SlideShare una empresa de Scribd logo
1 de 64
Descargar para leer sin conexión
BY
MD.ROOHIA
 It is a form of energy

produced by a vibrating
object.
 A sound wave consists of
compression and rarefaction
of molecules of the medium
in which it travels.
 Sound wave shows variations
in pressure of the air, and the
velocity and displacement of
molecules.
 When pressure of wave is at a
maximum, the forward
velocity of air molecules is
also at a maximum.

Graphic representations of a sound wave. (A) Air at
equilibrium, in the absence of a sound wave; (B)
compressions and rarefactions that constitute a
sound wave; (C) transverse representation of the
wave, showing amplitude (A) and wavelength (λ).
 Frequency
 Intensity
 Frequency is the number of cycles per second.
 The wavelength of sound is the distance between

analogous points of two successive waves.
 Unit of frequency is hertz (Hz).
 If the frequency of a wave is f cycles/s (Hz), then f
waves must pass any point in one sec
 Frequencies of 500, 1000

and 2000 Hz are called
speech frequencies as most
of human voice fall within
this range.
 PTA (Pure Tone Average) is
the average threshold of
hearing in these three
speech frequencies.
 Normal hearing frequency
range is 20 to 20,000Hz
 Routine in audiometric
testing only 125 to 8000Hz
evaluated
 It is the strength of the sound which determines its

loudness.
 It is usually measured by decibels.
 It is 1/10th of a bel.
 It is named after Alexander Graham Bell
 Sound can be measured as power (watts/cm2) or as

pressure (dynes/cm2) or in physical units (N/m2 or
pascals).
 Decibel notation was introduced in audiology to avoid
dealing with large figures of sound pressure level.
 In audiology sound is measured as sound pressure
level (SPL).
 The SPL of a sound in

decibels is 20 times the
logarithm to the base 10, of
the pressure of a sound to
the reference pressure.
 The reference pressure is
taken as 0.0002
dynes/cm2or 20µPa for a
frequency of 1000 Hz and
represents the threshold of
hearing in normally
hearing young adults.
 A single frequency sound

is called a pure tone.
 Sound with more than

one frequency is called a
complex sound.
 It is a subjective sensation produced by frequency of

sound.
 Higher the frequency, greater is the pitch.
 A complex sound has a fundamental frequency i.e., the

lowest frequency at which a source vibrates.
 All the frequencies above that tone are called
overtones.
 Overtones determine the quality or timbre of sound.
 It is the subjective sensation produced by intensity.
 More the intensity of the sound, greater the loudness.
 It is defined as an aperiodic complex

sound.
 There are 3 types of noise:

 White noise – contains all

frequencies in audible spectrum. It
is a broad band noise and used for
masking.
 Narrow band noise – white noise
with certain frequencies, above
and below the given noise filtered
out. Frequency range is smaller
than the broad band white noise.
It is used to mask test frequency in
pure tone audiometry.
 Speech noise – noise having
frequencies in the speech range
(300-3000 Hz). All other
frequencies are filtered out.
 Audiometric zero is the mean value of minimum

audible intensity in a group of normally hearing
healthy young adults.
 It is the sound pressure level produced by an

audiometer at a specific frequency.
 It is measured in decibels with reference to
audiometric zero.
 It is the level of sound above the threshold of hearing

for an individual.
 Sensation level refers to the sound which will produce
the same sensation, as in a normally hearing person.
 Intensity (Loudness) level of sound that is most

comfortable for the person.
 Level of sound which produces discomfort in the ear.
 It is usually 90 – 105 dB SL.
 It is important to find the loudness discomfort level of

a person when prescribing a hearing aid.
 ATTENUATION BY

DISTANCE.
 Propagation of sound is
like a ripples on pond.
 Dicreases in amplitude
as they move away from
the source.
 For sound if distance
doubles amp drops by
half.
 Transmission between different media
 Air is light and compressible, only small sound pressures

will be needed to give a certain velocity of vibration, and
hence displacement of air molecules.
 In a medium with higher impedance the pressure will be
inadequate to give similar velocities of vibration.
 So when sound in air meets a medium of higher
impedance it can not produce same amount of vibration
in that medium, so the result is much of the sound is
reflected with only small proportion being transmitted.
 The analysis of the complex

sound into its constituent
sinusoids is known as
FOURIER ANALYSIS.
 Any realistic waveforms
can be made out of sums of
sinusoids.
 Sinusoidal sound behave in
a simple way in many
complex environments.
 Cochlea itself performs
Fourier Analysis.
 Sound just a

combination of sine
functions.
 We can assign each sinefunction,&therefore the
original sound, to a
distinct energy or power
spectrum which gives us
the
energy/amplitude/freq.
 This process called FT.
 Open on one end only.
 The impedance of ear

drum is around 3 to 4 times
more than air.
 30% of incident sound
energy is reflected from
external canal.
 It is efficient in conducting
sound in frequency range
of 3 to 5 kHz.
 It cuts off unwanted
frequencies helping in
better speech
discrimination.
 It acts as a resonator.
 It increases the pressure at the ear drum in a frequency

sensitive way.
 Helps in localization of sound.
 Its length is 28mm.
 If a tube of one quarter wave length long and one end

is open and the other end is blocked with hard
termination, the pressure will be low at the open end
and high at the closed end when the tube is placed in a
sound field.
 This phenomenon is seen in human external meatus at
frequency of 3 kHz, resonance adds 10 to 12 dB at the
tympanic membrane.
 Both sound pressure

levels and phase of
acoustic waves are
important factors in
sound localization.
 Maximum time
difference (phase
difference) between two
ears is 750 milliseconds.
 It couples sound energy to

cochlea.
 It serves as an acoustic
transformer to match the
impedance of air to
cochlear fluids.
 It couples sound
preferentially to only one
window, thus producing a
differential pressure
between the windows
required for movement of
cochlear fluids.
1)





