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Introduction: Hold the Phone

PART I  Hearing and Balance

Pressure Waves in the Air Are Perceived as Sound

BOX 6.1: The Basics of Sound

The external ear captures, focuses, and filters sound

The middle ear concentrates sound energies

The cochlea converts vibrational energy into neural activity

RESEARCHERS AT WORK: Georg von Békésy and the cochlear wave

The hair cells transduce movements of the basilar membrane into electrical signals

Auditory Signals Run from Cochlea to Cortex

Our Sense of Pitch Relies on Two Signals from the Cochlea

Brainstem Systems Compare the Ears to Localize Sounds

The Auditory Cortex Processes Complex Sound

Hearing Loss Is a Widespread Problem

SIGNS & SYMPTOMS: Restoring Auditory Stimulation in Deafness

The Inner Ear Provides Our Sense of Balance

Some Forms of Vestibular Excitation Produce Motion Sickness

PART II  The Chemical Senses: Taste and Smell

Chemicals in Our Food Are Perceived as Five Basic Tastes

Tastes excite specialized receptor cells on the tongue

The five basic tastes are signaled by specific sensors on taste cells

Taste information is transmitted to several parts of the brain

Chemicals in the Air Elicit Odor Sensations

The sense of smell starts with receptor neurons in the nose

Olfactory information projects from the olfactory bulbs to several brain regions

Many vertebrates possess a vomeronasal system