Auditory Processing Disorder Study
A recent blog post ended with the mention of a peer-reviewed study showing that Fast ForWord Language v2 was an effective auditory processing disorder intervention for children with auditory processing disorders (APD). The study also provided evidence that the children’s brains rewired themselves during the eight-week study to more closely resemble typical brains. Today I want to go deeper into these findings.
How does the brain perceive speech?
To understand what brain changes the researchers found it is helpful to explain first how the brain actually goes about the task of perceiving speech. The first job the brain has to tackle when one person is listening to another person speak is to sort out the speech signal from the other sounds in the environment. That, of course, is the problem we have when listening to someone at a loud party. But that is also a challenge in most classrooms. Children, as we know, have trouble sitting perfectly still and younger children especially are often fidgeting and scooting their chairs around as well as whispering to children nearby. Add to that the noise that comes from outside the classroom - like hallway noise and playground noise - which even the best teacher cannot control, and a classroom can be a very noisy place. Part of maturation of the brain is the ability to learn to filter out irrelevant noises. But children must learn to do this and many with auditory processing disorders find that is a real challenge.
It is not clearly understood why some children develop this capacity to filter speech from noise fairly easily and others do not, but audiologists do know that the problem can be traced to specific regions of the brain, especially regions of the brainstem. These regions can be tested through a process referred to as auditory brainstem response, or ABR. This test allows researchers to measure brain stem responses to sound through use of electrodes placed on the scalp. ABR is a critical measure of sound processing because it provides information about how well the auditory pathways to the brain from the ear have matured and how well they are functioning. In the study at Auburn University, a specific kind of ABR was used that has been shown to be especially helpful in diagnosing APD in children with language-based learning problems. It is called BioMARK. Using this procedure, the researchers could objectively measure whether a specific intervention not only improved listening skills but also whether it changed the brainstem response to speech.
The research: can interventions help with auditory processing disorders?
To test whether auditory processing disorders can be improved though targeted intervention, the researchers at Auburn identified four children with APD using a battery of auditory processing, language, and intelligence tests that they administered before and after eight weeks of Fast ForWord Language v2. They also used BioMARK testing before and after Fast ForWord to determine if the actual brainstem response was affected by the intervention.
Their results were very exciting. The children who completed all of the before-treatment tests, eight weeks of Fast ForWord Language training, and all the post-treatment tests plus BioMARK showed marked improvements in their auditory processing skills. For example, the children showed improvements in a test designed to assess listening to competing words (like we have to do when two people are talking to us at the same time) as well as deciphering words that are not very clear (like listening on a cell phone when there is a poor connection). They also improved in skills like listening for sound patterns and remembering complex sentences. And, important to teachers and parents, one of the children showed marked improvement in a measure of nonverbal intelligence as well as ability to follow complex directions.
Those results alone were remarkable after just eight weeks of intervention. But the most compelling part of the research was the finding that the BioMARK results also changed significantly in the children. And the changes were positive, meaning the children’s brain stem responses resembled typical children, those who do not have any evidence of auditory processing disorders affecting language skills and listening. In other words, the eight weeks of Fast ForWord resulted in what brain scientists call “neuroplastic” changes in brain function. And the changes occurred specifically in regions that are very specific to and important for accurate listening and language processing.
Abrams, D.A., Nicol, T., Zecker, S.G., &Kraus, N. (2006). Auditory brainstem timing predicts cerebral dominance for speech sounds. Journal of Neuroscience, 26(43), 11131-11137.
King, C., Warrier, C.M., Hayes, E., &Kraus, N. (2002). Deficits in auditory brainstem encoding of speech sounds in children with learning problems. Neuroscience Letters 319, 111-115.
Krishnamurti, S., Forrester, J., Rutledge, C., & Holmes, G. (2013). A case study of the changes in the speech-evoked auditory brainstem response associated with auditory training in children with auditory processing disorders. International Journal of Pediatric Otorhinolaryngology, 77(4), 594-604. doi: 10.1016/j.ijporl.2012.12.032
Wible, B., Nicol, T., Kraus, N. (2005). Correlation between brainstem and cortical auditory processes in normal and language-impaired children. Brain, 128, 417-423.
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