Noise-induced and age-related hearing losses are widespread health problems. They are the most common forms of hearing loss seen in adult patients. This is a primary focus of Dr. Sharon Kujawa’s research efforts. Her work seeks to clarify how normal inner ear structures and functions are altered by aging and noise exposure, how vulnerability to these changes is shaped by an individual’s genetic background, and how these processes can be manipulated pharmacologically to reveal underlying mechanisms for treatment or prevention.

An area of current focus in Dr. Kujawa’s laboratory is the aging of noise-exposed ears. She has discovered an insidious process that begins acutely after noise, as a loss of communications (synapses) between sensory inner hair cells and cochlear neurons. Loss of the neurons themselves follows slowly, but ultimately reaches the same magnitude. These effects of noise immediately and permanently change the way the ear processes sound information, and they occur even when the exposure produces only temporary changes in hearing thresholds; i.e., for exposures previously thought to be ‘safe.’

Moreover, she has shown that such exposures dramatically accelerate the gradual loss of cochlear synapses and cochlear neurons otherwise seen with aging alone. This work has provided the first clear evidence that noise exposure continues to have damaging effects on the ear and hearing long after the noise has stopped.

Ultimately, noise exposure should be regulated, and its consequences diagnosed and treated, in ways consistent with improved understanding of underlying processes and pathology. Thus, this work informs efforts to develop better clinical tests and to identify effective pharmacologic therapies for these common forms of hearing loss, and should guide hearing conservation efforts aimed at better protecting the public health.

• Harvard Catalyst
• Eaton-Peabody Laboratories
• Speech and Hearing Bioscience and Technology (SHBT) Program