Scriptural statements sometimes deny disbelievers the ability to hear. In this theological discussion, such language is not read as an absolute denial of physical ears, since they could hear ordinary sounds.
It is explained instead with reference to the reception of truth and the particular capacity or enablement connected with accepting and acting upon it. A person may possess a functioning organ of hearing without the acceptance of truth actually taking place.
This helps distinguish ability understood as the availability of instruments from ability understood in relation to the occurrence of a particular action.