Client’s comprehensive hearing and visual test results supports what I have found through a review of research. Dyslexia affects the auditory and visual processing systems in the brain. Clients experienced either sound intolerance to loud sounds (video) or sound sensitivity to speech (video) creating behavioral characteristics of auditory fatigue with visual processing difficulties.
Brain plasticity research shows individuals benefit from intervention; the brain can change as long as there is brain health. (More videos being developed in 2019, on brain plasticity and dyslexia.)
According to a national survey conducted by the Center for Disease Control and Prevention (CDC) (2013), 4.9 million children in the U.S., ages 3-17, have a learning disability. The most common learning disability is dyslexia, which is estimated to affect five to ten percent of children attending school (Handler, Fierson, 2011; Cardon, et al., 1994). Dyslexia is not outgrown (Ahissar, Protopapas, Reid & Merzenich, 2000).
VISION:
Kaplan who is recognized as a “pioneer” in the field of vision therapy and learning disabilities found mild visual processing deficits (VPD) in children who have difficulties in the areas of reading and motor coordination, often associated with learning disabilities and attention deficit disorder.
In a study completed by Grisham (1986), 50 percent or more of children with reading disabilities experienced difficulties with Visual Processing Dysfunctions (VPD) when compared to students without reading difficulties; the VPD most often found were difficulties using both eyes together to look at a target, keeping the object/letter clear and single, and accommodation (ability to focus quickly on objects of various depth perception distances).
AUDITORY:
Blau, et. al. (2009) found decreased neural activity in the brain’s hetermodal superior temporal sulcus and gyrus when presented with “congruent sounds” (recognized sound-letter combinations) and “incongruent sounds (non-recognized sound-letter combinations).
Magnetoencephalographic imaging (MRI) of the auditory cortex provided evidence that struggling readers suffer from auditory processing deficits during “brief and rapidly successive inputs” of speech, (receptive speech) causing unclear phonetic pronunciation (Nagarajan, Mahncke, Salz, Tallal, Roberts & Merzenich, 1999).
AUDITORY AND VISUAL:
Think about the numerous everyday tasks associated with matching sounds with a visual stimulus creating learned responses to stimulus:
(1) Remembering what sound is associated with an animal, an environmental sounds, a phonemic sound
(2) Recognizing a person’s voice
(3) Listening skills require lip movement to synch up with speech; for sounds to be heard clearly in the order spoken
(4) Learning academic skills like reading, spelling, creative writing
(5) Learning and remembering to complete a sequencing task (following directions, cooking, getting ready for …)
(6) Motor responses based on what is seen and heard
(7) Remembering how to say a word, expressive speech
A dysfunction in either the auditory processing system and/or the visual processing system has the potential to negatively affect the brain’s ability to develop a strong integrated auditory-visual response (“audiovisual speech”).
Researchers Blau V., Atteveldt, N., Ekkebus, M., Goebel, R., Blomert, L. (2009) assessed auditory processing and visual processing skills using MRI scans in participants diagnosed with dyslexia, comparing them to a norm group, and found deficits in both the auditory processing system and visual processing system.
MRI studies show that the brain’s superior temporal sulcus must integrate auditory input (sounds) with a distinct visual input (letters) to learn speech and reading skills (McNorgan, Booth, 2015; Chen, Spence, 2011; Beauchamp, M.S., Lee, K.E., Argall, B.D., & Martin, A., 2004; Bernstein, L. E., Jr., Wagner, M., & Ponton, C.W., 2008).
Van Atteveldt, N., Formisano, E., Goebel, R., Blomert, L. (2004) found through MRI scans that reading and spelling activate parts of the brain associated with integrating auditory and visual processing skills; these are the brain’s heteromodal superior temporal sulcus and gyrus cortex; the auditory cortex’s heschl sulcus; and the planum temporal cortex.
McNorgan and Booth during an MRI study found that learning to read results in a stronger integrated auditory-visual processing system, specifically in the “ventral visual-object processing stream.”