Hearing and Cognition: Cutting Edge Hearing Aid Research
The long-established protocols for testing the effectiveness of hearing aids are changing as researchers seek to remedy the relationship between hearing impairment and cognitive development. The findings of the latest research in hearing science are intriguing. The potential outcome the development of a multi-dimensional hearing device designed to not only improve the wearers ability to hear, but to also improve the ability to understand.
Hearing and Cognition
The Starkey Hearing Research Center, under the direction of recognized authority, Brent Edwards, PhD, has been conducting research in conjunction with the University of California, Berkeley on the relationship between hearing impairment and cognitive development.
As Edwards explained during a recent interview, The brain hears what it wants. Each individual will interpret sound differently based on cognitive factors. If you ask four people to listen to a piece of music, youll get four different interpretations based on cognitive factors alone. Each listener brings to the hearing experience a lifetime of cognitive development that is an important factor in hearing accurately.
The fact is, hearing is just the first step in a complicated process. Hearing is transducing acoustic signal(s) to physiological information, according to Edwards.
The process continues as sound is translated and relayed to the cognitive system of the brain. In the brain, sound-based information goes through a series of steps. The first is listening, described as selecting information with attention and effort. This also includes filtering out non-useful noise ambient sound in a noisy restaurant, for example.
The next cognitive step is comprehension, or interpreting contextual linguistic and grammatical information, Edwards stated during his recent presentation, The Intersection of Hearing Science and Hearing Technology, made before the American Association for the Advancement of Science (AAAS).
The final step in the cognitive process is reacting, which includes storing sound information, e.g. human speech, in ones memory, reasoning and responding in an appropriate manner to the sound.
So, in fact, hearing, which is caused when sound waves reach the ear drum, is just the first step in best utilizing sound-based sensory input. Three additional steps take place once the information has been translated and delivered to the brains cognition system. In the brain, sound-based input is filtered, examined, analyzed and serves as the stimuli for appropriate reaction from the listener.
The thesis behind the research is simple. Individuals with hearing impairments also experience cognitive developmental delays related directly to the hearing impairment. As the Dr. Edwards at Starkey explained, The brain has to spend more time, energy and space to focus on the act of listening in hearing impaired people. Because more of the brain is actively involved in the hearing process, cognitive development is often slowed.
The Starkey Hearing Research Centers studies have shown that diminished cognitive development leads to poor memory, lack of problem-solving skills, and other non-hearing related issues. The conclusion, at this stage, is that improved hearing devices will someday improve hearing and understanding.
Hearing Aid Engineering and Audiology
In the past, the engineering of hearing devices has focused primarily on two hearing needs: sound quality and speech understanding. With the advent of digital technology, hearing aids have been improved to deliver higher quality sound and a more natural hearing experience for the wearer. However, thus far, advancements in hearing aid technology have focused on higher quality sound, improved speech recognition, and automation to simplify routine device functions such as automatic volume control and improved microphone directionality.
Audiologists have focused patient testing to hearing functions. Traditionally, cognitive development issues have been left to other professionals, even though the relationship between hearing impairment and cognitive development has been recognized for some time. Today, the audiology community has added a new dimension to measuring the effectiveness of hearing devices improvement in cognitive ability.
From Engineering to Science
Engineering has taken hearing aid technology to its current high standards. However, even though 91% of all hearing devices are digital, offering improved sound quality, Edwards, is quick to point out that hearing impairments still lead to slowed speech communication, diminished access to the environment and others, limited hearing and interpretation of non-speech sounds, the loss of spatial hearing and selective attention issues that impact cognitive development.
In the past, the hearing aid industry defined hearing loss in terms of audiogram results. Hearing loss has been treated uniformly with universal treatments that may or may not benefit individual hearing aid users. Today, Edwards explained during his presentation, the industry has changed its views, defining hearing loss by mechanism (cause of impairment) and placing more emphasis on the individuality of the impairment, the patient, and therapies.
This expert believes that the research conducted by the Starkey Hearing Research Center and UC Berkeley will lead to more individualized treatments designed to address the specific needs of the wearer.
The hearing aid industry has focused most of its engineering resources on improving sound quality, automated convenience, and improved speech recognition. The improvements made in these areas came through technological advances based primarily on digital technology.
And while these improvements are certainly welcomed, they dont address the problem of slowed, hearing-related cognitive development, a process that includes selective listening, recognition and reasoning, and finally reaction.
Thus, there is a need for hearing science to take a more active role in the development of the next generation of hearing aids devices that not only improve hearing, but also better facilitate the cognitive processes once sound input is delivered to the brain.
Indeed, hearing aid technology has made major strides in the past decade and we can anticipate that improvements to existing devices will continue to be made. We can also look forward to technological advancements that improve cognitive activities in hearing impaired individuals.
With hearing science and technology joining in a stronger collaboration, we can expect to see devices capable of delivering improved sound quality, improved speech recognition, and improved functionality to increase cognitive development in hearing aid wearers.
For more information on Starkey Laboratories, Inc., www.starkey.com.