CATENARY LEVER(ear
drum)
Buckling mechanism of
TM
Force is transmitted from
centre of TM.
TM memb doesn’t move
as a plate.
This causes high pressure
with low displacement.
2.OSSICULAR
LEVER(lever ratio):
 Length of the handle of
malleus 1.3 times longer
than long process of
incus.
3.HYDRAULIC
LEVER(areal ratio):
 Average area of TM is
larger(60mmsq0 than
foot plate
area(3.2mmsq)(OW).
 Effective vibratory area of
TM 65% that is 45mmsq.
Roohia
 Only 65% of sound

energy from TM gets
absorbed and
transmitted to the
cochlea.
 Without middle ear only
1% of the sound energy
will be absorbed by the
cochlea.
 Tensor tympani attaches to

the handle of malleus. It
pulls the drum medially.
 Stapedius muscle attaches
to the posterior aspect of
stapes.
 Contraction of these
muscles increases the
stiffness of ossicular chain
thus blunting low
frequencies.
 These muscles decreases a
person’s sensitivity to their
own speech.
 Stapedius contraction can

reduce transmission up to
30dB for frequencies less
than 1 to 2 kHz. For higher
frequencies it is limited to
10dB.
 Only stapedius muscle
contracts in response to
loud noise in humans.
 The whole stapedial reflex
arc has 3 to 4 synapses.
 Stapedial reflex latency is 6
to 7 ms.
 Damaged middle ear can cause loss of transformer

mechanism.
 Differential pressure levels between the two windows
could not be maintained.
 Scala vestibuli is more yielding than scala tympani.
Differential movements of fluid with in the cochlea is
still possible.
 Small compliance of annular ligament in comparison
to much larger compliant round window could again
cause differential pressure.
 Normal route for hearing

one’s own voice.
 Useful in cases of severe
conductive losses.
 Can be used as a
diagnostic tool.
 Intrinsic detection of








distortional vibrations of
cochlear bone.
Differential distortion of bony
structures of cochlea (scala
vestibuli is larger than scala
tympani) could cause
movement of cochlear fluids.
Direct vibration of osseous
spiral lamina.
Direct transmission of
vibrations from the skull via
CSF to the cochlear fluids.
Leaving one window open
improved sound conduction.
 Vibrations of the skull gets

faithfully transmitted to
the ossicles of middle ear
cavity.
 Inertia of the middle ear
ossicles doesn’t coincide
with their points of
attachments.
 Middle ear acts as a band
pass filter with peak
transmission around 1kHz.
 This accounts of carhart’s
notch though at a slightly
higher frequency.
 Bone vibrations are

conducted through the
external canal and the air
within it.
 Vibrations can escape
externally if the canal is
open.
 Occlusion of external ear
increases bone conduction.
 External radiation of sound
is best for low
frequencies, hence change
with occlusion is greatest
for these frequencies.
 Scala vestibuli and scala tympani






contains perilymph.
Scala media contains
endolymph.
Perilymph space opens into CSF
via cochlear aqueduct.
Endolymphatic space joins the
endolymphatic sac by
endolymphatic duct.
Scala vestibuli is separated from
scala media by reissner’s
membrane. It is very thin and
does not obstruct the passage of
sound from s. vestibuli to s.
media. They may even be
considered to be a single
chamber.
 Formed by stria vascularis.
 Endolymphatic sac

maintains homeostasis of
endolymph.
 It has high potassium and
low sodium content.
 Endolymph has positive
potential gradient +50 to
120mV (endocochlear
potential).
 Na K ATPase is responsible
for this gradient.
 Secretes Endolymph.
 Superficial dark staining

marginal cells.
 Lightly staining basal
cells.
 Marginal cells are
secretory in nature.
 Site of production is







controversial - ? CSF
Occupies perilymphatic space.
Continuous between vestibular
and cochlear divisions.
Ionic concentration resembles
extracellular fluid.
Perilymph from s. vestibuli
originates from plasma, while
perilymph from s. tympani
originates from both plasma and
CSF.
Electrical potential from s.
tympani is +7mV and from s.
vestibuli is +5mV.
 It separates s. media from s.








tympani.
Length’s of basillar membrane
increases from oval window to the
apex (0.04mm near oval window
and 0.5mm at helicotrema) 12 folds
increase.
Diameters of basilar fibers decrease
from oval window to helicotrema.
The stiff short fibers near the oval
window vibrate best at very high
frequency, while long limber fibers
near the tip of cochlea vibrate best at
a low frequency.
It is known as tonotopic
presentaion.
 By the movement of

ossicles sound wave
reaches through oval
window to cochlea.
 Here the fluid in sv &st set
in motion as well as BM.
 BM moved by travelling
wave.
 Location of max amplitude
of this wave depends on
freq of incomming sound
signal,here freq analysis
take place.
 BM movts leads to

stimulation of nerve cells
In OC, & send electrical
impulses to brain&
sound percieved.
 BM movt is amplified by
OHC called active
amplification.
 Low input signals evoke
larger BM displacements
than high sound levels.
 When the steriocilia are

deflected in the direction
of the tallest steriocilia,
the links are stretched
opening up calcium
channels.
 Makes large number of synaptic









contact with afferent fibers of
auditory nerve.
95% of afferent auditory nerves
make contact with inner hair cells.
Detects basillar membrane
movements.
Tips of inner hair cells are not
embedded in the tectorial
membrane as outer hair cells.
They fit loosely into a groove called
“Henson’s stripe”.
The cilia are driven by vicious drag
of endolymph.
Inner hair cells respond to the
velocity rather than displacement.
 Very few outer hair cells








synapse with auditory
nerves.
Inside of outer hair cells
have -70mV.
They serve to amplify
basillar membrane
vibration.
They increase the
sensitivity and selectivity
of cochlea.
Cochlear microphonics are
derived from these cells.
 Cochlear microphonics –

A/C
 Summating potential –
D/C
 Negative neutral
potentials – N1 & N2
 Inner hair cells excite auditory nerves.
 Single auditory stimulus is always excitatory.
 Sound stimulus, transmitter release and action

potential generation occur in synchrony (Phase L
 ocking). Commonly seen in low frequency.
 Timing AP in the nerve is able to signal details of the
temporal properties of the sound wave form is called
TEMPORAL CODING.
 Coding based on frequency selectivity is called PLACE
CODING.
Roohia
AUDITORY PATHWAY
 Signals from both ears are

transmitted to both sides
of the brain.
 Preponderance of
transmission in
contralateral pathway.
 Three cross over points are:
 In the trapezoid body.
 In the commisure between

