Can Better Hearing Aids Help You Think Better?

October 2009

Editor: Scientists at Berkeley and Starkey Labs are studying the effects of various hearing aid features that improve speech understanding in noisy environments in an attempt to demonstrate that having an easier time understanding speech leaves more brain processing power for cognitive tasks! Here's the story.

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The Starkey Hearing Research Center, Berkeley, a division of Starkey Laboratories Inc, Eden Prairie, Minn, in collaboration with the University of California at Berkeley, has announced the publication of a seminal research paper on the impact of hearing aid technology on listening effort, in a statement released by the company.

"Objective Measures of Listening Effort: Effects of Background Noise and Noise Reduction," was recently published in the Journal of Speech, Language, and Hearing Research. The collaborating team includes Anastasios Sarampalis, PhD, and Professor Ervin Hafter, PhD, from the Department of Psychology, University of California at Berkeley; and Sridhar Kalluri, PhD, and Brent Edwards, PhD, from the Starkey Hearing Research Center.

"We are very proud of the results of our collaboration with the University of California at Berkeley," said Edwards, in the statement. "Hearing loss impacts not just communication but cognitive function as well, and this research suggests that hearing aid technology can both improve speech understanding and reduce the cognitive effort necessary to understand speech in noisy situations. We hope this study moves future hearing aid research toward measuring outcomes beyond audibility to look at cognitive benefits as well."

Hearing-impaired individuals understand speech in quiet almost as well as people with normal hearing, but in background noise, hearing-impaired people have a hard time understanding speech - even with the help of hearing aids, says the statement. In addition, it says, people with hearing loss are typically more mentally fatigued than people with normal hearing after listening to speech in noisy situations, suggesting that hearing loss results in greater cognitive effort to understand the speech in noise. This research looked at the effect of noise reduction and directional microphones on speech understanding and listening effort.

The study tested the following hypothesis: the positive effects of noise reduction and directional microphones could be to help reduce the cognitive effort used to receive and understand speech, making additional cognitive resources available for other tasks. People with normal hearing participated in two dual-task experiments--one reporting sentences or words in noise at various signal-to-noise ratios (SNR), and the other either holding words in short-term memory or responding in a complex visual reaction-time task.

SNR improvements provided by hearing aid directional microphones resulted in better performance in speech understanding and in the secondary task, indicating that the SNR improvements reduce listening effort. Noise reduction had no positive effect on speech recognition and understanding, but it led to better performance on the memory and visual secondary tasks at low SNRs.
The conclusion that can be drawn is that noise reduction and directional microphones reduced listening effort and freed up cognitive resources for other tasks, said the statement.

"While no one has found compelling evidence that noise reduction (NR) in a hearing aid improves speech reception, the results here clearly show an effect on performance in a second task," said Hafter. "Costs in performance like this when the perceiver must share attention between channels has long been discussed in terms of attentional effort, a phrase that describes use of a limited cognitive resource.

"From that perspective, NR, by reducing the effort needed to do the auditory task in high noise, allowed its application to the visual," he said. "This strongly suggests that dual-task methodology be applied in testing the efficacy of any algorithm designed for hearing and, perhaps, other devices used in auditory communication. From this perspective, these data seem to fit with the growing concern that the danger of cell-phone usage goes far beyond the business of mechanically operating the phone and focuses on the attentional overload associated with holding an intense, informational conversation."