Audiology Midterm

What is sound?

• physical sense: a series of disturbances of molecules within, and propagated through, an elastic medium such as air (sound as vibrations)

• psychological sense: the act of hearing something (sound as sensation)

Sound waves?

• Sound waves transfers energy through air by causing particles to vibrate (kinetic energy), creating changes in density (high and low pressure) and storing/releasing potential energy.

• Wavelength: the time duration to complete one cycle. It has one negative and positive phase.

What unit do we use to measure intensity/amplitude (size or magnitude)?

Unit: Decibel (dB)

• perceptually this is volume

Audiometry typically measures: -10dB to 120dB

What unit do we use to measure frequency (# cycles per second)?

Unit; Hertz (Hz)

• Perceptually this is pitch

Audiometry typically measures: 250Hz to 8000Hz

What does the outer ear consist of?

• pinna

• concha

• external auditory canal

• tympanic membrane

What is the outer ear function?

1. It collects the sound and delivers it to the eardrum (acoustic)

2. Sound waves get to the ear drum and it vibrates (air pressure becomes movement of a physical structure)

• The outer ear collects, localizes, and protects

The pinna funnels the sound towards the canal, the canal modifies the sound pressure before it reaches the tympanic membrane

The order of each ear region performances?

1. outer ear: collects and guides the sound pressure to the tympanic membrane

2. middle ear: transfers vibration through the ossicles to the oval window

3. inner ear: converts fluid motion into frequency-specific neural activity

sound pressure - membrane vibration - ossicular motion - fluid wave - neural signal

What are the middle ear key structures?

• malleus - incus - stapes

• oval and round windows

• middle ear cavity

• auditory (eustachian) tube

What are the 3 middle ear bones (ossicles)?

1. Malleus

2. Incus

3. Stapes

What does the Malleus and Stapes connect?

it connects the Tympanic Membrane to the Cochlea’s Oval window

What does the middle ear do?

• The middle ear transfers sound energy from the air in the outer ear to the fluids of the inner ear.

• The middle ear overcomes the loss of energy that results when sound passes from one medium (air) to another medium (fluid).

Ossicular Chain: The middle ear impedance matcher

The ossicular Chain mechanical movements create amplification to overcome impedance mismatch as the sound waves from the air are transferred to the fluid filled cochlea.

Without the Ossicles, there would be how much hearing loss?

30dB hearing loss

What does the Eustachian tube (middle ear) do?

It equalizes air pressure between the atmosphere and middle ear cavity

What the function of the inner ear?

The function is to transduce the mechanical energy delivered from the middle ear into a form of energy that can be interpreted by the brain.

What are the inner ears structures?

• cochlea

• organ of corti

• hair cells

• cochlear nerve

The inner ear": What an SLP needs to know?

• sound enter the cochlea

• basilar membrane moves (includes the inner and outer hair cells)

• hair cells bend

• transduction

• CN VIII goes to the brain

Which structure equalizes pressure?

auditory tube

Where does transduction occur?

Ossicles

Why do we perform otoscope?

1. IDENTIFY abnormalities

2. OBSERVE if there’s tubes or ear wax

3. ASSIST in ear cleanings

What do we look for while performing an Otoscopy?

1. The ear canal

2. The ear drum

3. Landmarks (Malleus, umbo, cone of light)

Hearing loss: What we must know?

1. bilateral or unilateral

2. symmetric or asymmetric

3. what type in each ear

4. what is the degree

What is air conduction?

Sound that is being conducted through the air.

• Sound waves travel into the outer ear and makes the ear drum vibrate

• This in turn makes the ossicle bones vibrate and sends the vibrations to the cochlea

• the fluid in the cochlea moves through it and up to the auditory nerve which in turn sends it to the brain

What is bone conduction?

A transducer (vibrating speaker) rests against your cheekbone or temple, converting audio signals into gentle vibrations.