the two nuclei of lateral
lemnisci.
 In the commisure
connecting the two
inferior colliculi.
 Sound localization and lateralization
 Auditory discrimination
 Temporal aspects of audition including
 Temporal resolution
 Temporal masking
 Temporal integration
 Temporal ordering
 Auditory performance with competing acoustic signals
 Auditory performance with degraded signals.
Roohia
1st GROUP THEORIES
 Telephonic Theory Of Rutherford(1880)
 Volley Theory of Waver & Bray(1949)
2nd GROUP THEORIES
 Resonance Theory of Helmholtz(1883)
 Place Theory
 Travelling Wave Theory VonBekesy(1960)
 Rutherford proposed that the entire cochlea responds

as a whole to all frequencies instead of being activated
on a plate.
 Here the sounds of all frequencies are transmitted as
in a telephone cable and frequency analysis is
performed at a higher level (brain).
 Damage to certain portions of the cochlea can cause
preferential loss of hearing certain frequencies i.e., like
damage to the basal turn of cochlea causing inability
to hear high frequency sounds.
 This can not be explained by telephonic theory.
 Proposed by Wever &Bray(1949)
 Volleys means groups
 Impulses of frequency above 1000cyc/sec were

transmitted by diff group of nerve fibres
 Basilar memb acts as series

of tuned resonators as in
piano string
 Each pitch vibrate BM
particular to its own place.
 High freq at basal region,
loe at apical region.
 Individual resonators not
found in cochlea so its
modified to place theory.
 According to Helmholtz basillar membrane has

different segments that resonated to different
frequencies.
 Particular nerve fibre gives information frm org of
corti to regarding region to brain.
 Eg: boiler maker’s disease
 Proposed by Bekesy.
 This theory proposes

frequency coding to take
place at the level of
cochlea.
 High frequencies are
represented towards the
base while lower
frequencies are closer to
apex.
By MD.ROOHIA
MODERATOR
DR.JANARDHAN

Más contenido relacionado

La actualidad más candente (20)

SOUND AND HEARING
SOUND AND HEARINGSOUND AND HEARING
SOUND AND HEARING
 
Sound
SoundSound
Sound
 
Sound Waves
Sound WavesSound Waves
Sound Waves
 
Sound resounance
Sound resounanceSound resounance
Sound resounance
 
Sound waves
Sound wavesSound waves
Sound waves
 
Reflection of Sound Part 1
Reflection of Sound Part 1Reflection of Sound Part 1
Reflection of Sound Part 1
 
Exp SPA - Chp 15 Sound
Exp SPA - Chp 15 SoundExp SPA - Chp 15 Sound
Exp SPA - Chp 15 Sound
 
3.5 form 4 sound
3.5 form 4 sound3.5 form 4 sound
3.5 form 4 sound
 
Sound
SoundSound
Sound
 
Basic theory of sound
Basic theory of soundBasic theory of sound
Basic theory of sound
 
Sound fundamentals
Sound fundamentalsSound fundamentals
Sound fundamentals
 
Sound
SoundSound
Sound
 
Part 1
Part 1Part 1
Part 1
 
Sound
SoundSound
Sound
 
acoustics on human ear
acoustics on human earacoustics on human ear
acoustics on human ear
 
Lecture 3 b psychoacoustics of discriminating and identifying sounds
Lecture 3 b psychoacoustics of discriminating and identifying soundsLecture 3 b psychoacoustics of discriminating and identifying sounds
Lecture 3 b psychoacoustics of discriminating and identifying sounds
 
Sound that we HEAR!
Sound that we HEAR!Sound that we HEAR!
Sound that we HEAR!
 
Sound
SoundSound
Sound
 
Properties Of Sound
Properties Of SoundProperties Of Sound
Properties Of Sound
 
Us physics (4)
Us physics (4)Us physics (4)
Us physics (4)
 

Similar a Roohia

physiologyofhearingppt1autosaved-170322153846 (1).pptx
physiologyofhearingppt1autosaved-170322153846 (1).pptxphysiologyofhearingppt1autosaved-170322153846 (1).pptx
physiologyofhearingppt1autosaved-170322153846 (1).pptxAtishHaldar
 
Physiology of hearing ppt
Physiology of hearing pptPhysiology of hearing ppt
Physiology of hearing ppthumra shamim
 
Physiology of auditory system
Physiology of auditory systemPhysiology of auditory system
Physiology of auditory systemPrasanna Datta
 
Audio visual system principles #1
Audio visual system principles #1Audio visual system principles #1
Audio visual system principles #1Mohamed Jamal
 
Difference between ultrasonic and infrasonic sound.pdf
Difference between ultrasonic and infrasonic sound.pdfDifference between ultrasonic and infrasonic sound.pdf
Difference between ultrasonic and infrasonic sound.pdfTakshila Learning
 
An Introduction to Audio Principles
An Introduction to Audio Principles An Introduction to Audio Principles
An Introduction to Audio Principles Dr. Mohieddin Moradi
 
Physiology of Hearing by Dr. Sudin Kayastha
Physiology of Hearing by Dr. Sudin Kayastha Physiology of Hearing by Dr. Sudin Kayastha
Physiology of Hearing by Dr. Sudin Kayastha Sudin Kayastha
 
Pure Tone Audiometry
Pure Tone AudiometryPure Tone Audiometry
Pure Tone Audiometrymukulbabla
 
New microsoft office power point presentation (3)
New microsoft office power point presentation (3)New microsoft office power point presentation (3)
New microsoft office power point presentation (3)swpuri319
 
ultrasonic waves ... by آيه عبدالناصرمحمدزكي
ultrasonic waves ... by آيه عبدالناصرمحمدزكي ultrasonic waves ... by آيه عبدالناصرمحمدزكي
ultrasonic waves ... by آيه عبدالناصرمحمدزكي Ayah Abd-Elnasser
 
PHYSIOLOGY OF HEARING-ARNAV.pptx
PHYSIOLOGY OF HEARING-ARNAV.pptxPHYSIOLOGY OF HEARING-ARNAV.pptx
PHYSIOLOGY OF HEARING-ARNAV.pptxsubrat0002
 
Hearing fin
Hearing finHearing fin
Hearing finMUBOSScz
 
A project on sound by nikund
A project on sound by nikundA project on sound by nikund
A project on sound by nikundsheshank jain
 
Difference limens & wrap up of acoustics
Difference limens & wrap up of acousticsDifference limens & wrap up of acoustics
Difference limens & wrap up of acousticsbethfernandezaud
 

Similar a Roohia (20)

physiologyofhearingppt1autosaved-170322153846 (1).pptx
physiologyofhearingppt1autosaved-170322153846 (1).pptxphysiologyofhearingppt1autosaved-170322153846 (1).pptx
physiologyofhearingppt1autosaved-170322153846 (1).pptx
 
