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 wide band white or pink noise, narrow band white noise, a notched soundfield, frequency or amplitude modulated sound, intermittent pulsed sound, or other patterned sound. Temporally patterned sound may be more effective than white noise or background music in masking tinnitus. Studies have found that bandpass maskers are less annoying than pure tone maskers, that the annoyance rating of bandpass maskers is proportional to bandwidth, that intermittent maskers were more annoying than continuous ones, and that control over the center frequency and bandwidth was important in minimizing the annoyance of maskers. In addition to the spectrum of masking sound, the