Generally for most Invisible Disabilities, the causes are similar in nature, faulty link in the human information processing system.
For those who have Auditory Processing Disorder (APD) it is the Auditory information processing function, which has a faulty connection. And this causes auditory processing difficulties.
APDs are normally not deaf, in fact most APDs have A1 hearing, they just do not process what they hear.
They may process part of what they hear but, without processing the rest, often the whole meaning is lost, or they perceive a totally incorrect idea of what has been said.
When APDs have a processing failure, they do not process what is being said to them.
They may be able to repeat the words back word for word, but the meaning of the message is lost, not processed.
Simply repeating the instruction is of no use if an APD is not processing, neither will increasing the volume help.
Most APDs have random Auditory Processing Disorder.
I use the word random because APDs cannot control when we process auditory information and when we do not.
(Like a loose connection in a faulty computer processor it fails when you least expect it to).
APDs have an Auditory information Processing Disorder, therefore APDs will also have problems processing verbal code, and text is only verbal code.
So Auditory Processing Disorder is extended to reading and writing, processing Auditory code.
Therefore APD is a cause of Dyslexia.
(As is the corresponding Visual Processing Disorder but for very different reasons.)
Some APDs are easily distracted by background noise and / or unexpected noises.
These Environmental factors disrupt their processing strategies, and in many instances mean that they have to go right back to the beginning of the task, to understand what they are trying to do.
Especially with a conceptual subject such as Maths.
APDs are unlikely to participate in debates unless they have had time to prepare their case.
This poses problems for self-advocacy, and can lead to discrimination and bullying.
APDs will process a discussion, as it unfolds, and may not fully understand the discussion there and then, but they may be able to fill in the gaps later.
Eventually they may have a better understanding of the topic than the actual participants, when they have finally processed the information.