Physiology of hearing ppt
Physiology of hearing pptPhysiology of hearing ppt
Physiology of hearing ppt
 
Physiology of auditory system
Physiology of auditory systemPhysiology of auditory system
Physiology of auditory system
 
Audio visual system principles #1
Audio visual system principles #1Audio visual system principles #1
Audio visual system principles #1
 
Soundwaves
SoundwavesSoundwaves
Soundwaves
 
Difference between ultrasonic and infrasonic sound.pdf
Difference between ultrasonic and infrasonic sound.pdfDifference between ultrasonic and infrasonic sound.pdf
Difference between ultrasonic and infrasonic sound.pdf
 
Sound
SoundSound
Sound
 
An Introduction to Audio Principles
An Introduction to Audio Principles An Introduction to Audio Principles
An Introduction to Audio Principles
 
Physiology of Hearing by Dr. Sudin Kayastha
Physiology of Hearing by Dr. Sudin Kayastha Physiology of Hearing by Dr. Sudin Kayastha
Physiology of Hearing by Dr. Sudin Kayastha
 
Sound.ppt
Sound.pptSound.ppt
Sound.ppt
 
Pure Tone Audiometry
Pure Tone AudiometryPure Tone Audiometry
Pure Tone Audiometry
 
Noise_its_control.ppt
Noise_its_control.pptNoise_its_control.ppt
Noise_its_control.ppt
 
Lec 9
Lec 9Lec 9
Lec 9
 
New microsoft office power point presentation (3)
New microsoft office power point presentation (3)New microsoft office power point presentation (3)
New microsoft office power point presentation (3)
 
ultrasonic waves ... by آيه عبدالناصرمحمدزكي
ultrasonic waves ... by آيه عبدالناصرمحمدزكي ultrasonic waves ... by آيه عبدالناصرمحمدزكي
ultrasonic waves ... by آيه عبدالناصرمحمدزكي
 
PHYSIOLOGY OF HEARING-ARNAV.pptx
PHYSIOLOGY OF HEARING-ARNAV.pptxPHYSIOLOGY OF HEARING-ARNAV.pptx
PHYSIOLOGY OF HEARING-ARNAV.pptx
 
Hearing fin
Hearing finHearing fin
Hearing fin
 
A project on sound by nikund
A project on sound by nikundA project on sound by nikund
A project on sound by nikund
 
Difference limens & wrap up of acoustics
Difference limens & wrap up of acousticsDifference limens & wrap up of acoustics
Difference limens & wrap up of acoustics
 
Acoustic unit3
Acoustic unit3Acoustic unit3
Acoustic unit3
 

Más de Md Roohia

Tumours of oral cavity
Tumours of oral cavity Tumours of oral cavity
Tumours of oral cavity Md Roohia
 
COCHLEAR IMPLANTATION over view
COCHLEAR IMPLANTATION over viewCOCHLEAR IMPLANTATION over view
COCHLEAR IMPLANTATION over viewMd Roohia
 
Case series otogenic brain abcess
Case series otogenic brain abcessCase series otogenic brain abcess
Case series otogenic brain abcessMd Roohia
 
Case report vs with nf2
Case report vs with nf2Case report vs with nf2
Case report vs with nf2Md Roohia
 
Surgery for paediatric sleep apnea
Surgery for paediatric sleep apneaSurgery for paediatric sleep apnea
Surgery for paediatric sleep apneaMd Roohia
 
Rehabilitation after laryngectomy
Rehabilitation after laryngectomyRehabilitation after laryngectomy
Rehabilitation after laryngectomyMd Roohia
 
Ossiculoplasty
OssiculoplastyOssiculoplasty
OssiculoplastyMd Roohia
 
Occult primary mangmnt
Occult primary mangmntOccult primary mangmnt
Occult primary mangmntMd Roohia
 
Oral manifestations in systemic diseases
Oral manifestations in systemic diseasesOral manifestations in systemic diseases
Oral manifestations in systemic diseasesMd Roohia
 
NASO-ORBITO-ETHMOIDAL fracture and management
NASO-ORBITO-ETHMOIDAL fracture and managementNASO-ORBITO-ETHMOIDAL fracture and management
NASO-ORBITO-ETHMOIDAL fracture and managementMd Roohia
 
management of b/l vocal cord paralysis
management of b/l vocal cord paralysismanagement of b/l vocal cord paralysis
management of b/l vocal cord paralysisMd Roohia
 
Cochlear implantation
Cochlear implantationCochlear implantation
Cochlear implantationMd Roohia
 
Anatomy of temporal bone and skull base
Anatomy of temporal bone and skull baseAnatomy of temporal bone and skull base
Anatomy of temporal bone and skull baseMd Roohia
 
Local flaps in head & neack reconstruction
Local flaps in head & neack reconstructionLocal flaps in head & neack reconstruction
Local flaps in head & neack reconstructionMd Roohia
 
Neoplasms of nose and pns
Neoplasms of nose and pnsNeoplasms of nose and pns
Neoplasms of nose and pnsMd Roohia
 
Steroids in SSNHL
Steroids in SSNHLSteroids in SSNHL
Steroids in SSNHLMd Roohia
 
Pyriform sinus tumours principles of management
Pyriform sinus tumours principles of managementPyriform sinus tumours principles of management
Pyriform sinus tumours principles of managementMd Roohia
 
Intra operative monitoring facial nerve
Intra operative monitoring facial nerveIntra operative monitoring facial nerve
Intra operative monitoring facial nerveMd Roohia
 
Infratemporal fossa approaches
Infratemporal fossa approachesInfratemporal fossa approaches
Infratemporal fossa approachesMd Roohia
 
craniopharyngioma
 craniopharyngioma craniopharyngioma
craniopharyngiomaMd Roohia
 

Más de Md Roohia (20)

Tumours of oral cavity
Tumours of oral cavity Tumours of oral cavity
Tumours of oral cavity
 
COCHLEAR IMPLANTATION over view
COCHLEAR IMPLANTATION over viewCOCHLEAR IMPLANTATION over view
COCHLEAR IMPLANTATION over view
 
Case series otogenic brain abcess
Case series otogenic brain abcessCase series otogenic brain abcess
Case series otogenic brain abcess
 
