In the advance online edition of Nature on January 12, 2011, the researchers reported that the number of neurons tuned to the high frequency had jumped by 79% compared to control rats. The scientist then tested 2 different tones in a second group of rats but stimulated the vagus nerve only for the higher one. The neurons tuned to the higher tone increased by 70%, while those tuned to the lower one decreased in number. This showed that the tone alone wasn’t enough to initiate the change; it had to be accompanied by VNS.
Tinnitus is the name for hearing a sound that is not physically present in the environment. Some researchers have also described tinnitus as a “phantom auditory perception.” People with tinnitus most often describe it as ringing, buzzing, cricket sounds, humming, and whooshing, although many other descriptions have been used. To hear some sound samples access the American Tinnitus Association website, where they have put together files of different manifestations of tinnitus to listen to for education purposes.
Atherosclerosis. With age and buildup of cholesterol and other deposits, major blood vessels close to your middle and inner ear lose some of their elasticity — the ability to flex or expand slightly with each heartbeat. That causes blood flow to become more forceful, making it easier for your ear to detect the beats. You can generally hear this type of tinnitus in both ears.