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Amblyaudia
Amblyaudia (amblyos- blunt; audia-hearing) is a brain based hearing disorder that results from auditory deprivation during critical periods of brain development. Individuals with amblyaudia have normal hearing sensitivity (in other words they hear soft sounds) but have difficulty hearing in noisy environments like restaurants or classrooms. Amblyaudia can be conceptualized as the auditory analog of the better known central visual disorder amblyopia. The term “lazy ear” has been used to describe amblyaudia although it is currently not known whether it stems from deficits in the auditory periphery (middle ear or cochlea) or from other parts of the auditory system in the brain, or both. A characteristic of amblyaudia is suppression of activity in the non-dominant auditory pathway by activity in the dominant pathway which may be genetically determined and which could also be exacerbated by conditions throughout early development.
==Physiology==
Amblyaudia is a developmental disorder related to brain organization and function rather than what is typically considered a “hearing loss” (damage to the cochlea). When animals are temporarily deprived of hearing from an early age, profound changes occur in the brain. Specifically, cell sizes in brainstem nuclei are reduced, the configuration of brainstem dendrites are altered and neurons respond in different ways to sounds presented to both the deprived and non-deprived ears (in cases of asymmetric deprivation). This last point is particularly important for listening tasks that require inputs from two ears to perform well. There are multiple auditory functions that rely on the computation of well calibrated inputs from the two ears. Chief among these is the ability to localize sound sources and separate what we want to hear from a background of noise. In the brainstem, the auditory system compares the timing and levels of sounds between the two ears to encode the location of sound sources (sounds that originate from our right as opposed to left side are louder and arrive earlier in our right ear). This ability to separate sound sources not only helps us locate the trajectories of moving objects, but also to separate different sound sources in noisy environments.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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