Chapter 10 Flashcards
sound waves
undulating displacement of molecules caused by changing pressure
frequency
number of cycles that a wave completes in a given amount of time
hertz (Hz)
measure of frequency (repetition rate) of a sound wave; 1 hertz is equal to 1 cycle per second
3 physical attributes of sound waves
frequency, amplitude, complexity—>produced by the displacement of air molecules
how fast do sound waves travel?
fixed speed of 1100 feet per second
Frequency & pitch perception
the rate at which sound waves vibrate is measured as cycles per second, or hertz
amplitude and perception of loudness
intensity of sound is usually measured in decibels
complexity and timbre
mixture of frequencies; a sound’s complexity determines its timbre
timbre
perception of sound quality; perceived characteristics that distinguish a particular sound from all others of similar pitch and loudness
low pitch sounds
have slow wave frequencies (fewer cycles per second)
high pitched sounds
have faster wave frequencies (many cycles per second)
range of human’s hearing
20-20,000 hertz
perfect (absolute) pitch
runs in families; suggests genetic influence
amplitude
intensity of a stimulus; in audition, roughly equivalent to loudness, graphed by increasing height of a sound wave
decibel (dB)
unit for measuring the relative physical intensity of sounds
what causes increased loudness?
increase compression of air molecules intensifies the energy in a sound wave, which amps the sound—makes it louder
pure tones
sounds with a single frequency
complex tones
sounds that mix wave frequencies together in combinations
fundamental frequency
the rate at which the complete waveform pattern repeats
overtones
set of higher-frequency sound waves that vibrate at whole-number (integer) multiples of the fundamental frequency
noise
sounds that are aperiodic or random
frequency of waves
pitch
height (amplitude) of waves
loudness
left temporal lobe
speech
right temporal lobe
music
what does music help us do?
regulate our own emotion and to affect the emotion of others
buzz
nonspeech and nonmusic noise produced at a rate of about 5 segments per second
segment
a distinct unit of sound
normal speed of speech
8-10 segments per second; capable of understanding speech at the rate of 30 segments per second
categorization of sounds
auditory system must have a mechanism for categorizing sounds as being the same despite small differences in pronunciation. Experience must affect this mechanism bc different languages categorize speech differently
loudness
magnitude of a sound as judged by a person
pitch
the position of each tone on a musical scale as judged by the listener
prosody
melodical tone of the spoken voice
progression of sound waves
ear collects waves–> converts to mechanical energy–> electrochemical neural energy–> brainstem (auditory cortex)
pinna
funnel-like external structure of the outer ear catches waves and deflects them to the external ear canal
external ear canal
short distance from pinna inside the head; amplifies sound waves somewhat and directs them to the eardrum at its inner end
middle ear
air filled chamber that containes the ossicles
ossicles
bones of the middle ear; malleus (hammer), incus (anvil), and stapes (stirrup); attach the eardrum to the oval window
oval window
an opening in the bony casing of the cochlea
cochlea
inner-ear structure that contains the auditory receptor cells
organ of Corti
receptor cells in the cochlea and the cells that support them
basilar membrane
receptor surface in the cochlea that transduces sound waves into neural activity
hair cell
sensory neurons in the cochlea tipped by cilia; when stimulated by waves in the cochlear fluid, outer hair cells generate graded potentials in inner hair cells, which act as the auditory receptor cells
cilia
filaments at the tip of a hair cell
tectorial membrane
cilia in the basilar membrane loosely contact this membrane
processing sound waves
pressure from the stirrup on the oval window makes conchlear fluid move; the waves traveling through the fluid bend the basilar and tectorial membranes which stimulates the cilia of the outer hair cells. This stimulation generates graded potentials in the inner hair cells that act as auditory receptor cells.
What determines how much neurotransmitter is released?
the change in membrane potential of the inner hair cells varies the amount of neurotransmitter released
Fast wave frequencies
caused maximum peaks of displacement near the base of the basilar membrane
slower wave frequencies
cause maximum displacement peaks near the membrane’s apex
what do hair cells do?
transform sound waves into neural activity
how many sets of hair cells do we have?
two: 500 inner, 12000 outer
Are both inner and outer hair cells auditory receptors?
NO. only inner
How are inner hair cells stimulated?
the movement of the basilar and tectorial membranes causes the cochlear fluid to flow past the cilia of the inner cells, bending them back and forth
Purpose of outer hair cells?
to sharpen the cochlea’s resolving power by contracting or relaxing
how to outer hair cells contract or relax?
axons in the auditory nerve–>outer hair cells send a message to the brainstem auditory areas and receives a message back that causes the cells to alter tension
depolarization
movement of cilia toward the tallest
hyperpolarization
movement toward the shortest cilia
what do inner hair cells synapse with?
neighboring bipolar cells, the axons that form the auditory (cochlear) nerve
auditory nerve
forms part of the eighth cranial nerve, the auditory vestibular nerve that governs hearing and balance
how many inputs to bipolar cells receive?
