Download PSY 342: Review for Exam 3 Chapter 11: Sound and the Auditory

PSY 342: Review for Exam 3
Chapter 11: Sound and the Auditory System
Sound wave created by air molecules (condensation and rarefication)
Pure tone creates a sine wave (amplitude=loudness; frequency=pitch)
Loudness measured in Decibels; frequency in Hertz
Complex tone created by fundamental frequency and harmonics
Human hearing range is 20-20,000 Hertz
Ear structures (outer, middle and inner ear)
Outer ear: pinna and auditory canal (protects tympanic membrane or ear drum)
Middle ear: tympanic membrane and three ossicles (malleus, incus, stapes) amplify vibrations
Inner ear: Cochlea which contains the Organ of Corti
Organ of Corti: Basilar membrane and tectorial membrane move in response to vibration.
Hair cells vibrate and release neurotransmitter to create action potentials in auditory nerve
(transduction: hair cell movements become neural signals)
Bekesy developed place theory of hearing from studies of cadavers
Place theory: sound frequency creates response in different places on basilar membrane
High frequencies at base of membrane; low frequencies at apex
Complex tone creates response at fundamentals and harmonics.
Hearing loss: conductive (outer and middle ear) and sensorineural (inner ear)
Presbycusis: age related hearing loss, mostly high freqs, more in men
Noise-induced hearing loss: loud sounds from guns, music, machines, etc)
Path to auditory cortex: inferior colliculus> medial geniculate (thalamus)> A1 on cortex
A1 then sends to other parts of cortex; ventral stream (what) and dorsal stream (where)
Cochlear implants directly stimulate auditory nerve (opposed by some members of deaf community)
Chapter 12: Sound Localization and Auditory Scene
Sounds are all around us; need to be localized by azimuth (L-R), distance and elevation (up-down)
Sounds directly in front of you are easier to locate than sounds to side or behind
Use binaural (two ears) cues: interaural time difference (ITD) and acoustic shadow created by head
Acoustic shadow works more on high freqs; less on low freqs
Acoustic scene analysis: which sounds from which sources.
Heuristics (Gestalt strategies): Onset time, location, similarity of timbre and pitch
Auditory stream segregation: link sounds by pitch: high with high; low with low
Other Gestalt rules for grouping sounds: Proximity in time, auditory continuity, past experience
Interaction between vision and sound: visual capture or ventriloquist effect
Ex: moving balls “collide” only when we add sound
Chapter 13 Speech Perception
Humans still beat computers when it comes to producing and understanding speech
Vocal tract: Nasal and oral cavities, vocal cords, and articulators (tongue, lips, teeth)
Peaks of air pressure changes create formants. Each vowel has pattern of formants.
Consonants produced by constriction in vocal tract by articulators (teeth, lips, etc)
Phoneme: smallest unit of speech that changes the meaning of a word.
English has 13 vowel sounds, 24 consonant sounds and 47 phonemes
Variability: speakers differ in pitch, accent, speed of speaking, pronunciation.
We still perceive most variability by using perceptual constancy
McGurk effect: speech perception can be influenced by vision (reading lips)
Link between seeing faces and perceiving speech (FFA on cortex)
Phonemic restoration effect: fill in phoneme covered by cough
Segmentation problem: no physical break in acoustic signal during hearing speech
Use top-down processing (knowledge of language) to help us determine meaning
Also use characteristic of speaker: age, gender, emotional state, seriousness
Two main brain areas for language: Broca’s area in frontal lobe, Wernicke’s area in temporal lobe
Broca’s area> production (articulation) of speech. Located next to motor strip.
Wernicke’s area> comprehension of spoken word. Located next to A1
Aphasia: loss of language skills. Most often created by damage to left hemisphere
Broca’s aphasia: problems in producing speech. Difficulty in forming speech sounds.
Wernicke’s aphasia: problems in comprehending spoken language. Speech lacks meaning.
Brain plasticity in learning phonemes before age one
Music and the cortex: comprehended best by right hemisphere before music education
With music education> music as a language starts to shift to left hemisphere.