AuditionAuditionFrequency and AmplitudeFrequency and Amplitude AuditionAudition

the sense of hearingthe sense of hearing FrequencyFrequency

the number of complete wavelengths that the number of complete wavelengths that pass a point in a given time pass a point in a given time = pitch= pitch

Pitch (wave frequency, Hz)Pitch (wave frequency, Hz) High frequency = high pitch High frequency = high pitch low frequency = low pitchlow frequency = low pitch

AmplitudeAmplitude

Amplitude:Amplitude: height of sound wave = loudness of height of sound wave = loudness of soundsound

Timbre: quality, complexity of soundTimbre: quality, complexity of sound

Average human: hears tones from 20Hz to Average human: hears tones from 20Hz to 20,000Hz.20,000Hz.

Women tend to hear higher frequencies Women tend to hear higher frequencies Theory: men = Louder activities more often…Theory: men = Louder activities more often…

The Intensity of Some The Intensity of Some Common SoundsCommon Sounds

From Waves to SoundFrom Waves to Sound Outer EarOuter Ear

Channels sound wave through Channels sound wave through auditory canal to auditory canal to eardrum eardrum

Middle EarMiddle Ear Eardrum:Eardrum: Membrane/ converts wave to vibrations Membrane/ converts wave to vibrations Vibrations pass through piston (Vibrations pass through piston (hammer, anvil, hammer, anvil,

stirrup:stirrup: smallest bones in human body!) piston smallest bones in human body!) piston concentrates vibrations of the eardrum on the concentrates vibrations of the eardrum on the cochlea’s oval windowcochlea’s oval window

Inner EarInner Ear CochleaCochlea: converts vibrations into neural activity : converts vibrations into neural activity

(vibration = ripples in basilar membrane fluid(vibration = ripples in basilar membrane fluid Bending hair cells = auditory neural impulseBending hair cells = auditory neural impulse

In other wordsIn other words……

From sound waves to vibrations to fluid From sound waves to vibrations to fluid waves to neural impulse to auditory cortex waves to neural impulse to auditory cortex (temporal lobe) = hearing!(temporal lobe) = hearing!

Hair Cells: Basilar MembraneHair Cells: Basilar Membrane

How do we discern pitch?How do we discern pitch?

Place TheoryPlace Theory Specific places along the basilar membrane Specific places along the basilar membrane

match a tone with a particular pitchmatch a tone with a particular pitch

Frequency TheoryFrequency Theory rate of sound wave = rate of neural rate of sound wave = rate of neural

impulses to the brain (# of neural impulses impulses to the brain (# of neural impulses determines pitch) ex. 100 sound determines pitch) ex. 100 sound waves/second = 100 neural impulses = waves/second = 100 neural impulses = pitch)pitch)

How We Locate SoundsHow We Locate Sounds Brain analyzes differences in what is Brain analyzes differences in what is

heard by each ear to determine where heard by each ear to determine where sound is coming from… (3 dimensional)sound is coming from… (3 dimensional)

Hearing LossHearing Loss

1.1. Most common physical disabilityMost common physical disability

2.2. 35 million Americans (500 million worldwide)35 million Americans (500 million worldwide)

3.3. Recent study: 60% of American college Recent study: 60% of American college students suffer from high frequency hearing students suffer from high frequency hearing loss.loss.

4.4. Each 5 db increase, time it takes for Each 5 db increase, time it takes for permanent damage cut in half (after 85)permanent damage cut in half (after 85)

5.5. Men: greater degree of hearing loss at every Men: greater degree of hearing loss at every age (loud music or changes in cochlea that age (loud music or changes in cochlea that restrict blood supply to neural elements?)restrict blood supply to neural elements?)