ONE. from a single inner hair cell recetpor
do projections from the cochlear nucleus connect with cells on the same side of the head?
They connect with cells on the same and opposite sides of the head–> perceptions of a single sound
Pathways from the interior colliculus
ventral region–> primary auditory cortex; dorsal region–> projects to the auditory cortical regions adjacent to area A1
medial geniculate nucleus
major thalamic region concerned with audition
primary auditory cortex (area A1)
asymmetrical structures, found within Heschl’s gyrus in the temporal lobes, that receive input from the ventral region of the medial geniculate nucleus
where is A1 located?
within Heschl’s gyrus, surrounded by secondary cortical areas A2
Wernicke’s area
secondary auditory cortex (planum temporale) lying behind Heschl’s gyrus at the rear of the left temporal lobe that regulates language comprehension; also called posterior speech zones
lateralization
process whereby functions become localized primarily on one side of the brain
insula
located within the lateral fissure, multifunctional cortical tissue that contains regions related to language, to the perception of taste, and to the neural structures underlying social cognition
is the auditory cortex symmetrical?
no–it is anatomically and functionally asymmetrical
Lateralized functions
left–> Language; right–> music
tonotropic representation
property of audition in which sound waves are processed in a systematic fashion from lower to higher frequencies
cochlear implant
electronic device implanted surgically into the inner ear to transduce sound waves into neural activity and allow a deaf person to hear
Pitch and tonotropic representation
hair-cell cilia at the base of the cochlea are maximally displaced by high-frequency waves that we hear as low-pitched sounds.
pitch and bipolar cells
convey information about the spot on the basilar membrane from apex to base that is being stimulated
Detecting loudness
simplest way for a cochlear (bipolar) cells to indicate sound-wave intensity is to fire at a higher rate when amplitude is greater
Detecting location
since each cochlear nerve synapses on both sides of the brain–> mechanisms for locating the source of a sound
left-ear, right-ear arrival times
detecting location; carried out in the medial part of the superior olivary complex
What happens when we don’t detect a different between the left and right ears?
we infer that the sound is directly in front of or behind us
How do we detect the source of a sound?
relative loudness and location (ear)
Neurons in ventral pathway
decode spectrally complex sounds (object recognition–including the meaning of speech sounds)
neurons in the dorsal pathway
less is known; plays a role in integrating auditory and somatosensory information to control speech production
Is language genetically determined?
it is genetically based in humans
Syntax
rules that specify exactly how various parts of speech are positioned in a sentence
creolization
development of a new language from what was formerly a rudimentary language or pidgin
Broca’s area
anterior speech area in the left hemisphere that functions with the motor cortex to produce the movements needed for speaking
Broca’s area (shorter definition)
stores motor programs for speaking words
Wernicke’s area (shorter definition)
contains sound images of words
Aphasia
inability to speak or comprehend language despite the presence of normal comprehension and intact vocal mechanisms.
Wernicke’s aphasia
is the inability to understand or to produce meaningful language even though the production of words is still intact
Broca’s aphasia
is the inability to speak fluently despite the presence of normal comprehension and intact vocal mechanisms.
Arcuate fasciculus
messages travel to Brocas from Wernicke’s through this; connects these two regions
stimulation to A1
produces simple tones–ringing sounds; analyzes bursts of noise; analyzes incoming auditory signals, speech and nonspeech
stimulation to adjacent areas to A1 (Wernicke’s)
causes interpretation of sound (ex. buzzing is bc of cricket); analyzes complex auditory stimulation; responsible for higher-order signal processing required for analyzing language sound patterns
four important cortical regions for language
broca’s, wenicke’s, dorsal area of the frontal lobes and the areas of the motor and somatosensory cortex (control facial, tongue, throat muscles)
supplementary speech area
speech-production region on the dorsal surface of the left frontal lobe
speech arrest
stopping of ongoing speech completely
aneruysm
bulge in a blood-vessel wall caused by weakening of the tissue
amusia
tone deafness–inability to distinguish between musical notes
Stroke & Music
activates the motor and premotor cortex and can improve gait and arm training after stroke
Aphasia & Music
enhances the ability to discriminate speech sounds and to distinguish speech from background noise
Parkinson’s & music
stepping to the beat of music can improve their gait length and walking speed
echolocation
ability to identify and locate an object by bouncing sound waves off the object
