physics 1251 the science and technology of musical sound unit 2 session 12 mwf the human ear unit 2...
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Physics 1251Physics 1251The Science and The Science and
Technology of Musical Technology of Musical SoundSound
Physics 1251Physics 1251The Science and The Science and
Technology of Musical Technology of Musical SoundSound
Unit 2Unit 2
Session 12 MWFSession 12 MWF
The Human EarThe Human Ear
Unit 2Unit 2
Session 12 MWFSession 12 MWF
The Human EarThe Human Ear
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Foolscap Quiz:Foolscap Quiz:A student guitarist plays a chord on his electric A student guitarist plays a chord on his electric
guitar. When he mutes the strings he notices guitar. When he mutes the strings he notices that his acoustic guitar on the rack beside the that his acoustic guitar on the rack beside the amplifier is also ringing. What is the name of amplifier is also ringing. What is the name of the relevant effect and what is happening?the relevant effect and what is happening?
Resonance. The strings of the acoustic Resonance. The strings of the acoustic guitar were tuned to some frequency that guitar were tuned to some frequency that he played. The strings picked up the he played. The strings picked up the energy from the vibrations of the air that energy from the vibrations of the air that were “in resonance.”were “in resonance.”
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Ludwig van BeethovenLudwig van Beethoven(1770-1827)(1770-1827)
9 th Symphony (Choral)9 th Symphony (Choral)Composed when heComposed when hewas profoundly deaf.was profoundly deaf.
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
11′ Lecture:′ Lecture:The The human earhuman ear is a highly sensitive is a highly sensitive
sound receptor in which sound receptor in which • pressure fluctuations in the outer ear pressure fluctuations in the outer ear
are transformed are transformed • into vibrations of small bones (the into vibrations of small bones (the
ossicles) in the middle ear ossicles) in the middle ear • that are ultimately communicated to that are ultimately communicated to
the cochlea located in the inner ear, the cochlea located in the inner ear, • where the vibrations are further where the vibrations are further
transformed by stereocilia (hair cells) transformed by stereocilia (hair cells) • into neural impulses distributed by into neural impulses distributed by
frequency.frequency.
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Anatomy of EarAnatomy of Ear
Outer Outer EarEar
Middle Middle EarEar
Inner Inner EarEar
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Anatomy of the EarAnatomy of the Ear• 80/2080/20Outer Ear:Outer Ear:
1.1. Pinna – (the feather) matches Pinna – (the feather) matches ear canal to outside world.ear canal to outside world.
2.2. Meatus – ( the passageway) Meatus – ( the passageway) conducts conducts sound into head.sound into head.
3. Tympanium – (the drum) 3. Tympanium – (the drum) transforms transforms pressure fluctuations pressure fluctuations into displacement.into displacement.
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Outer EarOuter Ear
• Pinna Pinna ——→——→
• Meatus Meatus ———→———→←— ←— TympaniumTympanium
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Anatomy of EarAnatomy of Ear
Middle EarMiddle Ear
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Anatomy of the EarAnatomy of the Ear• 80/2080/20Middle Ear: The OssiclesMiddle Ear: The Ossicles
(little bones)(little bones)1.1. Malleus Malleus ―― (the hammer) moved (the hammer) moved
by Tympanium.by Tympanium.
2.2. Incus Incus ―― (the anvil) supported (the anvil) supported by ligaments by ligaments that protect against that protect against loud percussion.loud percussion.3. Stapes 3. Stapes ―― (the stirrup) force (the stirrup) force multiplied by multiplied by 1.3 because of 1.3 because of lever action.lever action.
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Tympanic Membrane (Ear Drum) Tympanic Membrane (Ear Drum)
micrographmicrograph
((view from view from inside)inside)
←————— ←————— TympamiumTympamium←——— ←——— Malleus and Malleus and
ligamentsligaments
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
The OssiclesThe Ossicles
Malleus Malleus ————→→
←—— ←—— IncusIncus
←—— ←—— StapesStapes
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
OssiclesOssicles(Micrographs)(Micrographs)
MalleusMalleusIncusIncus
StapeStapess
MalleusMalleus IncusIncus
StapesStapesTympaniTympaniumum
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Anatomy of EarAnatomy of Ear
Inner EarInner Ear
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Anatomy of the EarAnatomy of the Ear• 80/2080/20Inner Ear: Inner Ear:
Cochlea – (the Snail) converts Cochlea – (the Snail) converts displacement into neural displacement into neural impulsesimpulses..Auditory Nerve – neural Auditory Nerve – neural
impulses to impulses to brainbrain
Semicircular canals – detect Semicircular canals – detect motion motion and orientationand orientation
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Anatomy of Inner EarAnatomy of Inner Ear
←—— ←—— Semicircular Semicircular CanalsCanals
←—— ←—— CochleaCochlea
Oval Oval WindowWindow
Round Round WindowWindow
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
CCochleaochlea(micrograph)(micrograph)““The SnThe Snail”ail”
• o~ oval windowo~ oval window• r~ round windowr~ round window
2 mm2 mm
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Structure of CochleaStructure of Cochlea
1. Spiral cone1. Spiral cone2. Divided by2. Divided by Basilar Basilar Membrane Membrane
3. In on top 3. In on top halfhalf
4. Out on 4. Out on bottombottom
5. “Sloshing “5. “Sloshing “
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Anatomy of CochleaAnatomy of Cochlea
