Research: Department of Otolaryngology

Hearing Research in the Department of Otolaryngology

The capacity to communicate is a skill that humans have superbly perfected. The ability to hear and to speak to one another provides us with qualities of life that are most important. The major aim of the basic hearing research laboratories of the Department of Otolaryngology at the University of Colorado Denver is to understand the diseases and disorders that affect our ability to hear, which represents one significant component of our capacity to communicate. Research provides the foundation and infrastructure for the subsequent clinical and applied studies fundamental to the improvement of clinical practice. Thus, identifying the causes of hearing impairment will enable us to devise effective treatments that make normal hearing possible.

Our research laboratories permit the study of hearing at three different levels of investigation. At the molecular level, experiments are aimed at understanding the workings of the fundamental elements of the inner ear's cochlea that provide the basis for the beginning stages of hearing. Specific studies are aimed, for example, at investigating the chemical signaling that occurs between one type of sensory transducer cell, called the outer hair cell, and the central auditory nervous system's descending efferent system. Other experiments are investigating the signals that cause the cochlea's sensory cells to die naturally as the ear ages. Together studies like these will contribute to our knowledge about, for example, the causes of tinnitus as well as age-related hearing loss, which is often referred to as presbycusis.

At the next level of analysis, a number of experimental models of hearing impairment and deafness are being developed that permit a more complete understanding of the changes that occur at the sensory-cell and molecular levels when the ear is assaulted by potentially damaging external agents. Such conditions consist of noise-induced hearing loss as well as the hearing impairment associated with the ototoxic effects of certain types of antibiotics and anti-tumor drugs. Other experiments are investigating the role of ischemic factors in producing such impairments as the hearing loss associated with acoustic tumors, Meniere's disease, sudden hearing loss, and age-related presbycusis.

Lastly, at the final level of examination, studies are being conducted on both normal-hearing humans and hearing-impaired patients that are aimed at developing better tests for diagnosing hearing problems and for monitoring the efficacy of treatment. The majority of this research is focused on devising new tests using a response measure known as evoked-otoacoustic emissions, which permit ear function to be examined noninvasively and objectively, in a thorough and rapid manner. These experiments range from identifying particular patterns of abnormal activity that provide important details concerning the precise anatomical locus of a hearing difficulty, within the peripheral portion of the auditory nervous system, to providing an intraoperative monitor of the ear's status during surgeries aimed at removing a tumor from the auditory nerve, and to the screening of ear function in newborn infants that are only a few hours old. In combination, these research projects use methodologies that range from investigating single molecules that make up the messenger chemicals that underlie our hearing ability in experimental models of deafness to studying the basis of normal hearing in human subjects, as well as the difficulties experienced by hearing-impaired patients.