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Most hearing aids on the market today are designed to mimic what happens in our inner ear - specifically the amplifying role of the outer hair cells.

However, the lab of Laurel Carney, Professor of Biomedical Engineering, is studying what happens beyond the inner ear - in the complex network of auditory nerve fibers that transmit the inner ear's electrical signals to the brain, and in the auditory center of the midbrain, which processes those signals.

Therein lies the key to creating hearing aids that not only make human speech louder but clearer, Carney believes.

An important focus of her research uses a combination of physiological and behavioral studies, and computer modeling, to study the 30,000 auditory nerve fibers on each side of our brain that transmit electrical signals from the inner ear. Critical to this is the initial transduction of mechanical energy to electrical signals that occurs in the inner hair cells of the inner ear's organ of Corti.

This is critical for shaping the patterning of responses in the auditory nerves, and the patterning of those responses at this first level, where the signal comes into the brain, has a big effect on the way the mid brain responds to the relatively low frequencies of the human voice, Carney explained.

In people with healthy hearing, the initial transduction results in a wide contrast in how various auditory nerve fibers transmit this information. The responses of some fibers are dominated by a single tone, or harmonic, within the sound; others respond to fluctuations that are set up by the beating of multiple harmonics, Carney said. In the mid brain, neurons are capable of assimilating this contrast of fluctuating and nonfluctuating inputs across varying frequencies. They begin the process of parsing out the sounds of speech and any other vocalizations that involve low frequencies. A better understanding of how this process works in the midbrain, Carney believes, could yield new strategies for designing hearing aids.

A lot of people have tried to design hearing aids based just on what is going on in the inner ear, but there's a lot of redundancies in the information generated there. We argue that you need to step back and, from the viewpoint of the midbrain, focus on what really matters. It's the pattern of fluctuations in the auditory nerve fibers that the midbrain responds to. The sort of strategies we're suggesting are not intuitive. The idea of trying to restore the contrast in the fluctuations across different frequency channels has not been tried before. The burden is on us to prove that it works, she added.

To that end, Carney works closely with Joyce McDonough, Professor of Linguistics, in exploring how auditory nerve fiber transmissions play a role in coding speech sounds. Her lab also works closely with that of Jong-Hoon Nam, Assistant Professor of Mechanical Engineering and of Biomedical Engineering, whose inner-ear studies were described in this newsletter last week. Carney shares what her lab is learning about the interface of auditory nerve fiber signaling with the brain, and in return, we try to include in our models a lot of the nonlinear properties of the inner ear that he (Nam) has been working on. By interacting with his lab, we hope to continue to modernize our model as he discovers more, Carney said.

Laurel Carney, a professor of Biomedical Engineering, has been recognized for her work by the premier scientific organization in the field of acoustics. The Acoustical Society of America has awarded Carney the William and Christine Hartmann Prize in Auditory Neuroscience.

It's truly a great honor to receive an award created by Bill and Christine Hartmann, two of my role models, said Carney. I welcome the challenge to emulate their life of discovery, presentation, publication, service, and education throughout the world.

William and Christine Hartmann established the award with a donation to recognize and honor research that links auditory physiology with auditory perception or behavior in humans or other animals. William Hartmann is a physicist, psychoacoustician, and former president of the Acoustical Society of America. His contributions to the field involved pitch perception, signal detection, modulation detection, and the localization of sound.

In her research lab, Carney is working to better understand how the brain translates sounds into patterns of electrical impulses. By studying physiology, human hearing, and computer models, Carney hopes to learn how the brain distinguishes sounds in noisy environments and why even a small degree of hearing loss can lead to major problems. Her ultimate goal is to develop effective strategies to help people who have experienced hearing loss.

Carney earned her M.S. and Ph.D. degrees in electrical engineering at the University of Wisconsin-Madison. She was an associate professor of biomedical engineering at Boston University and professor of biomedical engineering at Syracuse University before joining the faculty at the University of Rochester in 2007, where she serves as professor in three departments—biomedical engineering, neurobiology and anatomy, and electrical and computer engineering.

Laurel H. Carney has been awarded the William and Christine Hartmann Prize in Auditory Neuroscience by the Acoustical Society of America (ASA). The award was presented at the 169th meeting of the ASA on 20 May 2015 in Pittsburgh, Pennsylvania.

The William and Christine Hartmann Prize in Auditory Neuroscience was established in 2011 through a generous donation by Bill and Chris Hartmann to the Acoustical Society of America to recognize and honor research that links auditory physiology with auditory perception or behavior in humans or other animals.

The Acoustical Society of America provides an important scientific home for researchers pursuing questions related to sound and hearing. This group has positively shaped many of our careers, especially by providing access to an incredible group of mentors and role models. Receiving an award created by Bill and Christine Hartmann, two of my own role models, is truly a great honor. This award presents a challenge for me to emulate their life of discovery, presentation, publication, service, and education throughout the world, said Carney.

The goal of Dr. Carney's research program is to understand how the brain hears. The initial response of brain cells to sound is a complicated pattern of electrical pulses, a pattern that is modified and interpreted by millions of cells in many parts of the brain. Studies of physiology, human hearing, and computer models are combined to understand how this process works in listeners with normal hearing, so that an answer can be found to the question: How is the brain so good at hearing in noisy environments? Another goal is to understand why only relatively small amounts of hearing loss cause significant problems. Why does background noise (such as that in a busy restaurant) become so problematic for people with hearing loss? Answers to both of these questions will lead to better strategies for aiding listeners with hearing loss.