Just what is the difference between language processing disorder vs. auditory processing disorder?
The answer is not simple. Even more importantly, this is a touchy subject that evokes a lot of passionate opinions amongst various professionals. This includes the obvious audiologist and speech-language pathologist as well as the less obvious educational psychologist and even some pediatricians.
Many researchers have tried to identify an easy way to separate the two with limited success. It is for this reason that a team approach is advised for diagnosing APD. It is also why many believe that only a non-language based auditory processing assessment is valid.
For the same reasons that tweaking apart language and auditory processes is not so simple, it is not simple to limit testing to non-language based tests.
Language is primarily learned through the auditory modality. It is said that 90% of learning in early childhood is “incidental learning”. This means that the child overhears the people around him and learns from them.
What is he learning?
Including, vocabulary grammar, social skills, etc.
This is an advantage lost by a child who is hearing impaired. The research clearly demonstrated the abysmal state of language development in severely hearing impaired children, who would typically cap at a 4th grade level. This data is the basis for the mandate of newborn hearing screenings. Thus, allowing us to catch hearing impairment, and more importantly provide auditory access, as soon as possible. By not waiting until a child is significantly behind their peers in language development to identify hearing impairment, we have narrowed the language gap. The earlier the child has auditory access the better. Age of intervention is a crucial component precisely because it provides the child with as much incidental learning as possible. This also provides the ability to hear and process the teachings offered in therapy sessions. Current research shows the language gap can be narrowed to a six month difference between children with hearing impairment and normal hearing children. In adulthood this is not a functionally distinguishable language difference and certainly not a language disorder. (On the other hand, auditory access management continues to be a life-long job.)
However, even Deaf children who do not avail themselves of auditory access, do learn language. They do so through non-auditory means. This indicates that language processing and auditory processing are stand-alone functions.
So, what is the problem with the differentiated diagnose of APD and LPD?
Short answer, the assessments.
Since the tests are largely language based it can be a challenge to know if poor results are due to an auditory processing disorder or a language processing disorder. But, if this is true, then how can you accept as valid any language based test until APD is ruled out? This would be equally true of language assessments as well as other educational assessments, including IQ testing. And yet, sadly, all too often children go for treatment for years for a language disorder, or worse are dismissed as being of too low intelligence, just because the potential contribution of an auditory disorder is overlooked as.
This situation is further complicated by the fact that auditory processing, unlike hearing acuity, is not a singular function. Some of these functions can be assessed using non-language based test items, but not all.
Did you know that phonemic awareness is actually an auditory skill?
No letter recognition is needed.
No knowledge of the sound symbol association is necessary.
No visual cues are provided when assessing phonemic awareness.
Understanding this fact makes all the difference in how we approach assessing a child who is struggling to learn the language skill of reading. Effectively assessing means effectively treating. See some treatment considerations here.