Children and adults diagnosed with learning disorders show highly variable perceptual and cognitive profiles. Many factors can contribute to the diagnosis of learning problems including basic perceptual physiology. BioMARK (Biological Marker of Auditory Processing) is a neurophysiological test used to quickly and objectively identify disordered processing of sound – the auditory brainstem response (ABR) to speech – which has been associated with learning impairments in many children.
Until now, auditory processing evaluations have consisted of behavioural measures which are subjective in nature, and may in some cases be confounded by client variables such as attention, memory, motivation, or simply a failure to understand the task at hand. As a supplementary diagnostic tool, BioMARK provides a measure that is objective and non-invasive, and directly assesses the neural processing of sound.
A BioMARK test is particularly important for individuals with speech and language disorders (reading, auditory, autism, dyslexia). Brainstem measures are related to the encoding of linguistic information and can provide a biological marker for auditory function in children with language-based learning problems. Of the 5% to 10% of children diagnosed with learning disabilities, approximately 30% can be explained by subtle auditory deficits of neural processing that contribute to delayed and abnormal reading skills. If this is the case, an abnormal BioMARK response will appear on the test, and the origin of the learning difficulty identified. Clients with neural processing difficulties are also those who will benefit the most from Auditory Training Programs, so BioMARK also acts as a screening tool for therapy recommendations.
Anyone can undertake a BioMark test providing they can remain awake and quiet for 20-30 minutes while watching a movie, for example, since the test requires no active participation from the client. Electrodes are placed on the head and an earphone in the right ear for delivery of the acoustic stimulus. A ‘Click’ evoked ABR is performed first to confirm normal standard ABR, then results from the BioMARK test using a ‘Da’ sound are compared to an age appropriate normative database to assess the latency, slope and spectral amplitude, and produce a BioMARK score.