Why NIDCD Supports Hearing and Balance Research
Hearing and balance disorders decrease quality of life, cross all ethnic and socioeconomic lines, and impose a significant social and economic burden upon individuals, their families, and the communities in which they live. Millions of Americans experience a hearing or balance disorder at some point in their life, especially as young children or older adults. Common examples include otitis media (middle ear infections), noise-induced hearing loss, tinnitus, age-related hearing loss, dizziness, and vertigo. Approximately 36 million American adults report some degree of hearing loss1 and almost eight million adults report a chronic problem with balance.2 In addition, two to three out of 1,000 babies born in the United States each year have a detectable hearing loss3, 4 that can affect their speech, language, social, and cognitive development.
Mouse models of hereditary hearing impairment have been and continue to be instrumental in mapping and cloning many of the gene mutations that contribute to deafness. They are also being used to study how gene mutations affect protein function and result in deafness, and to test therapeutic approaches to treat or prevent hearing loss. These models allow researchers to study genetic factors involved in hearing loss and the development and maintenance of the human ear. In addition, mouse models have allowed scientists to directly examine auditory sensory cells and to characterize the inner ear’s response to sound. Recent research has identified some of the cellular processes that contribute to hair cell damage and death, allowing future studies that may determine the inner ear’s response to mechanical and chemical trauma.
Otitis media (OM), or middle ear infection, is a condition that affects most young children prior to three years of age. Repeated episodes of OM can contribute to hearing loss and a possible delay in language and cognitive skills development. NIDCD research is improving our understanding of susceptibility and pathogenesis of OM. In the future, this research might define immune pathways for effective middle ear protection by vaccines.
Tinnitus, or ringing in the ears, is a hearing disorder that affects approximately 25 million Americans, both those with and without hearing loss. Its severity can range from a mild condition, which requires no intervention, to a severe debilitating disease with significant emotional, social, and economic impact. NIDCD research aims to determine the neural basis of tinnitus, and to develop effective interventions for affected people.
Technology Interventions for Hearing Loss
People with mild to moderate hearing loss often benefit from using a hearing aid, and many with severe to profound hearing loss benefit from being fitted with a cochlear implant. Advances in both hearing aid and cochlear implant technology are improving the ability of both types of devices to treat many people with various types of hearing loss. For example, individuals may be fitted with hearing aids or cochlear implants on both ears instead of only one ear to improve sound localization and discrimination. In recent years, some people with residual hearing for low-frequency sounds have received both a cochlear implant, to aid them in hearing higher-frequency sounds, and a hearing aid to allow them to take advantage of their residual low-frequency hearing. In many cases, this strategy results in a significant improvement in hearing performance over the use of only one device.
The inner ear contains the vestibular system, which helps us maintain our balance and navigate. Vestibular disorders lead to dizziness, vertigo, nausea, migraines, and various forms of postural instability. Dysfunctions of the vestibular system can occur independently or with a hearing loss. NIDCD research is supporting the development of safer, better tolerated, and more effective pharmacological treatments for vertigo. Additional research is attempting to develop vestibular prosthetic devices and minimally invasive surgery techniques to control imbalance and vertigo while preserving hearing and other functions.
The Hearing and Balance Program
The NIDCD Hearing and Balance Program encompasses over half of NIDCD’s portfolio. To study normal and disordered functions of the auditory and vestibular systems, the NIDCD employs a wide range of research approaches such as molecular genetics, cellular biology, animal models, biomedical imaging, nanotechnology, psychoacoustics, and structural and functional biology. The NIDCD supports research that will lead to improved treatments for, and prevention of, hearing and balance disorders.