feel your ears fragile, that they are going to explode or broke, or something. It is an awful sensation, isn't it? And perception of these particular sounds could be distorted, or "distorted".
Your TTs are tensed because there is a signal originated in your brain that goes to the TTs to make them tensed. This operation is a more conscious operation that you think it is, and it is not dependent on sounds. On certain occasion, you could not feel "fullness", and then you hear certain sudden and strong sound near you and your TTs get tensed immediately. But if this happens is because your TTs weren't completely relaxed and the mechanism is still sensible. If the TTs are completely relaxed, and "you"/your brain completely forgets about the problem ("ttts"), I think it is impossible that the TTs get abnormally tensed (they could only get subtlety tensed), and so it is impossible to experience discomfort (of course, if the sound is too strong and near you, and the sound is repeated, it could cause the abnormal tension of the TTs, and that is precisely what happens in an acoustic shock).
So what you are now experiencing is this state of tensing all the time the TTs, a cumulative process of tensing and relaxing them continually. It is like a vicious circle.
The main motor of the tension is your consciousness about the problem. So you have to try to avoid that your TTs get tensed, try to control that. But the best way to do it is to forget about the problem. Basically you have to gradually get better and gradually forget about the problem.
Stress in general is not a cause. The problem is only specific. Certain emotions or thoughts could tense the TT system, like anger or obsessed thinking. But this depends on the person. Of course, I am talking when this habitude is installed, this doesn't happen in a person with healthy ears. If you realize there are certain emotions or attitudes that tense the TTs, try to avoid them. It is not by chance that depression, OCD, and other psychologic disorders are regularly found in people with "hyperacusis".
Another important thing to note is that apparently the TTs have slow-tonic fibers, and this would explain why, after they get tensed, it takes them some time to relax, which is really a downer. Because this make you more conscious about the problem, and so it could extend the period of tension even more. So you have to take a conscious and rigorous decision to quit the attention from the discomfort, and keep your mind busy with more interesting things than a muscle tensed in your middle ear.
It is okay, when your TTs are tensed and there are bothersome sounds, that you use earplugs, if you feel like it. You could use musician earplugs, which are easy to put in, and then take them out after some seconds, or minutes. Or cover with your hands. An earplug could be consider a temporary TT relaxer. I think you should avoid sounds that you feel are too strong for your ears, if they are repeated. How much is "too strong"? Well, only you know, you will learn. Be careful but not afraid.
Sound enrichment? If your TT mechanism is tensed, and you are at home watching a movie and it feels uncomfortable, you could play back simultaneously some broadband noise or rain sounds, or run water in the bathroom, whatever you feel relaxing. This reduces the contrast between the voices of the actors, for example, and the background noise. It is a possible temporary tool. But the ideal solution would be that you stop tensing the bloody TTs and you forget about all this.
P.S. There are other subtleties but I think my post was too long and boring already. You won't find this subject covered in this way in any medical article. Most articles are abstract or surrealist tales. This doesn't mean my description doesn't have some inaccuracies. Also, apparently there are no doctors or audiologists who understand about this in Planet Earth. You don't need them. Understand the problem and recover yourself.
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