AuditionAudition

Conduction Hearing LossConduction Hearing Loss caused by damage to the mechanical caused by damage to the mechanical

system that conducts sound waves to the system that conducts sound waves to the cochlea (Ear drum, hammer, anvil, stirrup)cochlea (Ear drum, hammer, anvil, stirrup)

Nerve Hearing LossNerve Hearing Loss hearing loss caused by damage to the hearing loss caused by damage to the

cochlea’s receptor cells or to the auditory cochlea’s receptor cells or to the auditory nerve (hairs in basilar membrane not nerve (hairs in basilar membrane not regenerative)regenerative)

TinnitusTinnitus

Damage to auditory ear (ringing in ears)Damage to auditory ear (ringing in ears) Advanced case is incapacitatingAdvanced case is incapacitating Shell shock (combat zones)Shell shock (combat zones) tinnitus masker: “ocean waves or radio static”tinnitus masker: “ocean waves or radio static”

Helen KellerHelen Keller

What would be more difficult, being blind What would be more difficult, being blind or deaf?or deaf?

“…“…deafness to be a much greater deafness to be a much greater handicap than blindness… Blindness cuts handicap than blindness… Blindness cuts people off from things. Deafness cuts people off from things. Deafness cuts people off from people.”people off from people.”

Cochlear ImplantsCochlear Implants Nerve deafnessNerve deafness ““bionic ear”bionic ear” Stimulates sites on auditory nerveStimulates sites on auditory nerve

AuditionAudition Older people tend to hear low frequencies well Older people tend to hear low frequencies well

but suffer hearing loss for high frequenciesbut suffer hearing loss for high frequencies

1time

10times

100times

1000times

32 64 128 256 512 1024 2048 4096 8192 16384

Frequency of tone in waves per second

Low Pitch High

Amplitude required forperception relative to 20-29 year-old group

True or False?True or False?

1. Hard of hearing people need all sounds 1. Hard of hearing people need all sounds amplified.amplified.

2. Blind musicians are more likely than 2. Blind musicians are more likely than sighted ones to develop perfect pitch.sighted ones to develop perfect pitch.

3. Deaf people’s auditory cortex becomes 3. Deaf people’s auditory cortex becomes responsive to touch and visual input.responsive to touch and visual input.

Sensory Compensation / plasticitySensory Compensation / plasticity

TouchTouch Skin senses: pressure, warmth, cold, painSkin senses: pressure, warmth, cold, pain Which is the only sensation identifiable Which is the only sensation identifiable

with skin receptors?with skin receptors? PressurePressure

The Rubber hand illusion (demo)The Rubber hand illusion (demo)

TouchTouch

PainPain

Pain = sensation + brain + expectationPain = sensation + brain + expectation ““No brain, no pain”No brain, no pain” More complex / no More complex / no oneone stimulus / neural stimulus / neural

cord, no special receptorscord, no special receptors Research shows extent of pain is more Research shows extent of pain is more

influential than duration (medical influential than duration (medical procedures)procedures)

PainPain Gate-Control TheoryGate-Control Theory

Theory: Theory: spinal cord contains a spinal cord contains a neurological “gate” that blocks pain neurological “gate” that blocks pain signals or allows them to pass on to the signals or allows them to pass on to the brainbrain

Small nerve fibers: conduct pain signalsSmall nerve fibers: conduct pain signals Small nerve fibers open / activate neural Small nerve fibers open / activate neural

gategate Large nerve fibers close gate (shut off Large nerve fibers close gate (shut off

pain)pain)

Chronic PainChronic Pain Pain= physiological and psychologicalPain= physiological and psychological Treat by stimulating large neural fibers (to Treat by stimulating large neural fibers (to

close the gate…)close the gate…) Acupuncture, massage, electrical stimulation)Acupuncture, massage, electrical stimulation)

1 in 6 Americans:100 billion total expenses1 in 6 Americans:100 billion total expenses

Reactions to pain..Reactions to pain..

