Gerard RecioKamille SalemZaira RiveraMica Pusing3OTB

To distinguish between the two types of deafness

To know the proper method of performing the Rinne and Weber tests

In doing the experiment there are two tests that we should perform. First is the Rinne test. From our group we chose the representative to whom we would perform the experiment. One ear of the subject was plugged. On the heel of the hand, a tuning fork was set in motion by striking it. At the level of the upper portion of the unplugged ear canal, the stem of the tuning fork was placed on the mastoid processes. When the sound from the vibrating fork disappears, the subject was asked to make a signal. Then, place the line of the fork in front of the unplugged ear at a distance of 3 to 6 inches. Whether the subject hears any sound or not indicate it. The procedure was repeated on the other ear.

For the next test which is the Weber’s test, another member of the group was selected to be the subject. On the heel of the hand, the tuning fork was strike. On the forehead of the subject the stem of the tuning fork was placed. We asked the subject to compare the sounds that was heard in each ear. We indicate whether the sound was heard equally or not.

Outer ear – pinna, external auditory canal

Middle ear – tympanic membrane, three ossicles and the Eustachian tube

Inner ear – cochlea, semicircular canals, nerves

* All three parts are involved in hearing while for vestibular functions, the inner ear is the only one involved.

1. Pinna/auricle/earlobe – funnels the sound waves into the ear

2. External auditory canal – passageway of sound to the middle ear; lined with hair

3. Eardrum/tympanic membrane – transmits sound from the outer ear to the ossicles

4. Malleus, incus, stapes – three small bones of the ear

5. Eustachian tube – equalizes the pressure in the middle ear and the throat

6. Cochlea – organ of hearing; Lt. for “snail shell”; has Organ of Corti

▪ Scala tympani▪ Scala vestibuli▪ Scala media

7.Semicircular canals – three (anterior, lateral, posterior); for balance

8.Vestibule – central part of the bony labyrinth

Malleus faceplate of stapes (3/4 of the amplitude of movement)

Surface area of tympanic mem. : 55 sq. mm.Surface area of stapes: 3.2 sq. mm.

22 TIMES MORE PRESSURE ON THE FLUID.

Reduces the intensity of the sound by as much as 30-40 decibels

Latent period of 40-80 ms Stapedius – pulls stapes outward Tensor tympani muscles – pulls malleus

inward Reduce ossicular conduction Protect cochlea, mask low-frequency

sounds in the env., and dec. sensitivity to own voice

Sound energy Mechanical energy Hydraulic movements Chemical energy Electrical energy BRAIN

Mechanical Energy: Vibrations of the eardrum lever-like action of the ossicles

Hydraulic Energy: Faceplate and oval window Organ of Corti

Scala tympani – perilymph Scala vestibuli – perilymph Scala media – endolymph

Reissner’s membrane (vestibular membrane) – s. vestibuli from s. media

Basilar membrane – s. media from s. tympani; modiolus (high freq. at oval window, low freq. near the apex)

Organ of Corti – contains a series of electromechanichally sensitive cells, hair cells; transduces pressure waves to action potentials

Tympanic membrane>malleus>incus>stapes>oval window>scala vestibuli>scala tympani>basilar membrane>hair cells receptors

Impedance matching-ossicular system reduce distance but increase the force of movement by 1.3X about 22X pressure exerted in the fluid.

The movement of the basilar membrane cause the hair cell stereocilia to bend.

Stereocilia is directionally sensitive:

Upward towards scala vestibuli: hair cells depolarized

Down towards the scala tympani:hair cell hyperpolarized

From the bending of the stereocilia opens ionic channel>influx of K.

Membrane potential decreased to -50mV from 60mV(resting membrane potential)

Opens the Ca2+ channel

Spiral ganglion (cochlear nerve)> dorsal and ventral cochlear nerve (acoustic striae)>superior olivary nucleus> lateral lemniscus>nucleus of lateral lemniscus>inferior colliculus>medial geniculate nucleus>auditory radiation>heschl gyrus brodmann 41,42

1st order neuron: located in SPIRAL GANGLION

2nd order neuron: dorsal and ventral cochlear nuclei[form 3 groups of acoustic striae(lateral lemniscus): ventral striae-most prominent forms trapeziod body]

3rd order: superior olives nucleus 4th order neuron: medial geniculate

nucleus

Area 41 and 42>>Primary auditory area- anterior part: low frequency Posterior part:reception of high

frequency Area 22>>Secondary auditory areaInterpretation of sound and for

association of auditory inputs.

