Everybody on the planet has hearing loss except for babies and small children. Our upper frequencies gradually fade over time and nobody can escape this, so expecting everyone to have perfect hearing is unrealistic. The question then becomes: what hearing loss is considered noteworthy enough, and at what point is this hidden threshold crossed? There isn't a clear consensus, yet.
You're right about speech-in-noise being a better predictor for cochlea synaptopathy or hidden hearing loss, but this is still a relatively new concept and not much is really known about it. Some studies have indicated that people with tinnitus show a reduction in wave I during an ABR test and it's theorised that wave V increases as a compensatory response, which in turn increases the gain of one's central nervous system. This is a potential mechanism for tinnitus, but there is likely more to it than that from a strictly hearing loss point of view.
We know from Dr Shore's work that fusiform cells in the DCN can become hyperactive in brains that have tinnitus, and this can create synchronicity in other areas of the auditory cortex and brain which could create the perception of noise. However, Dr Rauschecker postulates that in order to perceive these noises our limbic system has to be malfunctioning, as he believes they are usually filtered out before they reach the higher functioning parts of the brain (where it can reach our conscious awareness). This essentially means that everyone with hearing loss has some form of tinnitus signal being generated within their brain, but only a certain percentage pick up that signal and tune into it. Once it is detected it seems incredibly difficult to "un-hear" it and fMRI studies (Fatima Hussain, for example) have shown that people with tinnitus tend to light up other areas of their brain (compared to non-tinnitus sufferers) under certain conditions. There also seems to be involvement from other areas of the brain relating to memory, behaviour, and emotion, like the caudate and putamen (dorsal striatum), nucleus accumbens, ventromedial caudate, and ventral putamen (ventral striatum) and the amygdala, hippocampus, thalamus, hypothalamus, etc, etc (again coming back to the limbic system). This suggests that the way in which one deals with their initial experience of "hearing" tinnitus may have more longterm ramifications. This is why many people advocate the importance of relaxing, de-stressing, and utilising things like CBT, mindfulness and meditation. That's not to say those things will definitely help, but calming one's CNS is always a good place to start; especially immediately after onset.
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