Why do we rub something when we hurt Why do we rub something when we hurt it?it? Create competing stimulation that will block Create competing stimulation that will block

some of the pain impulses… (“Makes it feel some of the pain impulses… (“Makes it feel better…”)better…”)

TasteTaste Taste SensationsTaste Sensations

sweetsweet soursour saltysalty BitterBitter UmamiUmami (meaty taste) monosodium glutamate (meaty taste) monosodium glutamate

Sensory InteractionSensory Interaction the principle that one sense may influence the principle that one sense may influence

anotheranother (all senses) (all senses) Ex: the smell of food influences its tasteEx: the smell of food influences its taste

Taste: A Chemical SenseTaste: A Chemical Sense Each bump on your tongue = 200 taste Each bump on your tongue = 200 taste

budsbuds Taste sensitivity decreases with ageTaste sensitivity decreases with age Sensory interaction: taste + texture +smell Sensory interaction: taste + texture +smell

= flavor= flavor

T-FT-F

You can taste without your tongue.You can taste without your tongue.

(Taste receptors in back and roof of mouth.)(Taste receptors in back and roof of mouth.)

New StudiesNew Studies Tongue and taste: Tongue and taste: Place theory outdatedPlace theory outdated Taste is comprehensive over tongueTaste is comprehensive over tongue

Senses Influence Each OtherSenses Influence Each Other…… Sensory InteractionSensory Interaction

the principle that one sense may influence the principle that one sense may influence another (all senses)another (all senses)

Ex: the smell of food influences its tasteEx: the smell of food influences its taste

Synaesthesia (“to perceive together”)Synaesthesia (“to perceive together”) joining of senses / one sense stimulates joining of senses / one sense stimulates

anotheranother Feels shapes when taste / smell foodFeels shapes when taste / smell food See colors in response to painSee colors in response to pain Most common: see numbers / letters in colorsMost common: see numbers / letters in colors Recent study: 1 in 2,000 - 1 male to 6 femaleRecent study: 1 in 2,000 - 1 male to 6 female Theory: cross-activation of adjacent brain Theory: cross-activation of adjacent brain

regions regions

SmellSmell

OlfactionOlfaction A chemical senseA chemical sense ProcessProcess

Molecules of substance / air / 5 million receptor Molecules of substance / air / 5 million receptor cells @ top of each nasal cavitycells @ top of each nasal cavity

Impulse sent to brain through axon fibersImpulse sent to brain through axon fibers Odors recognized individuallyOdors recognized individually Odor molecules / neural receptors (key and lock)Odor molecules / neural receptors (key and lock) 10,000 odors detected! Peak at early adulthood10,000 odors detected! Peak at early adulthood Olfactory bulb > amygdala > hippocampus > Olfactory bulb > amygdala > hippocampus >

cortex (why smell evokes emotions, memoriescortex (why smell evokes emotions, memories))

SmellSmell

Receptor cells inolfactory membrane

Nasal passage

Olfactorybulb

Olfactorynerve

Gender and SensesGender and Senses Detecting men from women: smell Detecting men from women: smell Research confirms: “hands, breath and shirts”- Research confirms: “hands, breath and shirts”- can distinguish the genders (can distinguish the genders (pheromonespheromones)) Women better “sniffers” than menWomen better “sniffers” than men

Age, Sex and Sense of Age, Sex and Sense of SmellSmell

Women

Men

10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 90-99Age Group

4

3

2

0

Numberof correct

answers

Women and young adults have best sense of smell

Body Position and MovementBody Position and Movement(Sensorimotor Coordination)(Sensorimotor Coordination)

KinesthesisKinesthesis the system for sensing the position and the system for sensing the position and

movement of individual body partsmovement of individual body parts Vestibular SenseVestibular Sense

Monitors head (and thus bodies) movementMonitors head (and thus bodies) movement Sense of balanceSense of balance (equalibrium) (equalibrium) Inner ear: semicircular canals, vestibular Inner ear: semicircular canals, vestibular

sacs = fluid = hair-like receptors = impulse sacs = fluid = hair-like receptors = impulse to cerebellum (Vertigo)to cerebellum (Vertigo)

Make sense now…?Make sense now…?