APD, Dyslexia, or Both?

APD Dylexia or BothAccording to the National Institutes of Health, in children referred for learning difficulties, around 43% have Auditory Processing Disorder (APD).  In addition, 25% of all children tested for learning disabilities were found to have coexisting APD and dyslexia. Dyslexia and Auditory Processing Disorder share many of the same symptoms, but they are different disorders. Dyslexia is a language-based learning disability often associated with slow or inaccurate reading, poor spelling, poor writing, or mixing up similar words. Auditory Processing Disorder is an abnormality in the processing of sound in the central auditory nervous system.  This affects the brain’s ability to filter and process sounds and words. Research indicates that 50% to 70% of children with dyslexia have an underlying disorder within the auditory system that has disrupted the normal acquisition of language.

Overlooking an auditory processing disorder can lead to years and years of extra reading instruction working around an underlying problem. While many symptoms of dyslexia overlap with auditory processing disorders, children with APD have difficulty with spelling and learning to read due to their inability to hear clearly. Phonological awareness skills (recognizing the sound units that make up words) are often poor in children with Auditory Processing Disorder stemming from the auditory related neurological disorder. Research in brain imaging studies and auditory evoked potentials (brain wave responses to sound) has documented that impairments in the neural encoding of acoustic elements crucial for differentiating consonants (such as subtle pitch and timing differences in speech sounds) contribute the poor consonant differentiation and phonological skills seen in children with reading impairments.  Since Auditory Processing Disorder affects the ability to distinguish similar-sounding sounds, this in turn, affects a child’s ability to learn how letters represent those sounds. For example, when the teacher says “bat”, sometimes they hear “bat” but sometimes they may they hear “dat,” “bap,” “gat,” “vat,” “back,” or “pat.” So when asked to spell “bat” they may write “dat.” Since they often confuse what letters sound like, children with APD have trouble associating a specific sound with a specific letter (i.e. b = “buh” not “duh”) because they hear that letter pronounced differently every time.  Phonological awareness activities such as manipulating sounds in words will also be difficult. For example, when asked to say “me” and then say the word again changing the “mmm” sound to “nnn” they may have trouble because they don’t consistently hear the difference in these sounds.

It is important to consider how much success in school relies upon receiving an intact auditory message.  Auditory processing evaluations focus on looking for an underlying auditory related learning disability so that the child can receive treatment to help them reach their full potential.  Dyslexia evaluations typically include intellectual and academic achievement testing.  Sometimes receptive (listening) and expressive language skills may be assessed as part of a dyslexia evaluation as well.  However, a dyslexia evaluation does not test children for auditory processing disorder. To rule out auditory processing disorder, a child must be evaluated by an audiologist specializing in assessment of the central auditory nervous system.

  • Up to 43% of Children with Learning Difficulties Have Auditory Processing Disorder (APD)
  • 25% of Children with Learning Difficulties Have APD and Dyslexia
  • Auditory Processing Center, LLC
    541 Highway 80 West
    Suite C
    Clinton, MS 39056
    Phone: (601) 488-4189
    Fax: (601) 488-4888