MicrographMicrographSectionSection
Basilar Basilar ————————————→ → MembraneMembrane
© Kansas State School of Medicine© Kansas State School of Medicine
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Microstructure Microstructure
of Cochleaof Cochlea
Basilar Basilar ——————→ ——————→ MembraneMembrane
↑↑
Organ of Organ of CortiCortiAuditory Nerve Auditory Nerve → →
→→
↑↑
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Stereocilia (Hair Cells)Stereocilia (Hair Cells)
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Outer Hair Cell in Cross SectionOuter Hair Cell in Cross Section
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Inner Hair CellsInner Hair Cells
Afferent Afferent
EfferentEfferent
Synapse ⇘
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Organ of Corti and Basilar MembraneOrgan of Corti and Basilar Membrane
OuterOuter ←——— ←——— Hair Hair CellsCells
←————— ←————— Inner Hair Inner Hair CellsCells
Vibration Vibration
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Detail of Hair CellDetail of Hair Cell
StereociliaStereocilia
Vibration Vibration ))))))))
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Action of Hair CellAction of Hair Cell
Hair CellHair CellDepolarizesDepolarizesNeurotransmittNeurotransmitt
er releaseder released
Hair CellHair CellNerveNerve
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Function of StereociliaFunction of Stereocilia
Stimulation Stimulation
in HCin HC
Causes neuro-Causes neuro-
transmitter totransmitter to
stimulate neuronstimulate neuron
in Auditory Nervein Auditory Nerve
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Frequency Response of Hair CellsFrequency Response of Hair Cells
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Frequency Discrimination in CochleaFrequency Discrimination in Cochlea• 20 Hz to 20 kHz (typical in Humans)20 Hz to 20 kHz (typical in Humans)
• Resonances in Basilar membrane and in Resonances in Basilar membrane and in HC cause spatial separation by HC cause spatial separation by frequency.frequency.
• Differential movement of membranes Differential movement of membranes stimulate HC.stimulate HC.
• Minimum stimulation required for Minimum stimulation required for response. Inhibition of neighbors response. Inhibition of neighbors causes non-linear response.causes non-linear response.
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Neuronal Decoding of Sound Neuronal Decoding of Sound (Schematic)(Schematic)
Frequency Frequency response response
localized in localized in CochleaCochlea
High Frequency
Low Frequency
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Neuronal Response to SoundNeuronal Response to Sound
• FrequencyFrequency → → WhereWhere? The location ? The location where in the Cochlea the where in the Cochlea the
stereocilia stereocilia are stimulated.are stimulated.• IntensityIntensity → → How manyHow many? The ? The
number of number of HC that are stimulated HC that are stimulated by the sound by the sound determines the determines the perceived loudness.perceived loudness.
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
80/2080/20Repeated acoustic trauma can Repeated acoustic trauma can cause permanent and profound cause permanent and profound hearing loss or deafness.hearing loss or deafness.
If you have experienced temporaryIf you have experienced temporary
hearing loss due to loud soundshearing loss due to loud sounds
you have had a warning.you have had a warning.
Stereocilia do regenerate daily.Stereocilia do regenerate daily.
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Hearing Loss due to Over Stimulation Hearing Loss due to Over Stimulation
causes Excitotoxicitycauses Excitotoxicity
Too much CaToo much Ca2+2+ poisons the neuron.poisons the neuron.
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Extreme Acoustic TraumaExtreme Acoustic Trauma
Control, not Control, not exposedexposed
After After ExposureExposure
Guinea Pig Stereocilia damage (120 dB Guinea Pig Stereocilia damage (120 dB sound)sound)
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
How do you protect yourself?How do you protect yourself?
Ear PlugsEar PlugsWear Wear Them!Them!
Wear Them!Wear Them!Wear Them!Wear Them!
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
How does Anatomy affect perception?How does Anatomy affect perception?
• Frequency responseFrequency response• Loudness perceptionLoudness perception• Phase insensitivityPhase insensitivity• DeafnessDeafness
• Disruption of “acoustic chain.”Disruption of “acoustic chain.”• Nerve death.Nerve death.
• RemediesRemedies• Restore chain or increase amplitudeRestore chain or increase amplitude
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
Summary:Summary:
Anatomy : Outer, Middle and Inner Anatomy : Outer, Middle and Inner Ear.Ear.
Function: Function: Outer Outer – converts pressure fluctuations – converts pressure fluctuations
to displacement.to displacement.
Middle Middle – amplifies displacement, – amplifies displacement, protects against loud noise.protects against loud noise.
Inner Inner – converts displacement to neural – converts displacement to neural impulses, sorted by frequency. impulses, sorted by frequency.
Physics 1251Physics 1251 Unit 2 Session 12Unit 2 Session 12The Human EarThe Human Ear
• Physiology determines function.Physiology determines function.
• No phase detection mechanism.No phase detection mechanism.
• Large “non-linear” range of 12 orders of Large “non-linear” range of 12 orders of magnitude in intensitymagnitude in intensity
• Three (3) orders of magnitude in Three (3) orders of magnitude in frequency (20 Hz to 20 kHz).frequency (20 Hz to 20 kHz).
• Trauma (due to loud sounds) is a cause Trauma (due to loud sounds) is a cause of deafness.of deafness.