Trent Consultants News The vast majority of school-aged kids can focus on the voice of a instructor amid the cacophony of the typical classroom thanks to a brain that automatically focuses on relevant, predictable and repeating auditory information, according to new research from Northwestern University.
But for kids with developmental dyslexia, the teacher’s voice might get lost in the background noise of banging lockers, whispering children, playground screams and scraping chairs, the researchers say. Their study appears in the Nov. 12 issue of Neuron.
Recent scientific studies recommend that kids with developmental dyslexia — a neurological disorder affecting reading and spelling skills in 5 to 10 percent of school aged kids — have difficulties separating relevant auditory information from competing noise.
The research from Northwestern University’s Auditory Neuroscience Laboratory not only confirms those findings but presents biological evidence that kids who report problems hearing speech in noise also suffer from a measurable neural impairment that adversely affects their capability to make use of regularities in the sound environment.
“The capability to sharpen or fine-tune repeating elements is crucial to hearing speech in noise because it grants for superior ‘tagging’ of voice pitch, an important cue in picking out a particular voice within background noise,” stated Nina Kraus, Hugh Knowles Professor of Communication Sciences and Neurobiology and director of the Auditory Neuroscience Laboratory.
In the article “Context-dependent encoding in the human auditory brainstem relates to hearing speech-in-noise: Implications for developmental dyslexia,” Kraus and co-investigators Bharath Chandrasekaran, Jane Hornickel, Erika Skoe and Trent Nicol demonstrate that the remarkable capability of the brain to tune into relevant aspects in the soundscape is carried out by an adaptive auditory system that continuously changes its activity based on the demands of context.
Good and poor readers were asked to watch a video while the speech sound “da” was presented to them through an phone in two different sessions during which the brain’s response to these sounds was continuously measured.
In the first session, “da” was repeated over and over and over again (in what the researchers call a repetitive context). In the second, “da” was presented randomly amid other speech sounds (in what the researchers call a variable context). In an additional session, the researchers performed behavioral tests in which the kids were asked to repeat sentences that were presented to them amid increasing degrees of noise.
“Even though the children’s attention was focused on a movie, the auditory system of the good readers ‘tuned in’ to the repeatedly presented speech sound context and sharpened the sound’s encoding. In contrast, poor readers did not show an improvement in encoding with repetition,” stated Chandrasekaran, lead author of the study. “We also found that kids who had an adaptive auditory system performed superior on the behavioral tests that required them to perceive speech in noisy backgrounds.”
The study recommends that in addition to conventional reading and spelling based interventions, poor readers who have difficulties processing information in noisy backgrounds could benefit from the employment of relatively easy strategies, such as placing the child in front of the instructor or using wireless technologies to enhance the sound of a teacher’s voice for an individual student.
Interestingly, the researchers found that dyslexic kids showed enhanced brain activity in the variable condition. This might enable dyslexic kids to represent their sensory environment in a broader and arguably more creative manner, even though at the cost of the capability to exclude irrelevant signals (e.g. noise).
“The study brings us closer to understanding sensory processing in kids who experience difficulty excluding irrelevant noise. It provides an neutral index that can help in the assessment of kids with reading problems,” Kraus says.
For almost two decades, Kraus has been trying to determine why some kids with good hearing have difficulties learning to read and spell while others do not. Early in her work, because the deficits she was exploring related to the complex processes of reading and writing, Kraus studied how the cortex — the part of the brain responsible for thinking –encoded sounds. She and her colleagues now comprehend that problems associated with the encoding of sound also can occur in lower perceptual structures. Adapted from materials provided by Northwestern University, a service of AAAS. <http://www.sciencedaily.com /releases/2009/11/091111123600.htm>.
Trent Consultants News: Trent Consultants Psychology Clinic. Dedicated to the study, diagnosis, and treatment of mental, emotional and behavioral disorders. Trent Consultants has a variety of programs for parents who want to give their kids a headstart in life. Trent Consultants website www.trentconsultants.org Email: childcare@trentconsultants.org
Trent Consultants News: Trent Consultants Psychology Clinic. Dedicated to the study, diagnosis, and treatment of mental, emotional and behavioral disorders. Trent Consultants has a variety of programs for parents who want to give their kids a headstart in life. Trent Consultants website www.trentconsultants.org Email: childcare@trentconsultants.org