chapter 9 hearing and perception

Sensation

Transformation of environmental energy into neural signals.

Perception

Brain’s interpretation of sensory information.

Transduction

Conversion of physical stimulus to electrical neural activity.

Amplitude

Height of sound waves; determines loudness.

Timbre

Complexity of sound; tone quality.

Pinna

Outer ear structure that collects sound.

Ossicles

Middle ear bones (malleus, incus, stapes) that amplify vibrations.

Cochlea

Fluid-filled inner ear structure for sound transduction.

Hair cells

Sensory cells in basilar membrane that convert sound vibrations to neural signals.

Place theory

Different pitches activate different locations on basilar membrane.

Frequency theory

Pitch determined by rate of auditory nerve firing.

Auditory pathway

Cochlea → CN8 → cochlear nucleus → inferior colliculus → MGN (thalamus) → auditory cortex.

Lateralization

Localization of language mainly in the left hemisphere.

Broca’s aphasia

Non-fluent, effortful speech, poor grammar, good comprehension.

Wernicke’s aphasia

Fluent but meaningless speech, poor comprehension.

Word deafness

Inability to recognize spoken words; auditory verbal agnosia.

Anomia

Difficulty naming or finding words.

Pure alexia

Word blindness; inability to read with intact writing/speech.

Surface dyslexia

Impaired whole-word reading; relies on phonetic reading.

Phonological dyslexia

Impaired phonetic reading; can read familiar whole words.

Agraphia

Total inability to write.

Dysgraphia

Impaired writing ability.

Developmental dyslexia

Reading disorder involving letter reversals, poor phonological processing.

Magnocellular deficit theory

Dyslexia linked to impaired visual motion processing pathways.