Auditory Perception

Auditory perceptual tasks involving the discrimination of fine differences in frequency, duration, or rhythmic pattern were given to a group of sixth form schoolboys. The results indicate that there is a wide range of auditory skills for different individuals, even within a relatively homogeneous group. There are also differences in a person''s ability to carry out distinct tasks; there does not necessarily appear to be any correlation between his ability for each task.The findings support observations arising out of consideration of hearing problems in children and adults that pure tone threshold audiometry and its derivatives give an inadequate definition of hearing disorder and a limited understanding of the nature of hearing.     

Auditory agnosia

Auditory agnosia can be defined as the defective recognition of non-verbal sounds and noises. The clinical picture of this disorder is described and the scarcity of knowledge of auditory agnosia derived purely from single cases is discussed. Next, experimental studies on unselected series of brain-damaged patients, especially designed to clarify the relation of auditory agnosia to aphasia and to the hemispheric locus of the lesion are reported. The results consistently point to the existence of two types of auditory agnosia, a semantic-associative one, specifically associated with lesions of the left hemisphere and aphasia, and a discriminative one, specifically associated with lesions of the right hemisphere. The hypothesis is advanced that the semantic-associative variety of auditory agnosia is part of a wider cognitive disorder.     

Auditory processing in birds

Over the past year, much progress has been achieved in the study of both the peripheral and the central auditory systems of birds. Significant advances have been made in the study of hair cells, including elucidation of the mechanisms of selectivity for sound frequency, functional differentiation, efferent innervation, and regeneration. Most of the studies of central auditory neurones have concerned the developmental and physiological correlates of vocal learning in songbirds and sound localisation in owls.     

Auditory processing in anurans.

Anurans (frogs and toads) represent an example of peripheral specialization of the auditory systems. Their inner ear contains two distinct auditory organs: the amphibian papilla and the basilar papilla. Each organ is tuned to different species-specific frequency ranges. Because of this peripheral specialization, anurans offer an excellent opportunity to explore neural decoding of complex sounds in the central auditory system.