Hearing Problems - Test 1
Terms
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- Central Auditory System
- From Nucleus Complex to Cortex In the brain
- Peripheral Auditory System
- The part you can see 1. Outer Ear 2. Middle Ear 3. Inner Ear
- Parts of Outer Ear
- -Pinna - concha -Ear Canal
- External Auditory Meatus
- 20mm long Covered in epithelium Ceruminous glands
- External Ear Canal (portions and boundaries)
- cartilaginous (temporal, tympanic?) bony terminates in tympanic membrane
- Hammer
- aka Malleus bone embedded in tympanic membrane that moves along with it
- Middle Ear (parts)
- Ossicles: - Malleus - Incus - Stapes Footplate of Stapes Oval window
- Ossicles
- 2 synovial bones: Malleus Incus Stapes
- Oval window
- opening to the middle ear
- how do vibrations travel from outer ear to inner ear?
- footplate of stapes moving in oval window
- ventilation tube
- inserted by physicians to equalize the pressure between outer and inner ear
- middle ear muscles
- Tensor tympani, Stapedius
- Tensor tympani
- attached to Malleus, innervated from cranial nerve #5 (Trigeminal)
- Stapedius
- Stapedius – receives nerves from the 7th (facial nerve)
- Acoustic reflex
- the reflex of the Stapedius to loud sounds
- Eustachian tube
- Connects the middle ear cavity to the nose portion of the throat Almost 36mm, 1.5⬝ in length Has a bony and cartilaginous portion
- Opening situations of Eustachian tube
- It is collapsed all the time, except in 3 conditions, when you pop your ears, when you swallow, when you yawn
- Functions of outer ear
- 1.protect middle and inner ears 2. amplify sounds 3. localize sound source in front/back direction 4. provides info regarding localization of sound source
- maximum amplification of outer ear
- 17 dB at 2500 Hz
- resonant frequency of ear canal
- 2500 Hz
- resonant frequency of concha
- 500 Hz
- three layers of tympanic membrane
- epithelial fibrous mucus
- 2 portions of tympanic membrane
- pars flaccida - (does not have fibrous) pars tensa
- functions of eustachian tube
- equalization of pressure drainage of fluids from middle ear to nasopharynx
- air and fluid mismatch loss of middle ear
- 30 db
- parts of inner ear
- petrous bone carvings (osseus labyrinth) within that, membraneous (gelatinous labyrinth)
- functions of inner ear
- auditory balance
- vestibular portion
- of inner ear 3 semi-circular canals helps maintain balance utricle and saccule
- utricle
- horizontal movements
- saccule
- vertical movements
- cochlea
- the haring portion of the inner ear
- 2 parts of cochlea
- bony membraneous
- % of tumors that are of hearing and balance nerve
- 80%
- turns of cochlea
- basal middle apical
- openings in cochlea
- scala tympani scala vestibuli scala media
- 2 types of fluid in middle ear
- perilymph endolymph
- scala vestibuli has?
- perilymph
- scala tympani has?
- perilymph
- scala media has?
- endolymph
- scala media parts
- organ of corti hair cells diff membranes
- helicotrema
- where scala tympani and scala vestibuli meet
- modiolous
- bony core of cochlea
- basilar membrane
- on the floor of scala media separates scala media from scala tympani
- reissner membrane
- separates scala vestibuli from scala media
- tectorial membrane
- above the hair cells in organ of corti
- inner hair cells
- globular-shaped, like flasks 3 to 4,000 per cochlea, per row afferent
- outer hair cells
- look like cylinders 12 to 16,000 in each cochlea have stereocilia on top 3-4 rows efferent
- active cochlea
- cells inside the cochlea are moving and cause generation of action potential
- tonotopic organization
- the ability to hear high and low frequencies
- cochlea is ____ (wider/narrower) at the base and ____ (wider/narrower)at the apex
- 1. wider 2. narrower
- basilar membrane is ____ (wider/narrower) at the base and ____ (wider/narrower)at the apex
- 1. narrower 2. wider
- We hear ____ frequencies in the base and ____ frequencies in the apex.