Superior olivary nucleus- fibers joins ipsi and contralateral lateral lemnisci. Localization of sound in space

Nucleus of lateral lamniscus- send axons on both epsi and contralateral lemnisci. Aids in bilateralism by sending axon to the contralateral side.

Whispered Voice TestTicking Watch TestWeber TestRinne TestSchwabach Test

Conductive hearing loss Neural hearing loss (Nerve

deafness) Mixed hearing loss 

sound vibrations don't go from the air around a person to the moving bones of the inner ear

sounds are heard, but they are weak, muffled, and distorted

auditory nerve, which goes from the inner ear to the brain, fails to carry the sound information to the brain

cause a loss of loudness or a loss of clarity in sounds.

Mixed hearing loss combination of conductive and neural hearing losses

Heredity Diseases of the EarInjuries of the Ear

born deafcause is unknownsomething that happened to the

mother during her pregnancy

Ear infections cause fluid or mucus to build up inside the

earfluids drain out of the ear or are absorbed

into the bodyOtosclerosis 

common cause of hearing losshereditary disease in which portions of the

middle ear or inner ear develop growths like bony sponges

can be in the middle ear, the inner ear, or both places

Meningitisinflammation of the membrane(called

the meninges) that surrounds the brain and the spinal column

Punctures of the Eardruma hole in the eardrum, which could be

caused by either injury or disease

Nerve Damageresult of nerve damage is that the

electrical signals of sounds do not get transmitted from the ear to the brain

Loud Noisescommon cause of deafness is repeated

or long-term exposure to loud noisesoften cause moderate to severe hearing

loss.

sound-amplifying devices to aid people who have a hearing

impairment.

Microphone AmplifierReceiver/ SpeakerBattery

picks up sound from the environment

converts it into an electrical signal, which it sends to the amplifier.AMPLIFIER

increases the volume of the sound and sends it to the receiver

changes the electrical signal back into sound and sends it into the ear

those impulses are sent to the brain.

BATTERY

provides power to the hearing aid

designtechnology used to achieve

amplification (i.e., analog vs. digital)special features

Directional microphone T-coil (Telephone switch) Direct audio input Feedback suppression 

help you converse in noisy environments

allows sound coming from a specific direction to be amplified to a greater level

sound coming from in front of you is amplified to a greater level than sound from behind you

allows you to switch from the normal microphone setting to a "T-coil" setting to hear better on the telephone.

Direct audio input allows you to plug in a remote microphone or an FM assistive listening system or connect to other devices

helps suppress squeals when a hearing aid gets too close to the phone or has a loose-fitting earmold

Behind-the-ear (BTE) aids"Mini" BTE (or "on-the-ear") aidsIn-the-ear (ITE) aidsIn-the-canal (ITC) aids and

completely-in-the-canal (CIC) aids

contained in a small plastic case that rests behind the ear

case is connected to an earmold or an earpiece by a piece of clear tubing

often chosen for young children because it can accommodate various earmold types

can help with all types of hearing loss, from mild to profound

Sound travels from the earmold into the ear

fits behind/on the ear, but is smallervery thin, almost invisible tube is

used to connect the aid to the ear canal

allow not only reduced occlusion or "plugged up" sensations in the ear canal

mild hearing loss who can still hear low- and mid-frequency sounds

contained in a shell that fills in the outer part of the ear

mild to severe hearing lossit can accommodate directional

microphones and other added features

contained in tiny cases that fit partly or completely into the ear canal

smallest hearing aids available

In-the-canal (ITC) aidsworks only for mild to moderate hearing

lossusers sometimes experience feedback

noise with this type of hearing aid because the microphone and receiver sit close together

Completely-in-the-canal (CIC)appropriate for mild to moderate

hearing loss, and it's even smaller than the ITC hearing aid

barely visible

Analog hearing aids Digital hearing aids 

aids amplify soundsamplify all sounds equally

Digital hearing aidscontain a computer chipanalyzes the sound based on the person's hearing loss and listening situationadjusts for feedback

Young, P.A., Young,P.H.,&Tolbert,D. (2008). Basic clinical neuroscience. (2 nd ed.). USA:Lippincott Wlliams and Wilkins

Hall, J.E., (2010). Guyton and Hall Textbook of Medical Physiology. (12th ed.).

Ganong,William F.(2006).Review of Medical Physiology 23rd edition.San Francisco,California:Lange Medical Publications

http://health.howstuffworks.com/medicine/modern-technology/hearing-aid3.htm

http://science.jrank.org/pages/3242/Hearing.html

http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/HomeHealthandConsumer/ConsumerProducts/HearingAids/ucm181470.html