• sound vibrates the mastoid bone

• it bypasses the outer and middle ear and goes straight to the inner ear

• the vibrations enter the cochlea via the stapes footplate, which vibrates the cochlear fluid inside

• a neurotransmitter is released which synapses onto the auditory nerve to the brain

Audiogram symbols

What is conductive hearing loss?

Conductive hearing loss happens when sound waves cannot reach your inner ear because of a blockage or damage in your outer or middle ear

What is sensorineural hearing loss?

Sensorineural hearing loss (SNHL) is a common type of permanent hearing loss caused by damage to the inner ear or the nerve pathways leading to the brain.

What is mixed hearing loss?

Mixed hearing loss is a combination of both conductive hearing loss and sensorineural hearing losshappening in the same ear at the same time

• two different parts of your ear are damaged. Sound cannot travel through your outer or middle ear properly, and your inner ear cannot process sound signals correctly

What are potential causes of Conductive hearing loss?

• wax buildup

• fluid in the middle ear

• ear infection

• foreign object

• hole in the eardrum

• Eustachian tube dysfunction

What are potential causes of sensorineural hearing loss?

• noise exposure

• aging

• ototoxic medication

• genetics

• head trauma

• auditory neuropathy

what is unilateral hearing loss?

Hearing is normal on one side of the ear

What is bilateral hearing loss

hearing loss in both ears

What are the PURE TONE AVERAGES?

• 500Hz

• 1000Hz

• 2000Hz

• 4000Hz

What is word recognition testing?

It is the correct percentage using a standardized one syllable word list.

• words are presented at a comfortable listening level

What is an audiogram?

It is a graph to show what a person can hear and what sounds they are missing.

It includes:

• Frequency: pitch HZ

• Intensity: dB

What is the hearing threshold level?

• the SOFTEST tone that is barley audible

What is masking?

A white noise is introduced into the non-test earto ensure the ear we are not testing cannot “cross hear” from the other side

What is normal hearing?

-10 to 25dB HL: adults

-10 to 15 dB HL: kids

What is mild Hearing loss?

• 26 to 40dB HL

Difficulty hearing w/:

• soft voices

• noisy or social places

• consonants and speech clarity

• repetition

Features:

• ear infections

What is moderate hearing loss?

• 41 to 55dB HL

Difficulty hearing w/:

• normal convo will be soft

• they will say they can hear but can’t actually understand

• noise and social places are challenging

Features:

• may speak loudly

• socially disengaged

• Tv volume is loud

What is moderately severe hearing loss?

• 56 to 70dB HL

Difficulty hearing with or without hearing aids

Features:

• speak loudly

• extreme difficulty with social or noisy places

• socially disengaged

What is severe hearing loss?

• 71 to 90 dB HL

Difficulty with: convo level speech is inaudible without hearing aids or implant

Features:

• will likely have difficulty understanding speech

• may be cochlear implant candidate

• may use ASL

What is profound hearing loss?

• 91 to 120dB HL

Difficulty without hearing aids, may not even hear very loud sounds like an airplane engines, traffic, or fire alarms

What is pediatric hearing loss?

• mild to moderate hearing loss

What is the type of HL for Conductive Hearing Loss?

• air-done gap is 15dB or more

• Bone conduction is in normal range but air conduction is abnormal

What is the degree of hearing loss for Conductive HL?

• mild conductive loss

What is the type of Hl for Sensorineural ?

• NO AIR BONE GAP (air and bine symbols are within 10dB of each other)

• BOTH air conduction and bone conduction symbols are abnormal

What is the degree of hearing loss for Sensorineural?

• mild sloping to moderately-severe Sensorineural loss

What type of hearing loss is for Mixed hearing loss?

• air bone gap is 15dB or more

• Bone conduction and air conduction are abnormal

What is the degree of HL for mixed HL?

• moderately-severe to severe mixed loss

what the pathway of sound?

• pinna

• ear canal

• tympanic membrane

• Ossicles

• oval window

• cochlea/haircells

• CN VIII

• auditory cortex

Where does acoustic energy become MECHANICAL energy?