- 1. high 2. low
- organ of corti
- discovered by alfonso corti, 19th century cortilymph (very similar to perilymph in chemical compounds)
- times the tympanic membrane is bigger than footplate
- 17
- times the malleus is bigger than the Incus
- 13
- ____ ear is a natural amplifier
- middle. when sound travels into its fluids, evergy is lost, but can make up
- Acoustic neuroma
- Tumor of the 8th cranial nerve (Vestibulocochlear nerve) aka vestibular schwaroma
- inner hair cells mainly attached to ____ nerve fibers
- afferent
- outer hair cells mainly attached to ____ nerve fibers
- efferent
- ___ hair cells have motility
- outer
- Otoacoustic Emissions
- activity from hair cells help us hear soft sounds 2 types: evoked and spontaneous
- evoked OAE
- can be elicited
- spontaenous OAE
- ear can generate by itself 50% females have good SOEA
- when sounds enters cochlea, it creates wave in ___
- basilar membrane
- sounds reach their ____ at the frequency of the ____
- maximum amplitude stimulus
- Central Auditory Pathway
- CAN SUE LOVE IMA Cochlear Nucleus Complex Super Olivary Complex Lateral Lemniscus Inferior Colliculus Medial Geniculate Body Auditory Cortex (Heschl's Gyrus)
- Auditory Brainstem Response
- ABR an electrophysiological recording from the auditory pathways. It is sensitive in detecting hearing thresholds and brainstem dysfunction.
- Von Beckesy
- acoustical (Hungarian) engineer, won Nobel prize in his lab at Harvard. Studied the cochlea of cadavers. Did studies on traveling wave. Now we know a traveling wave by itself is not the reason we can hear. Outer hair cells also play a role.
- passive cochlea
- the response of the cochlea without considering the function of the outer hair cells.
- envelope
- the representation of the maximum movement of the basilar membrane at a certain frequency.
- acoustics
- the science of sounds. A branch of physics. By itself, it has more than 30 different subbranches.
- our range of hearing
- 20Hz to 20,000Hz
- infrasounds
- those frequencies below our hearing The sound of earthquake (infrasound, 5 to 10 Hz).
- ultrasounds
- - those frequencies above our hearing police dog whistles (Galton whistles).
- oscilloscope
- can generate really high frequencies.
- decibels
- A threshold of hearing, represented in intensity
- Intensity depends on the ____ of a wave form.
- amplitude
- medium
- Intensity depends on the amplitude of a wave form.
- elasticity
- The ability of a material that can result in its return to its original shape after displacement.
- chain of collis
- the collision of the molecules of the air which can transfer the energy.
- sound wave
- the movement or propagation of a disturbance (the vibration) through a medium, such as air, without permanent displacement of the particles.
- vibration
- movement or displacement in more than one direction.
- frequency of light
- 50Hz 50 times a second.
- Minimum frequency for cartoons
- 24 Hz
- condensation
- when the density of air molecules increases.
- rarefraction
- the time of the vibration that the density of the air molecule decreases.
- sinusoidal motion
- Simple Harmonic Motion - is defined as a continuous periodic back and forth movement of an object, such as a pendulum.
- cycle
- 1 complete period of condensation and rarefaction.
- period
- the amount of time, in seconds, that it takes to complete one cycle of the vibration. (T)
- frequency
- the number of vibrations completed in one second (F).
- unit
- (Hz) cycles per second.
- Formulas for period and frequency
- T= 1/F and F=1/T (T and F are reciprocal)
- The ____ the period, the ____ the frequency.
- shorter, higher
- pure tone
- a signal made of only one frequency.
- phase
- Another property of sound, of any wave form that deals with time and deals with any stage of a cycle. It is expressed in degrees. If two wave forms start at the same time, degree, position, they are in phase. If not, out of phase.
- Waves can be partially out of phase. (T/F?)
- true
- The amplitude has nothing to do with the frequency or the phase (T/F?)
- True. Amplitude only has to do with movement.
- Two waves with different amplitudes can be in phase. (T/F?)
- true
- amplitude
- magnitude. The amount of vibration in a wave form. It can be expressed in volts.
- peak amplitude
- from the reference (0) to the peak of amplitude (as opposed to peak to peak amplitude)
- Root Mean Square (RMS)
- average amplitude to facilitate comparisons of the amplitudes of different types of sound waves.
- Two waves in phase with different amplitudes
- the one with the greater amplitude may just sound softer (as opposed to canceling out).
- time domain
- (waveform) amplitude variation as a function of time
- frequency domain
- (spectrum) the distribution of the magnitude of frequencies in a sound. Can also be described as: the amplitude variation as a function of frequency.
- The hearing mechanism processes all frequencies as pure tones. (T/F?)
- true
- In basilar membrane, for each of the frequencies that speech has, it amplifies __ frequencies at the apex and __ frequencies at the base of the cochlea.
- low, high
- FM
- Frequency modulation
- Sound is
- an energy, some sort of force or pressure.
- Sound pressure
- Increased and decreased air particles result in high and low pressure.
- Unit of sound pressure
- Pascal (Pa) or dyne/cm2.
- MKS
- Meter, killograms, seconds
- SPL
- Sound Pressure Level - magnitude of sound energy relative to a reference pressure (.0002 dynes/cm2 or 20Mu Pa).