Case report vs with nf2
Case report vs with nf2Case report vs with nf2
Case report vs with nf2
 
Surgery for paediatric sleep apnea
Surgery for paediatric sleep apneaSurgery for paediatric sleep apnea
Surgery for paediatric sleep apnea
 
Rehabilitation after laryngectomy
Rehabilitation after laryngectomyRehabilitation after laryngectomy
Rehabilitation after laryngectomy
 
Ossiculoplasty
OssiculoplastyOssiculoplasty
Ossiculoplasty
 
Occult primary mangmnt
Occult primary mangmntOccult primary mangmnt
Occult primary mangmnt
 
Oral manifestations in systemic diseases
Oral manifestations in systemic diseasesOral manifestations in systemic diseases
Oral manifestations in systemic diseases
 
NASO-ORBITO-ETHMOIDAL fracture and management
NASO-ORBITO-ETHMOIDAL fracture and managementNASO-ORBITO-ETHMOIDAL fracture and management
NASO-ORBITO-ETHMOIDAL fracture and management
 
management of b/l vocal cord paralysis
management of b/l vocal cord paralysismanagement of b/l vocal cord paralysis
management of b/l vocal cord paralysis
 
Cochlear implantation
Cochlear implantationCochlear implantation
Cochlear implantation
 
Anatomy of temporal bone and skull base
Anatomy of temporal bone and skull baseAnatomy of temporal bone and skull base
Anatomy of temporal bone and skull base
 
Local flaps in head & neack reconstruction
Local flaps in head & neack reconstructionLocal flaps in head & neack reconstruction
Local flaps in head & neack reconstruction
 
Neoplasms of nose and pns
Neoplasms of nose and pnsNeoplasms of nose and pns
Neoplasms of nose and pns
 
Steroids in SSNHL
Steroids in SSNHLSteroids in SSNHL
Steroids in SSNHL
 
Pyriform sinus tumours principles of management
Pyriform sinus tumours principles of managementPyriform sinus tumours principles of management
Pyriform sinus tumours principles of management
 
Intra operative monitoring facial nerve
Intra operative monitoring facial nerveIntra operative monitoring facial nerve
Intra operative monitoring facial nerve
 
Infratemporal fossa approaches
Infratemporal fossa approachesInfratemporal fossa approaches
Infratemporal fossa approaches
 
craniopharyngioma
 craniopharyngioma craniopharyngioma
craniopharyngioma
 

Último

Graham and Doddsville - Issue 1 - Winter 2006 (1).pdf
Graham and Doddsville - Issue 1 - Winter 2006 (1).pdfGraham and Doddsville - Issue 1 - Winter 2006 (1).pdf
Graham and Doddsville - Issue 1 - Winter 2006 (1).pdfAnhNguyen97152
 
Ethical stalking by Mark Williams. UpliftLive 2024
Ethical stalking by Mark Williams. UpliftLive 2024Ethical stalking by Mark Williams. UpliftLive 2024
Ethical stalking by Mark Williams. UpliftLive 2024Winbusinessin
 
Developing Coaching Skills: Mine, Yours, Ours
Developing Coaching Skills: Mine, Yours, OursDeveloping Coaching Skills: Mine, Yours, Ours
Developing Coaching Skills: Mine, Yours, OursKaiNexus
 
Plano de marketing- inglês em formato ppt
Plano de marketing- inglês  em formato pptPlano de marketing- inglês  em formato ppt
Plano de marketing- inglês em formato pptElizangelaSoaresdaCo
 
A flour, rice and Suji company in Jhang.
A flour, rice and Suji company in Jhang.A flour, rice and Suji company in Jhang.
A flour, rice and Suji company in Jhang.mcshagufta46
 
Harvard Business Review.pptx | Navigating Labor Unrest (March-April 2024)
Harvard Business Review.pptx | Navigating Labor Unrest (March-April 2024)Harvard Business Review.pptx | Navigating Labor Unrest (March-April 2024)
Harvard Business Review.pptx | Navigating Labor Unrest (March-April 2024)tazeenaila12
 
Amazon ppt.pptx Amazon about the company
Amazon ppt.pptx Amazon about the companyAmazon ppt.pptx Amazon about the company
Amazon ppt.pptx Amazon about the companyfashionfound007
 
Intellectual Property Licensing Examples
Intellectual Property Licensing ExamplesIntellectual Property Licensing Examples
Intellectual Property Licensing Examplesamberjiles31
 
Personal Brand Exploration Presentation Eric Bonilla
Personal Brand Exploration Presentation Eric BonillaPersonal Brand Exploration Presentation Eric Bonilla
Personal Brand Exploration Presentation Eric BonillaEricBonilla13
 
Trauma Training Service for First Responders
Trauma Training Service for First RespondersTrauma Training Service for First Responders
Trauma Training Service for First RespondersBPOQe
 
Borderless Access - Global B2B Panel book-unlock 2024
Borderless Access - Global B2B Panel book-unlock 2024Borderless Access - Global B2B Panel book-unlock 2024
Borderless Access - Global B2B Panel book-unlock 2024Borderless Access
 
Upgrade Your Banking Experience with Advanced Core Banking Applications
Upgrade Your Banking Experience with Advanced Core Banking ApplicationsUpgrade Your Banking Experience with Advanced Core Banking Applications
Upgrade Your Banking Experience with Advanced Core Banking ApplicationsIntellect Design Arena Ltd
 
NASA CoCEI Scaling Strategy - November 2023
NASA CoCEI Scaling Strategy - November 2023NASA CoCEI Scaling Strategy - November 2023
NASA CoCEI Scaling Strategy - November 2023Steve Rader
 
NewBase 25 March 2024 Energy News issue - 1710 by Khaled Al Awadi_compress...
NewBase  25 March  2024  Energy News issue - 1710 by Khaled Al Awadi_compress...NewBase  25 March  2024  Energy News issue - 1710 by Khaled Al Awadi_compress...
NewBase 25 March 2024 Energy News issue - 1710 by Khaled Al Awadi_compress...Khaled Al Awadi
 
Team B Mind Map for Organizational Chg..
Team B Mind Map for Organizational Chg..Team B Mind Map for Organizational Chg..
Team B Mind Map for Organizational Chg..dlewis191
 
Data skills for Agile Teams- Killing story points
Data skills for Agile Teams- Killing story pointsData skills for Agile Teams- Killing story points
Data skills for Agile Teams- Killing story pointsyasinnathani
 