Tympanic membrane begins the mechanical vibration

Where does it become neural activity?

Auditory info travel centrally via CN VIII

Where does it become sensory activity?

cochlear mechanics stimulate the hair cells

Pure Tone Audiometry: Air conduction

• frequenices/pitch tested: 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000 ans 8000 (up to 20,000)

• Amplitude/volume tested: -10dB to 120dB

Pure Tone Audiometry: Bone conduction

• Frequencies/Pitch tested: 500-4000 Hz

• Amplitude/Volume tested: max of 50dB at 500Hz & 70/80dB at 4000Hz

What is SENSITIVITY of a hearing screening event?

% of people with HL who ‘fail’ the screen test

What is SPECIFICITY of a hearing screening event?

% of people with normal hearing who PASS the screening test

what dB starts damage in the inner ear?

85dBA for 8 hours

Behavioral Audiometry; Threshold Searching

1. Familiarization: start at 30dB at 1000Hz for 2-3 secs. If there is no response, go up to 50dB then 60, 70, and more until a response is given

2. Proceed with the down 10, up 5 method

3. only ascending responses count ( 2 out of 3)

4. Record the threshold and move on to the next frequency

TEST ORDER: 1000Hz, 2000Hz, 4000Hz, 8000Hz, 500Hz, 250Hz

What is Tympanometry?

Tests the function of the middle ear by measuring mobility of the tympanic membrane in response to various amounts of positive and negative ear pressure in the ear canal

Meaures how much acoustic energy is let in by the tympanic membrane/middle ear system

• probe tone: 226Hz (adults) and 1000Hz (under 6 months old)

What does the typanogram measure?

• peak pressure: where the eardrum moves most freely (reflects pressure inside middle ear)

• compliance: how easily the eardrum moves (measure middle ear mobility)

• Ear canal volume: air space between probe and eardrum (helps tell perforation from fluid). If someone has perforation, ear canal is LARGER. If fluid present, SMALLER

tympanometry: normative values for kids and adults

Kids: 3-5yrs

• volume: 0.4 - 1.0mL

• Pressure: -99 - 50daPa

• Compliance: 0.2 - 0.9 mL

Adults:

• Volume: 0.6 - 2.5 mL

• Pressure: -150 - 50daPa

• Compliance: 0.3 - 1.4 Ml

Tympanometry interpretation

• Type A: Peak is within normalfor both pressure and height [TYPICAL MIDDLE EAR MOBILITY]

• Type Ad: Peak is within normal limits for pressure BUT shows more compliance than normal [SHALLOW PEAK: STIFFER THAN TYPICAL]

• Type As: Peak is within normal limits for pressure BUT shows less compliance than normal [VERY DEEP/HIGH PEAK: HYPERMOBILE SYSTEM]

• Type B: FLAT with no significant peak [FLUID, PERFORATION OR TUBES]

• Type C: The peak may or may not within normal limits for height BUT is clearly there and is more negative than normal [NEGATIVE EAR PRESSURE]

Tympanometry: When to refer

TYPE B: fluid in middle ear space

What are OAEs (otoacoustic emissions)

are ‘echoes’ produced by the outer hair cells of the cochlea (amplify and sharpen sound)

• echoes measure by a sensitive microphone to ear via a probe

• cochlea sends a tiny sound back to the microphone

What does DPOAE tell us?

• whether or not the outer hair cell produced a response (echo)

• OAEs do NOT determine if the outer hair cell released a neurotransmitter/synapse to the auditory nerve

• it can predict hearing loss (normative date)

• cannot rule out a mild hearing loss

hearing screening skills check

1. infection control

2. check equipment

3. introduce yourself

4. choose probe tip

5. complete tympanometry (identify merger tympanogram type)

6. run OAEs (test in quiet environment. determine whether result is PASS or Refer)

7. Threshold search (obtain threshold at 500, 1000, 2000, and 4000Hz)

8. Explain results