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"
Tinnitus masker tinnitus sounds and background sound. More advanced software based tinnitus maskers can use a combination of natural and synthetic sounds or a filtered noise generator tailored to mask the specific frequencies at which the tinnitus signal is experienced. Some sufferers require masking at all times. These people may employ wearable hearing aids which amplify ambient sound, generate low level wide band sounds such as white noise, or combination devices that mix both functions into one device. A standard hearing aid may be used for tinnitus masking; the tuning and amplification characteristics are different than when one is used in compensation