Our ability to communicate is our tether to the social world. For most people, hearing difficulties begin the same way: there’s an inability to follow conversation in a noisy room. Perhaps you can hear that someone is talking. You just can’t make out what they’re saying.
This “suprathreshold” difficulty, where the sounds are loud enough to detect but the brain cannot extract meaningful information from them, affects more than 20 percent of Americans over the age of 12.
It affects not only those with measurable hearing loss but also many whose hearing tests come back normal—including some older adults, veterans and athletes with concussion histories, and workers exposed to occupational noise in settings like the steel mills, mines and farms across Western Pennsylvania.
These patients fall through the cracks because the standard clinical toolkit was not built for this problem. The audiogram measures the ability to detect soft sounds, but not what happens when a patient can hear a sound but cannot understand it. And the blanket label “sensorineural hearing loss” obscures a spectrum of underlying pathologies, each of which may demand a different treatment.
A trio of researchers in Pitt’s Department of Communication Science and Disorders (CSD) is working to change that. Assistant Professors Aravind Parthasarathy, Hari Bharadwaj and Samantha Hauser are building the foundation for precision audiology, a model in which every patient receives an individualized hearing profile as specific and actionable as any other personalized medicine approach.
“There are many factors at play when it comes to hearing loss,” says Parthasarathy. “Typically, the components of the ear and brain work together to allow a person to hear. But when there are changes in the ear or brain, or changes in what the ear conveys to the brain, it can be difficult to diagnose exactly where the hearing loss occurs.”
As director of the Translational Auditory Neuroscience Lab, Parthasarathy has adapted electroencephalography (EEG)-based technology so it can capture the brain’s electrical response to sound at every level of the auditory pathway, from the cochlear nerve to the cortex. Recently published in Nature Communications Biology, the tool records these responses in 15 minutes, giving clinicians a way to see not just whether a patient detects a tone, but where the signal breaks down.
Bharadwaj, vice chair for research in the CSD department and director of the Systems Neuroscience of Auditory Perception Lab, has uncovered a surprising culprit behind these difficulties: the cochlea’s frequency map going awry. “When this map becomes distorted after some forms of hearing damage, low frequency sounds overwhelm the high-frequency speech cues critical for conversation,” says Bharadwaj. “The effect persists even with hearing aids, because amplification cannot restore disordered frequency tuning.”
He adds that there are new diagnostic tests and evaluations that will eventually help more people to hear better. “Building a personalized profile for each patient is essential to determining the best treatment pathway. This helps identify, for example, who may not benefit from traditional hearing aids and needs newer signal-processing approaches instead who has the specific type of inner-ear damage that emerging pharmacological treatments are designed to target; and who might benefit most from brain training.”
“Current hearing tests don’t give you the full picture,” adds Hauser, director of the Precision Audiology and Clinical Translation Lab. A former practicing audiologist, she uses coordinated testing in animal models and human subjects to build a diagnostic battery that assigns each patient a cochlear damage profile rather than a one-size-fits-all label, guiding clinicians toward the intervention most likely to help.
“We can’t underestimate the importance of hearing,” continues Hauser. She says many people overlook their own hearing loss, but this can have a significant psycho-social impact.
“When someone can’t hear, they become more and more disengaged with those around them,” says Parthasarathy. “There is evidence that untreated hearing loss leads to depression, risk of falling and cognitive decline.”
According to Bharadwaj, there needs to be a better awareness that hearing health is part of a person’s overall wellbeing. He believes their research is a start in the right direction.
The team’s recently awarded $2.9 million grant from the National Institutes of Health uses multidisciplinary techniques to develop individualized profiles that predict real-world outcomes. The work draws on a registry of over 37,000 individuals with hearing loss under the age of 65 provided by the Pitt Clinical and Translational Science Institute. With gene therapies and AI-powered hearing aids on the horizon, knowing which pathology to target has never mattered more. At Pitt, this future is being built.
