East Michigan News

Sarah Grinn will measure numerous ears over the next five years to enhance hearing aid effectiveness.

Grinn, a faculty member of Central Michigan University’s communication sciences and disorders department, is collecting data on the size and shape of the outer ear to refine the programming and safety of hearing aids.

“Hearing aids are programmed using two measurements,” Grinn said. “One measurement is from the inner ear (the sensitive hearing organ that responds during a hearing test), and one measurement is from the outer ear (the part a doctor can look inside of, which funnels and amplifies sound into the inner ear).” Doctors of Audiology (Au.D.) use both measurements to precisely program hearing aid amplification for patients.

While inner ear measurements can be obtained through online tests or features like those in newer Apple iPhones, outer ear measurements require clinical training and specialized equipment available only to audiologists. The cost of prescription hearing aids, ranging from $4,000 to $7,000, drives some individuals toward more affordable alternatives.

Over-the-counter hearing aids ($300-$600) offer a cheaper option but come pre-programmed with a one-size-fits-all approach based on an average adult male's ear size. This can lead to mismatches in amplification for those whose ears differ from this average.

Grinn’s research aims to address this issue by establishing averages for outer ear sizes and shapes across different demographics. Her team is currently measuring 300 adults in six height categories and plans to complete this phase within a year before moving on to children's ears.

The subsequent phase involves recruiting 336 children aged between 3 months and 15 years. Each child's outer ears will be measured annually for four years. Unlike adults, children's outer ears change as they grow, affecting how amplification works through them.

“Over-the-counter hearing aids aren’t currently available for children,” Grinn noted. All pediatric hearing aids are prescribed by audiologists who often rely on age-based estimates due to children's inability to sit still during measurements. This can result in inaccurate amplification settings.

“This research will improve audiologist-prescribed hearing aids for children and over-the-counter hearing aids for adults,” Grinn said.