One very common comment I hear from parents I work with is that their child doesn't seem to "hear" them and/or the teacher complains that they aren't paying attention. Oftentimes, parents wonder if this is ADHD and, more often than not, the child was referred for hearing testing when they were younger. Usually, the hearing testing is normal and so that is dismissed as a reason why the child isn't "listening" or paying attention.
When you get a hearing test done, what is being tested is the actual hearing mechanism which "includes the outer ear—where sound waves are collected, the middle ear—where sound is converted to mechanical energy, and the inner ear—containing the cochlea" (Riggs, n.d). Hearing tests assess the integrity of the cochlea and other parts of the ear involved in converting those sound waves.
After those sound waves are collected and converted, they have to be sent on to other parts of the brain to be processed-first to the brainstem, then up to the thalamus, and then over to the temporal lobe. What happens between the ear and along that auditory nerve is called auditory processing. Auditory processing is how our brain sends those signals and makes sense of them.
A child or adult can have absolutely perfect hearing and have very impacted auditory processing. Many of the children I work with have been diagnosed with an auditory processing disorder. Children with APD or auditory processing challenges may have difficulty with learning to read, suffer from inattention, mishear words or sentences, have poor peer interactions due to missing social cues, difficulty working in a noisy environment, and language delays. Here is a great checklist for APD symptoms: https://kidshear.com.au/wp-content/uploads/2011/11/CAPD-Check-List.pd
Auditory processing has many components, including:
Auditory attention- can I pay attention to what is being heard
Auditory discrimination—can I distinguish between different sounds or words, such as the three phonemes in the word bat- /b/ /a/ /t/
Auditory sequential processing—this refers to how many pieces of information I can listen to, hold on to, recall, and use.
Auditory memory—can I hold on to auditory information long enough to use it
Auditory figure-ground—can I attend to the auditory information I need to but block out background noise, such as listening to the teacher speaking while blocking out the ticking clock, the pencil tapping, and the door opening
Temporal processing—this is how sounds are processed in the temporal lobe and the brain's ability to "hear" the difference between words in a sentence, syllables, and individual sounds in a word. This is deeply impacted by poor timing in the thalamus.
When an infant is born, they have very selective hearing and are very sensitive to sounds. They are attuned to their mother's voice and her heartbeat. Any unexpected sound will initiate a startle response as the brain perceives that as unknown and thus threatening. As babies move through their reflex patterns and thus their developmental milestones, their auditory system matures and eventually develops a more mature pathway called the non-classical pathway. If this newer pathway is not developed, children will remain overly sensitive to sounds, and it may elicit emotional and behavioral symptoms, including covering the ears, crying, emotional outbursts, hiding, isolation, and more.
To address challenges with auditory processing, you can have their primitive reflex patterns (these are what enable children to meet their developmental milestones) evaluated to ensure they have all been integrated. Once those are integrated, some training for the midbrain can help speed things up with programs like Interactive Metronome. From there, an evaluation from a qualified audiologist who specializes in APD can identify areas in which specific auditory training can be done to improve outcomes and functioning.
References
CAPD Checklist. Kids Hear Diagnostic Audiology. https://kidshear.com.au/wp-content/uploads/2011/11/CAPD-Check-List.pdf
Riggs, L. Auditory processing: what is it? NACD Journal. https://www.nacd.org/auditory-processing-what-is-it-hearing-vs-processing/