The results of the research, reported in Nature, indicate that this masking of external sounds-a phenomenon the researchers call a "line busy" signal-leads to a significant hearing loss that is completely different from that caused by damage to sensory cells.

Nicholas Powers, UB assistant professor of communicative disorders and sciences, and Richard J. Salvi, UB professor of communicative disorders and sciences, said many human ears emit low-intensity sounds that are not noticed by most listeners and do not affect hearing. However, these sounds are very strong in a small percentage of individuals and are associated with noticeable hearing loss.

The researchers, members of the Center for Hearing and Deafness at UB, have found these high-intensity sounds in 15 chinchillas and conducted extensive measurements on two animals. The sounds being emitted from these two animals were so loud that they could be heard by the researchers when the animals were taken into a quiet room.

While it has been known for years that the ears of some humans and animals can produce sound (objective tinnitus), it was thought that these inner-ear vibrations did not reach the brain. The UB research team is the first to determine that these sounds actually are transmitted into the brain by way of the auditory nerve.

Other members of the research team were Jian Wang, a research scientist, and Chun-Xiao Qiu, a doctoral student, both in the UB Department of Communicative Disorders and Sciences.

-Sue Wuetcher, News Bureau Staff