Tinnitus activity in the limbic system and autonomic nervous system, thus increasing tinnitus awareness and annoyance. There are two types of tinnitus: "subjective tinnitus" and "objective tinnitus". Tinnitus is usually subjective, meaning that there is no sound detectable by other means. Subjective tinnitus has also been called "tinnitus aurium", "non-auditory" or "non-vibratory" tinnitus. In very rare cases tinnitus can be heard by someone else using a stethoscope, and in less rare – but still uncommon – cases it can be measured as a spontaneous otoacoustic emission (SOAE) in the ear canal. In such cases it is objective tinnitus, also called "pseudo-tinnitus"
Firefighter lasting affects on the brain. A 2014 report from the National Fallen Firefighters Foundation found that a fire department is three times more likely to experience a suicide in a given year than a line-of-duty death. Mental stress of the job can lead to substance abuse and alcohol abuse as ways of coping with the stress. Another long-term risk factor from firefighting is exposure to high levels of sound, which can cause noise-induced hearing loss (NIHL) and tinnitus. NIHL affects sound frequencies between 3,000 and 6,000 Hertz first, then with more frequent exposure, will spread to more frequencies. Many consonants