Think how confusing it would be if one minute you could understand verbal messages but the next moment words and sentences became incomprehensible. An inefficient processing of auditory events creates a “listening chaos," which results in a very frustrating misinterpretation of auditory information. Subtle background noise cannot be suppressed to allow for efficient processing of verbal input.

Incidence studies suggest that approximately 10 percent to 20 percent of our school children and 5 percent to 10 percent of adults are challenged by conflicting auditory messages in their everyday listening environments.

Researchers at Colorado State University’s Department of Electrical Engineering are investigating this phenomenon, which is called a central auditory processing disorder. Dr. Joan Burleigh is the director of the Center for Central Auditory Research (CCAR). Over 300 people nationwide are tested at the Center each year for central auditory processing disorders. CCAR is supported by the General Grand Chapter of the Royal Arch Masons, International.

"The typical individual we see has completely normal hearing. They can hear a pin drop. However, their problem occurs when more than one person is talking, or there is the presence of subtle fan noise, the shuffling of feet, or the crunching of paper," Burleigh says. “Minimal noise that a normal central auditory nervous system can suppress, a person with a central auditory processing disorder cannot. They have a poor filtering system that cannot suppress unwanted auditory input. Their system just becomes overloaded."

The Center works with a variety of special needs groups, including individuals with learning disabilities, reading problems, speech and language difficulties, autism, and head injuries. “The goals of this research include early identification of central auditory difficulties, a comprehensive management program, and ultimately the enhancement of speech for easier communication," says Burleigh.

The research at the Center is multi-disciplinary. Collaboration with electrical and mechanical engineers, computer scientists, audiologists, educators, psychologists, speech and language pathologists, and occupational therapists has added greatly to the research. “Having a multidisciplinary approach adds tremendous strength to the project," says Burleigh. “We believe that this approach allows us to proceed with cutting-edge technology that can be applied to enhance the quality of life for many special needs groups.”

Burleigh works closely with Dr. Michael Thompson, a former Colorado State faculty member who is now an associate professor in electrical engineering at The University of Texas-Pan American. Thompson, whose research area is digital signal processing (DSP), began working with Burleigh in 1989.

"Recent advances in DSP hardware have resulted in increased processing speeds that allow the implementation of real-time speech enhancement techniques that were previously not possible," says Thompson. Research by Burleigh and Thompson has shown that time-rate expansion, or the “slowing-down" of speech signals, has the potential to enhance intelligibility. By exploiting periods of silence that naturally occur in most speech applications, it is possible to produce high-quality speech rate expansion in near real-time without a significant delay.

“Our work will continue to focus on the enhancement of speech and to systematically prove that these techniques actually aid the communication process,” Thompson says. “At the same time, we want to be application-oriented and make sure that we can operate in a real-time format."

If a person is diagnosed with a central auditory processing disorder, Burleigh works on developing a management plan to facilitate improved auditory performance. “What we are looking at, in terms of the assessment process, is not only whether there is a central auditory processing problem." Says Burleigh, “but also what areas of the central auditory nervous system it impacts. We are also interested in the processing differences between ears.

‘Currently, our management plan is limited to the development of compensatory strategies and trying to suppress unwanted auditory information by the fitting of special filtered-earplugs," says Burleigh. “However, we have great hope for the future with technological advances in signal processing."

“Her research gives people hope that they can function in a normal world,” says Ginny Ward, whose child, John, was diagnosed as having a central auditory processing problem. “John has perfect hearing, but has significant difficulty understanding speech when other noises are present."

Another student Burleigh works with is autistic and has sensory integration problems. After being tested by Burleigh, he found that both ears were compromised. By wearing a special filtered-earplug in his poorer ear, his auditory system was better able to process incoming signals. “By reducing audio stimuli, it makes it easier to cope with other things," he says. "It is much less taxing on my system.”

In the future, Burleigh and Thompson expect that new discoveries from their research will lead to innovative methods for improving auditory signal enhancement. “We foresee in the near future that techniques will be improved and available for many individuals who have difficulty with interpreting auditory input. We also believe that research will be looking closer at the relationship between auditory function and other sensory modalities," Burleigh says.

Recently Burleigh was awarded for her work at Colorado State when she received the Royal Arch Mason’s Gold Medal for Distinguished Service in the Arts and Sciences. The award recognizes her over 20 years of research working with children and adults with central auditory processing disorders. Burleigh is not only the first female to win the award, she is also the first non-Freemason.