- Pressure
- - (p) force per unit area
- Unit of pressure
- N/m2 or dyne/cm2
- Acoustic Intensity or sound power (I)
- (unit watt/m2 or watt/cm2)
- AI (power) is directly proportional to sound pressure level (p) squared (I p2). (T/F?)
- True
- Minimal Audible Level
- 20MuPa
- 0 dB SPL =
- 20 MuPa
- decibel
- unit of sound pressure It is 1/10 of a Bell
- Formula to convert sound pressure level to decibel:
- 20log10 p1/p2(reference)
- speed of sound
- 330m/sec at ) degrees C
- speed of sound depends on the
- temperature density elasticity of the medium
- the ___ the medium is, the ___ sound travels
- denser, faster
- wavelength
- the separation in distance between successive high-pressure areas
- wavelength is ____ for higher frequencies
- shorter
- smaller frequencies bounce back from our heads (T/F?)
- True
- we use wavelenght to
- study the speed of sound
- each cycle has`
- a positive and negative (compression) and (rarefraction)
- inverse square law
- our sound pressure level decreases with distance. If you double the distance the distance, the SPL decreases by half (in Pascals) or by 6 decibels, and acoustic intensity is 1/4 of the initial value.
- inverse square law made for
- sound-testing environments.
- free field
- environment without reflected sounds
- diffuse field
- sound reflected from many surfaces
- resonance, resonant frequency
- Resonant frequency⬦ the lowest opposition from mass and stiffness of a system. The point where vibration of the air occurs around a sound source without any opposition or lowest amount of opposition.
- a normal adult can hear around how many decibels?
- 10dB
- constructive interference of sound waves
- results in sound waves that have larger amplitudes than original ones. They make themselves stronger.
- destructive interference of sound waves
- results in sound waves that have smaller amplitudes than original ones. They make themselves softer.
- head shadow effect
- is a region of reduced amplitude Those waveforms with longer wavelengths compare to the diameter of the head will have no difficulty passing the head. On the other hand, those waveforms with smaller or shorter wavelengths they cannot pass the head and hence the concept of Head Shadow Effect. This becomes important in people with unilateral hearing loss. Results in difficulty localizing sounds and the cut off frequency is 1000 Hz. Frequencies lower than 1000 Hz, head will not be an obstacle. Higher, yes.
- impedance
- is opposition to the flow of energy. This opposition is a combination is an effect of mass, elasticity, and resistance of a system. Each of these mediums have different impedance (water, sandbox, air).
- middle ear impedance
- if bones moving in fluid, they don’t move as easily.
- admittance
- How easily an energy is admitted by a system.
- immitance
- Combination of impedance and admittance. In the middle ear, we want to know how easily and how hard the energy flows.
- impendance-relate term: stiffness
- opposes low frequency vibration
- impedance-relate term: mass
- opposes high frequency vibration
- absorption
- a feature that talks about how sound can be reduced or absorbed by different materials in an environment. The capacity or ability to absorb sounds in any material is referred to as absorption factor
- Reberveraton time RT60
- This is the amount of time in seconds that it takes for a signal to drop 60 decibels below its original level. (slide) If the reverberation time is too long, by the time they hear a teacher’s sentence, the second sentence is coming in. (Echo?) A room with shorter reverberation time is a good classroom (around 1.2 seconds).
- Fourier analysis
- a mathematical procedure that was developed by Fourier in 1800s (every complex sound in the world is made by many, many pure tones. You can decompose a sound to its original components).
- complex periodic waveform
- Repeats itself every x period of time
- fundamental frequency
- the lowest frequency in Hz that a system can generate. Fsub0. Some Fsub1.
- harmonics
- Multiplications of the fundamental frequency. If 100Hz-200Hz-300Hz. They’re in harmony.
- octave
- when you double frequencies. The first octave of 100Hz is 200Hz. 400Hz. 800Hz. We can hear up to 7 (8?) octaves.
- white noise
- has average amplitude across its frequency range. Approximately from 100 Hz to 6,000 Hz. Used for certain tests.
- speech noise/pink noise/colored noise
- around the frequency spectrum of speech.
- narrow band noise
- A noise concentrated arounda certain frequency. A narrower spectrum around the center frequency (NBN).
- filters
- Low Pass Filter à will only allow low frequencies to pass from it High pass Filter à will allow high frequencies to pass Band Pass Filter à will allow a certain band of frequencies to pass
- duration of a signal
- Shorter duration-- > broader amplitude spectrum Our sentivity to short duration signals is poorer than longer duration signals. If a signal is too short, we cannot perceive it as well.
- transducers
- any device that can convert one form of energy to another form of energy
- microphones
- acousticoelectrical device
- receivers
- electroacoustical device
- sound measurement devices
- Sound level meter à the device that measures intensity and freq of a sound Spectrum analyzer à analyze specturms Oscilloscope à analyze amplitude and frequency (?) of waveforms