Phantom noises, that mimic ringing in the ears associated with tinnitus, can be experienced by people with normal hearing in quiet situations, according to new research.

The Brazilian study, which consisted of 66 people with normal hearing and no tinnitus, found that among subjects placed in a quiet environment where they were asked to focus on their hearing senses, 68 percent experienced phantom ringing noises similar to that of tinnitus.

This is compared to only 45.5 percent of participants who heard phantom ringing when asked to focus on visual stimuli and not on their hearing, and 19.7 percent of those asked to focus on a task in a quiet environment.

The authors believe that these findings show that with regards to tinnitus, the role of attention to symptoms, as well as silence, plays a large role in experience and severity.

Tinnitus, an auditory perception that cannot be attributed to an external source, affects at least 36 million Americans on some level, with at least seven million experiencing it so severely that it interferes with daily activities.

The disorder is most often caused by damage to the microscopic endings of the hearing nerve in the inner ear, although it can also be attributed to allergies, high or low blood pressure (blood circulation problems), a tumor, diabetes, thyroid problems, injury to the head or neck, and use of medications such as anti-inflammatories, antibiotics, sedatives, antidepressants, and aspirin.

Full details of the study are published in the January 2008 edition of Otolaryngology -- Head and Neck Surgery.