Cracking the ‘Business Process Outsourcing’ Code Main.pptx
Cracking the ‘Business Process Outsourcing’ Code Main.pptxCracking the ‘Business Process Outsourcing’ Code Main.pptx
Cracking the ‘Business Process Outsourcing’ Code Main.pptxWorkforce Group
 
Entrepreneurship & organisations: influences and organizations
Entrepreneurship & organisations: influences and organizationsEntrepreneurship & organisations: influences and organizations
Entrepreneurship & organisations: influences and organizationsP&CO
 
Lecture_6.pptx English speaking easyb to
Lecture_6.pptx English speaking easyb toLecture_6.pptx English speaking easyb to
Lecture_6.pptx English speaking easyb toumarfarooquejamali32
 

Último (20)

Graham and Doddsville - Issue 1 - Winter 2006 (1).pdf
Graham and Doddsville - Issue 1 - Winter 2006 (1).pdfGraham and Doddsville - Issue 1 - Winter 2006 (1).pdf
Graham and Doddsville - Issue 1 - Winter 2006 (1).pdf
 
Ethical stalking by Mark Williams. UpliftLive 2024
Ethical stalking by Mark Williams. UpliftLive 2024Ethical stalking by Mark Williams. UpliftLive 2024
Ethical stalking by Mark Williams. UpliftLive 2024
 
Developing Coaching Skills: Mine, Yours, Ours
Developing Coaching Skills: Mine, Yours, OursDeveloping Coaching Skills: Mine, Yours, Ours
Developing Coaching Skills: Mine, Yours, Ours
 
Plano de marketing- inglês em formato ppt
Plano de marketing- inglês  em formato pptPlano de marketing- inglês  em formato ppt
Plano de marketing- inglês em formato ppt
 
A flour, rice and Suji company in Jhang.
A flour, rice and Suji company in Jhang.A flour, rice and Suji company in Jhang.
A flour, rice and Suji company in Jhang.
 
Harvard Business Review.pptx | Navigating Labor Unrest (March-April 2024)
Harvard Business Review.pptx | Navigating Labor Unrest (March-April 2024)Harvard Business Review.pptx | Navigating Labor Unrest (March-April 2024)
Harvard Business Review.pptx | Navigating Labor Unrest (March-April 2024)
 
Amazon ppt.pptx Amazon about the company
Amazon ppt.pptx Amazon about the companyAmazon ppt.pptx Amazon about the company
Amazon ppt.pptx Amazon about the company
 
WAM Corporate Presentation Mar 25 2024.pdf
WAM Corporate Presentation Mar 25 2024.pdfWAM Corporate Presentation Mar 25 2024.pdf
WAM Corporate Presentation Mar 25 2024.pdf
 
Intellectual Property Licensing Examples
Intellectual Property Licensing ExamplesIntellectual Property Licensing Examples
Intellectual Property Licensing Examples
 
Personal Brand Exploration Presentation Eric Bonilla
Personal Brand Exploration Presentation Eric BonillaPersonal Brand Exploration Presentation Eric Bonilla
Personal Brand Exploration Presentation Eric Bonilla
 
Trauma Training Service for First Responders
Trauma Training Service for First RespondersTrauma Training Service for First Responders
Trauma Training Service for First Responders
 
Borderless Access - Global B2B Panel book-unlock 2024
Borderless Access - Global B2B Panel book-unlock 2024Borderless Access - Global B2B Panel book-unlock 2024
Borderless Access - Global B2B Panel book-unlock 2024
 
Upgrade Your Banking Experience with Advanced Core Banking Applications
Upgrade Your Banking Experience with Advanced Core Banking ApplicationsUpgrade Your Banking Experience with Advanced Core Banking Applications
Upgrade Your Banking Experience with Advanced Core Banking Applications
 
NASA CoCEI Scaling Strategy - November 2023
NASA CoCEI Scaling Strategy - November 2023NASA CoCEI Scaling Strategy - November 2023
NASA CoCEI Scaling Strategy - November 2023
 
NewBase 25 March 2024 Energy News issue - 1710 by Khaled Al Awadi_compress...
NewBase  25 March  2024  Energy News issue - 1710 by Khaled Al Awadi_compress...NewBase  25 March  2024  Energy News issue - 1710 by Khaled Al Awadi_compress...
NewBase 25 March 2024 Energy News issue - 1710 by Khaled Al Awadi_compress...
 
Team B Mind Map for Organizational Chg..
Team B Mind Map for Organizational Chg..Team B Mind Map for Organizational Chg..
Team B Mind Map for Organizational Chg..
 
Data skills for Agile Teams- Killing story points
Data skills for Agile Teams- Killing story pointsData skills for Agile Teams- Killing story points
Data skills for Agile Teams- Killing story points
 
Cracking the ‘Business Process Outsourcing’ Code Main.pptx
Cracking the ‘Business Process Outsourcing’ Code Main.pptxCracking the ‘Business Process Outsourcing’ Code Main.pptx
Cracking the ‘Business Process Outsourcing’ Code Main.pptx
 
Entrepreneurship & organisations: influences and organizations
Entrepreneurship & organisations: influences and organizationsEntrepreneurship & organisations: influences and organizations
Entrepreneurship & organisations: influences and organizations
 
Lecture_6.pptx English speaking easyb to
Lecture_6.pptx English speaking easyb toLecture_6.pptx English speaking easyb to
Lecture_6.pptx English speaking easyb to
 

