Hearing Problems - Test 1

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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 â€“ 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 donâ€™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 teacherâ€™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. Theyâ€™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

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