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PART 3 Integration and Control Systems

decreased ability to localize the origin of certain sounds. In somepeople, this leads to a general sense of disorientation. In addition,CNS defects in the auditory pathways can result in difficultyunderstanding sounds with echoes or background noise. Such adeficit makes it difficult for elderly people to understand rapid orbroken speech.With age, the number of hair cells in the saccule, utricle, andampullae decreases. The number of otoliths also declines. As a

result, elderly people experience decreased sensitivity to gravity,acceleration, and rotation, leading to dizziness (instability) and ver-tigo (a feeling of spinning). Many elderly people feel they cannotmaintain posture and are prone to fall.

ASSESS YOUR PROGRESS

49. Explain the changes in smell, taste, vision, hearing, andbalance that occur with aging.