Tinnitus emissions (SOAEs), which are faint high-frequency tones that are produced in the inner ear and can be measured in the ear canal with a sensitive microphone, may also cause tinnitus. About 8% of those with SOAEs and tinnitus have SOAE-linked tinnitus, while the percentage of all cases of tinnitus caused by SOAEs is estimated at about 4%. Some people experience a sound that beats in time with their pulse, known as "pulsatile tinnitus" or "vascular tinnitus". Pulsatile tinnitus is usually objective in nature, resulting from altered blood flow, increased blood turbulence near the ear, such as from atherosclerosis or venous
Tinnitus masker amplitude determines the degree of masking achieved. In some cases, the required masking amplitude is so high as to cause discomfort to the user of the sound generator, and the tinnitus is therefore considered unmaskable. The frequency and other characteristics of tinnitus can vary over time, and the shifts can be temporary or permanent. They may also be cyclical. Therefore the optimal tinnitus mask may need to be adjusted periodically, within days, hours, or even minutes. So a fixed recording (i.e. CD, DVD or audio file) of a tinnitus mask is not a very efficacious application. There are also safety