I was an MTR operator at a Nike-Herc. battery from ‘68 to ‘71. The electronic noise was constant.
However, I didn’t notice the tinnitus until about 1990 when, as plate ump, I was hit in the face mask by a pitch ball. It has been constant since then.
Head injuries, concussive type injuries, loud noises, illness, medications...tinnitus can have multiple etiologies even in the same patient.