Audiology- EXAM 1

audiologist

diagnoses hearing loss, educates about hearing loss/impairment, prescribes and fits amplification devices, provides the latest hearing aid technology, accessorizes the latest hearing technology, programs cochlear implants, diagnoses balance disorders, educates about hearing conservation, and search for cures for hearing loss

medical audiology

employs the largest number of audiologists
-focus: diagnostic assessments to identify cause of hearing and balance disorders

educational audiology

provides identification of kids with hearing loss and referral to proper care, rehabilitation activities, counseling and guidance for parents, students and teachers, selection and evaluation of individual and group amplification

pediatric audiology

provide pediatric testing and empathy to help guide parents and families through a difficult time

dispensing/rehabilitative audiology

dispenses, distributes, sale, and appropriately fit hearing amplification

industrial audiology

design hearing conservation programs, fit hearing protection, monitor employee hearing levels, etc.

tele-audiology

increasing access to audiological services in remote areas

sound

a common type of energy that occurs as a result of pressure waves that emanate from some force being applied to a sound source

requirements for sound

1. source of vibratory energy
2. a medium that has mass and is elastic

intensity

perception of loudness, the higher the magnitude of the compression wave, the higher is the intensity of the signal

pressure level of a sound that is barely audible

approximately 20 upa

pressure level of a sound that is so intense that it is painful

approximately 200,000,000 upa

intensity is measured in

decibels (dB)

Bel

logarithmic unit of measure of sound intensity

frequency

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

the higher the speed of vibration of the compression wave

the higher the frequency of the signal

frequency is usually expressed in

cycles-per-second or Hertz (Hz)

auditory system

outer ear, middle ear, cochlear duct, inner and out hair cells, cranial nerve VIII, auditory brainstem, auditory cortex

inner ear

the innermost part of the ear, containing the cochlea, semicircular canals, and vestibular sacs

osseous labyrinth

the channel in the bone

membranous labyrinth

composed of soft tissue fluid-filled channels within the osseous labyrinth that contain the end-organ structures of the hearing and vestibular systems

the cochlea

the auditory labyrinth and is the sensory organ of hearing
a fluid-filled space within the temporal bone, the shape of a snail shell

outer hair cells

elongated in shape and have small hairs (cilia), attached to their top, three rows, innervated mostly by efferent (motor fibers of the nervous system), about 13,000

inner hair cells

elongated and have an array of cilia on top, single row, cilia in proximity to (but not direct contact with) the tectorial membrane, innervated by mostly afferent (sensory fibers of the nervous system), about 3,500

conductive hearing loss

hearing impairment caused by interference with sound or vibration in the outer ear or middle ear,

sensory/neural hearing loss

hearing loss caused by damage to the inner ear or the auditory nerve

outer ear purpose

conducts sound energy

middle ear purpose

conducts sound energy and increases soudn intensity

inner ear purpose

converts mechanical to hydraulic to electrochemical energy

auditory nerve purpose

transmits electrochemical (nerve) impulses to brain

Schwabach Test

tuning fork test that compares patients BC to normal, placed by the mastoid process

Rinne Test

tuning fork test that compares patients AC to BC, alternate placement between mastoid process and opening to ear canal

Bing Test

tuning fork test used to determine presence or absence of occlusion effect, placement by the mastoid process

Weber Test

tuning fork test used to check lateralization of tone in unilateral losses, placement in the midline of head

audiogram

a tool used to illustrate hearing sensitivity relative to average hearing ability

audiogram depicting normal hearing

lying in 0-10 dB

audiogram depicting a mild to moderate hearing loss

lying from 30-50 dB

audiogram depicting a mild to moderately-severe sensory/neural hearing loss

lying from 20-60 dB

acoustics

the study of the physical properties of sound in the environment

physical characteristics of sound

intensity, frequency, energy, velocity, phase

perceptual characteristics of sound

loudness, pitch, quality/timbre

period (T)

time, in seconds, required to complete one cycle

wavelength

distance, in meters, it takes to complete one cycle
-relationship between frequency and time

sound velocity

speed of sound from the source to another point within the medium
-measured in m/s

speed of sound in air

344 m/s

speed of sound in water

1433 m/s

cycle

a complete vibration consisting of one compression and rare-fraction totaling up to 360 degrees

