Speech perception
Agnosia is "the loss or diminution of the ability to recognize familiar objects or stimuli usually as a result of brain damage". There are several different kinds of agnosia that affect every one of our senses, but the two most common related to speech are speech agnosia and phonagnosia.
Obstructive sleep apnea
The hypoxia (absence of oxygen supply) related to OSA may cause changes in the neurons of the hippocampus and the right frontal cortex. Research using neuro-imaging revealed evidence of hippocampal atrophy in people suffering from OSA. They found that OSA can cause problems in mentally manipulating non-verbal information, in executive functions and working memory. This repeated brain hypoxia is also considered to be a cause of Alzheimer's disease.