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.
Apperceptive agnosia
Following Hermann Munk's identification of a condition he called "Seelenblindheit" (mind-blindness) Heinrich Lissauer published an exhaustive diagnostic evaluation of a patient who could not, or only with great difficulty, visually identify common objects. Because primary visual processing was intact, Lissauer considered the possible diagnostic distinction between deficits in perception (apperceptive agnosia) and in recognition (associative agnosia).