λ calculation

=c/f

f calculation

=c/λ

beats

the noticeable increase and decrease in sound intensity when two tones of almost identical frequency are presented slightly "out of phase"

complex sounds

vibrations that contain two or more frequencies

oscilloscopes are used to

measure and analyze sound

fourier analysis

the breakdown of a complex wave into its simplest (sinusoidal) components

harmonics/overtones

whole number multiples of the fundamental frequency (F0)

1st harmonic

=fundamental frequency (F0)

2nd harmonic

=F0 x 2 = 1st overtone

3rd harmonic

= F0 x 3 = 2nd overtone

4th harmonic

= F0 x 4 = 3rd overtone

5th harmonic

= F0 x 5 = 4th overtone

speech formants

peaks of energy above the fundamental frequency in vowel sounds, results from altering the shape of the vocal tract

pinna

the cartilaginous portion of the outer ear that collects sound waves from environment and directs them to the ear canal
-aids in sound localization

external auditory canal (EAC)

housed in the temporal bone, the first and second "bends" provide some protection of TM against foreign objects
-slightly curved
-approximately 1 inch in length

outer 1/3 of EAC

cartilaginous, hair follicles, sebaceous glands make earwax

inner 2/3 of EAC

bone

tympanic membrane (TM)

eardrum; a semitransparent membrane that vibrates to transmit sound waves to the ossicles; separates the external auditory canal from the middle ear cavity

quadrants of tympanic membrane

posterior superior, posterior inferior, anterior superior, anterior inferior

artesia of EAC

absence of EAC, could result in conductive hearing loss

stenosis of EAC

narrowing of EAC
-only leads to conductive hearing loss if EAC stenosis leads to closure of canal or if there is blockage of the small EAC by cerumen

microtia/anotia

congenital deformity where the pinna is underdeveloped (microtia) or completely absent (anotia)
anotia-pinna

squamous cell carcinoma of the EAC

considered a tumor
symptoms:
-Ear drainage (otorrhea)
-Ear pain (otalgia)
-Hearing loss
-Facial nerve paralysis

foreign body in EAC

can cause hearing loss if _______ occludes EAC, causes TM rupture, or substantial EAC swelling

external otitis

infection occurring in the skin of EAC, caused by allergic reactions to ear plugs, hearing aid molds, soap, pool water
symptoms:
-ear pain (otalgia)
-ear drainage (otorrhea)
-TM can become inflamed
-itching sensations

otomycosis

fungus in external ear
symptoms:
-otorrhea (ear drainage)
-otalgia (ear pain)
-itching sensations
-conductive hearing loss if fungus accumulation and drainage occludes EAC

air conduction

the process by which sound waves enter the ear through the pinna

bone conduction

occurs as the eardrum vibrates and moves the auditory ossicles

Compression

The part of a longitudinal wave where the particles of the medium are close together.

rarefraction

The part of a longitudinal wave where the particles of the medium are far apart

the decibel

a unit for expressing the ratio between two sound pressures or two sound powers

1 dB is = to how many Bels?

1 dB = 1/10 of a Bel

3 important characteristics of the decibel scale

1. ratio between two numbers (not additive)
2. logarithmic scale
3. decibel levels can be specified with various references

intensity level (dB IL)

decibels can be expressed with intensity references based on output and references levels
dB (IL) = 10 log (IO / IR)

specified referenced for dB IL measurements

10^-12 watt/m^2

output capabilities of speakers are commonly described in

watts

sound pressure level (dB SPL)

intensity is proportional to the square of sound pressure

pressure reference

dB (SPL) = 10 x log (PO^2/ PR^2)

measurement tool for sound pressure level (dB SPL)

sound level meter

Pascals

common unit to used to describe pressure changes in air

Po

pressure observed (measured)

Pr

pressure reference (set references for pressure in air)

atresia of EAC

absence of EAC (canal)

Fourier decomposition

the classical tool for decomposing a given surface or more generally a signal into its basic components, the surface is broken down into different scales using a set of sine and cosine functions with different frequencies.