Roohia

  • 2.  It is a form of energy produced by a vibrating object.  A sound wave consists of compression and rarefaction of molecules of the medium in which it travels.  Sound wave shows variations in pressure of the air, and the velocity and displacement of molecules.  When pressure of wave is at a maximum, the forward velocity of air molecules is also at a maximum. Graphic representations of a sound wave. (A) Air at equilibrium, in the absence of a sound wave; (B) compressions and rarefactions that constitute a sound wave; (C) transverse representation of the wave, showing amplitude (A) and wavelength (λ).
  • 4.  Frequency is the number of cycles per second.  The wavelength of sound is the distance between analogous points of two successive waves.  Unit of frequency is hertz (Hz).  If the frequency of a wave is f cycles/s (Hz), then f waves must pass any point in one sec
  • 5.  Frequencies of 500, 1000 and 2000 Hz are called speech frequencies as most of human voice fall within this range.  PTA (Pure Tone Average) is the average threshold of hearing in these three speech frequencies.  Normal hearing frequency range is 20 to 20,000Hz  Routine in audiometric testing only 125 to 8000Hz evaluated
  • 6.  It is the strength of the sound which determines its loudness.  It is usually measured by decibels.
  • 7.  It is 1/10th of a bel.  It is named after Alexander Graham Bell  Sound can be measured as power (watts/cm2) or as pressure (dynes/cm2) or in physical units (N/m2 or pascals).  Decibel notation was introduced in audiology to avoid dealing with large figures of sound pressure level.  In audiology sound is measured as sound pressure level (SPL).
  • 8.  The SPL of a sound in decibels is 20 times the logarithm to the base 10, of the pressure of a sound to the reference pressure.  The reference pressure is taken as 0.0002 dynes/cm2or 20µPa for a frequency of 1000 Hz and represents the threshold of hearing in normally hearing young adults.
  • 9.  A single frequency sound is called a pure tone.
  • 10.  Sound with more than one frequency is called a complex sound.
  • 11.  It is a subjective sensation produced by frequency of sound.  Higher the frequency, greater is the pitch.
  • 12.  A complex sound has a fundamental frequency i.e., the lowest frequency at which a source vibrates.  All the frequencies above that tone are called overtones.  Overtones determine the quality or timbre of sound.
  • 13.  It is the subjective sensation produced by intensity.  More the intensity of the sound, greater the loudness.
  • 14.  It is defined as an aperiodic complex sound.  There are 3 types of noise:  White noise – contains all frequencies in audible spectrum. It is a broad band noise and used for masking.  Narrow band noise – white noise with certain frequencies, above and below the given noise filtered out. Frequency range is smaller than the broad band white noise. It is used to mask test frequency in pure tone audiometry.  Speech noise – noise having frequencies in the speech range (300-3000 Hz). All other frequencies are filtered out.
  • 15.  Audiometric zero is the mean value of minimum audible intensity in a group of normally hearing healthy young adults.
  • 16.  It is the sound pressure level produced by an audiometer at a specific frequency.  It is measured in decibels with reference to audiometric zero.
  • 17.  It is the level of sound above the threshold of hearing for an individual.  Sensation level refers to the sound which will produce the same sensation, as in a normally hearing person.
  • 18.  Intensity (Loudness) level of sound that is most comfortable for the person.
  • 19.  Level of sound which produces discomfort in the ear.  It is usually 90 – 105 dB SL.  It is important to find the loudness discomfort level of a person when prescribing a hearing aid.
  • 20.  ATTENUATION BY DISTANCE.  Propagation of sound is like a ripples on pond.  Dicreases in amplitude as they move away from the source.  For sound if distance doubles amp drops by half.
  • 21.  Transmission between different media  Air is light and compressible, only small sound pressures will be needed to give a certain velocity of vibration, and hence displacement of air molecules.  In a medium with higher impedance the pressure will be inadequate to give similar velocities of vibration.  So when sound in air meets a medium of higher impedance it can not produce same amount of vibration in that medium, so the result is much of the sound is reflected with only small proportion being transmitted.
  • 22.  The analysis of the complex sound into its constituent sinusoids is known as FOURIER ANALYSIS.  Any realistic waveforms can be made out of sums of sinusoids.  Sinusoidal sound behave in a simple way in many complex environments.  Cochlea itself performs Fourier Analysis.
  • 23.  Sound just a combination of sine functions.  We can assign each sinefunction,&therefore the original sound, to a distinct energy or power spectrum which gives us the energy/amplitude/freq.  This process called FT.
  • 24.  Open on one end only.  The impedance of ear drum is around 3 to 4 times more than air.  30% of incident sound energy is reflected from external canal.  It is efficient in conducting sound in frequency range of 3 to 5 kHz.  It cuts off unwanted frequencies helping in better speech discrimination.
  • 25.  It acts as a resonator.  It increases the pressure at the ear drum in a frequency sensitive way.  Helps in localization of sound.  Its length is 28mm.
  • 26.  If a tube of one quarter wave length long and one end is open and the other end is blocked with hard termination, the pressure will be low at the open end and high at the closed end when the tube is placed in a sound field.  This phenomenon is seen in human external meatus at frequency of 3 kHz, resonance adds 10 to 12 dB at the tympanic membrane.
  • 27.  Both sound pressure levels and phase of acoustic waves are important factors in sound localization.  Maximum time difference (phase difference) between two ears is 750 milliseconds.
  • 28.  It couples sound energy to cochlea.  It serves as an acoustic transformer to match the impedance of air to cochlear fluids.  It couples sound preferentially to only one window, thus producing a differential pressure between the windows required for movement of cochlear fluids.
  • 29. 1)     CATENARY LEVER(ear drum) Buckling mechanism of TM Force is transmitted from centre of TM. TM memb doesn’t move as a plate. This causes high pressure with low displacement.
  • 30. 2.OSSICULAR LEVER(lever ratio):  Length of the handle of malleus 1.3 times longer than long process of incus.
  • 31. 3.HYDRAULIC LEVER(areal ratio):  Average area of TM is larger(60mmsq0 than foot plate area(3.2mmsq)(OW).  Effective vibratory area of TM 65% that is 45mmsq.
  • 33.  Only 65% of sound energy from TM gets absorbed and transmitted to the cochlea.  Without middle ear only 1% of the sound energy will be absorbed by the cochlea.
  • 34.  Tensor tympani attaches to the handle of malleus. It pulls the drum medially.  Stapedius muscle attaches to the posterior aspect of stapes.  Contraction of these muscles increases the stiffness of ossicular chain thus blunting low frequencies.  These muscles decreases a person’s sensitivity to their own speech.
  • 35.  Stapedius contraction can reduce transmission up to 30dB for frequencies less than 1 to 2 kHz. For higher frequencies it is limited to 10dB.  Only stapedius muscle contracts in response to loud noise in humans.  The whole stapedial reflex arc has 3 to 4 synapses.  Stapedial reflex latency is 6 to 7 ms.
