Agnosia
Agnosia is the inability to process sensory information. Often there is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss. It is usually associated with brain injury or neurological illness, particularly after damage to the occipitotemporal border, which is part of the ventral stream. Agnosia only affects a single modality, such as vision or hearing. More recently, a top-down interruption is considered to cause the disturbance of handling perceptual information.
Auditory agnosia
The term auditory agnosia was originally coined by Freud (1891) to describe patients with selective impairment of environmental sounds. In a review of the auditory agnosia literature, Ulrich re-named this disorder as non-verbal auditory agnosia (although sound auditory agnosia and environmental sound auditory agnosia are also commonly used). This disorder is very rare and only 18 cases have been documented. In contradiction to pure word deafness and general auditory agnosia, this disorder is likely under-diagnosed because patients are often not aware of their disorder, and thus don’t seek medical intervention.