  • 36.  Damaged middle ear can cause loss of transformer mechanism.  Differential pressure levels between the two windows could not be maintained.  Scala vestibuli is more yielding than scala tympani. Differential movements of fluid with in the cochlea is still possible.  Small compliance of annular ligament in comparison to much larger compliant round window could again cause differential pressure.
  • 37.  Normal route for hearing one’s own voice.  Useful in cases of severe conductive losses.  Can be used as a diagnostic tool.
  • 38.  Intrinsic detection of     distortional vibrations of cochlear bone. Differential distortion of bony structures of cochlea (scala vestibuli is larger than scala tympani) could cause movement of cochlear fluids. Direct vibration of osseous spiral lamina. Direct transmission of vibrations from the skull via CSF to the cochlear fluids. Leaving one window open improved sound conduction.
  • 39.  Vibrations of the skull gets faithfully transmitted to the ossicles of middle ear cavity.  Inertia of the middle ear ossicles doesn’t coincide with their points of attachments.  Middle ear acts as a band pass filter with peak transmission around 1kHz.  This accounts of carhart’s notch though at a slightly higher frequency.
  • 40.  Bone vibrations are conducted through the external canal and the air within it.  Vibrations can escape externally if the canal is open.  Occlusion of external ear increases bone conduction.  External radiation of sound is best for low frequencies, hence change with occlusion is greatest for these frequencies.
  • 41.  Scala vestibuli and scala tympani     contains perilymph. Scala media contains endolymph. Perilymph space opens into CSF via cochlear aqueduct. Endolymphatic space joins the endolymphatic sac by endolymphatic duct. Scala vestibuli is separated from scala media by reissner’s membrane. It is very thin and does not obstruct the passage of sound from s. vestibuli to s. media. They may even be considered to be a single chamber.
  • 42.  Formed by stria vascularis.  Endolymphatic sac maintains homeostasis of endolymph.  It has high potassium and low sodium content.  Endolymph has positive potential gradient +50 to 120mV (endocochlear potential).  Na K ATPase is responsible for this gradient.
  • 43.  Secretes Endolymph.  Superficial dark staining marginal cells.  Lightly staining basal cells.  Marginal cells are secretory in nature.
  • 44.  Site of production is     controversial - ? CSF Occupies perilymphatic space. Continuous between vestibular and cochlear divisions. Ionic concentration resembles extracellular fluid. Perilymph from s. vestibuli originates from plasma, while perilymph from s. tympani originates from both plasma and CSF. Electrical potential from s. tympani is +7mV and from s. vestibuli is +5mV.
  • 45.  It separates s. media from s.     tympani. Length’s of basillar membrane increases from oval window to the apex (0.04mm near oval window and 0.5mm at helicotrema) 12 folds increase. Diameters of basilar fibers decrease from oval window to helicotrema. The stiff short fibers near the oval window vibrate best at very high frequency, while long limber fibers near the tip of cochlea vibrate best at a low frequency. It is known as tonotopic presentaion.
  • 46.  By the movement of ossicles sound wave reaches through oval window to cochlea.  Here the fluid in sv &st set in motion as well as BM.  BM moved by travelling wave.  Location of max amplitude of this wave depends on freq of incomming sound signal,here freq analysis take place.
  • 47.  BM movts leads to stimulation of nerve cells In OC, & send electrical impulses to brain& sound percieved.  BM movt is amplified by OHC called active amplification.  Low input signals evoke larger BM displacements than high sound levels.
  • 48.  When the steriocilia are deflected in the direction of the tallest steriocilia, the links are stretched opening up calcium channels.
  • 49.  Makes large number of synaptic       contact with afferent fibers of auditory nerve. 95% of afferent auditory nerves make contact with inner hair cells. Detects basillar membrane movements. Tips of inner hair cells are not embedded in the tectorial membrane as outer hair cells. They fit loosely into a groove called “Henson’s stripe”. The cilia are driven by vicious drag of endolymph. Inner hair cells respond to the velocity rather than displacement.
  • 50.  Very few outer hair cells     synapse with auditory nerves. Inside of outer hair cells have -70mV. They serve to amplify basillar membrane vibration. They increase the sensitivity and selectivity of cochlea. Cochlear microphonics are derived from these cells.
  • 51.  Cochlear microphonics – A/C  Summating potential – D/C  Negative neutral potentials – N1 & N2
  • 52.  Inner hair cells excite auditory nerves.  Single auditory stimulus is always excitatory.  Sound stimulus, transmitter release and action potential generation occur in synchrony (Phase L  ocking). Commonly seen in low frequency.  Timing AP in the nerve is able to signal details of the temporal properties of the sound wave form is called TEMPORAL CODING.  Coding based on frequency selectivity is called PLACE CODING.
  • 55.  Signals from both ears are transmitted to both sides of the brain.  Preponderance of transmission in contralateral pathway.  Three cross over points are:  In the trapezoid body.  In the commisure between the two nuclei of lateral lemnisci.  In the commisure connecting the two inferior colliculi.
  • 56.  Sound localization and lateralization  Auditory discrimination  Temporal aspects of audition including  Temporal resolution  Temporal masking  Temporal integration  Temporal ordering  Auditory performance with competing acoustic signals  Auditory performance with degraded signals.
  • 58. 1st GROUP THEORIES  Telephonic Theory Of Rutherford(1880)  Volley Theory of Waver & Bray(1949) 2nd GROUP THEORIES  Resonance Theory of Helmholtz(1883)  Place Theory  Travelling Wave Theory VonBekesy(1960)
  • 59.  Rutherford proposed that the entire cochlea responds as a whole to all frequencies instead of being activated on a plate.  Here the sounds of all frequencies are transmitted as in a telephone cable and frequency analysis is performed at a higher level (brain).  Damage to certain portions of the cochlea can cause preferential loss of hearing certain frequencies i.e., like damage to the basal turn of cochlea causing inability to hear high frequency sounds.  This can not be explained by telephonic theory.
  • 60.  Proposed by Wever &Bray(1949)  Volleys means groups  Impulses of frequency above 1000cyc/sec were transmitted by diff group of nerve fibres
  • 61.  Basilar memb acts as series of tuned resonators as in piano string  Each pitch vibrate BM particular to its own place.  High freq at basal region, loe at apical region.  Individual resonators not found in cochlea so its modified to place theory.
  • 62.  According to Helmholtz basillar membrane has different segments that resonated to different frequencies.  Particular nerve fibre gives information frm org of corti to regarding region to brain.  Eg: boiler maker’s disease
  • 63.  Proposed by Bekesy.  This theory proposes frequency coding to take place at the level of cochlea.  High frequencies are represented towards the base while lower frequencies are closer to apex.