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Basic Clinical Audiometry CSD 451 Audiology Section
44

1_2014 Basic Clinical Audiometry

Jul 17, 2016

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Sidorela Doçi

An into to clinical Audiometry
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Page 1: 1_2014 Basic Clinical Audiometry

Basic Clinical Audiometry

CSD 451Audiology Section

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Prevalence of HL in the U.S.

• Hearing loss is the third most prevalent chronic condition affecting seniors.

• 1 in 3 adults over the age of 60 years, and approximately 1 in 2 adults over the age of 75 years have a significant hearing loss.

(AAA, 2005;Gomez, 2005; Kochkin, 2010)

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Prevalence of HL in the U.S.

• Hearing loss is the number one birth defect in the U.S. affecting 3 infants per 1000 births.

• In total, there are over 30 million Americans with hearing loss, approximately 10% of the entire U.S. population.

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Implications of Untreated HL

• Untreated hearing loss has been shown to adversely affect household income by up to $12,000 per year.

• Accounts for a loss of over $18 billion in US taxes collected (Hearing Review, 2006).

• Untreated hearing loss can cause additional costs to Medicare and other health programs due to loss of independence, social isolation, and safety issues in the elderly (Gomez, 2005).

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Implications of Untreated HL

• Children with untreated hearing loss cost schools an additional $420,000.

• Faced with the overall lifetime costs of $1 million in special education, lost wages, and health complications.

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Psychosocial Implications of HL

• Many hearing-impaired people:• become frustrated because of missed

communication • avoid social activities, • spend less time with friends, • have family problems • and feel isolated and depressed.

(National Council on the Aging, 1999).

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Types of Hearing Loss

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Types of HL

• Conductive Hearing Loss– Pathology is localized to the outer and/or the

middle ear– Problem with “conducting” sound to the cochlea– Usually correctable by medical intervention– Accounts for about 10% of incidence of all hearing

loss

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Problem with Conducting Sound

https://www.youtube.com/watch?v=B6wKNEwYs4M

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Types of HL

• Sensorineural Hearing Loss– Pathology is localized to the inner ear or central

system– Not usually correctable by medical intervention– Accounts for 90% of all hearing loss– Most common treatment is hearing aids

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EDIT THIS SLIDE

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Types of HL

• Mixed Hearing Loss–Any conductive hearing loss with an

underlying sensorineural component–Combination of conductive and

sensorineural

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Types of HL

• Central– Brainstem or brain• Central Auditory Processing Disorder (CAPD)

– Wont get into it here, just be aware it exists

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Hearing Evaluation

• Goal is to determine the:– TYPE– CONFIGURATION– SEVERITY – Basic site of lesion

• Used to decide appropriate course of action

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Standard Audiometry

• Basic hearing evaluation:– Case history– Otoscopy– Immitance– Audiometry • Pure tone air and bone conduction• Speech testing

– Counseling• Varies based on patient characteristics (age,

compliance, physical)

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Case History

• “What brings you in today? ”• Different for adults and children• Gives audiologist idea of what to expect– Starting point for testing– Which tests to perform

• Make it a conversation– Try not to read off a list– Let patient lead (if possible)

• Specific questions • Build patient rapport

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Visual Exam./ Otoscopy• Otoscopy

– Clean speculum, make sure it ‘locks’

– Turn on light– Position yourself at ear level – Straighten ear canal– Monitor position– Bridge hand– Monitor insertion – Observe canal, scan TM– Remove speculum;

dispose/clean

• Examine– Pinna– Ear canal– Tympanic membrane

• Otoscope– Battery– Lens– Light source– Specula (different sizes)– (Gloves)

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Immitance• Physiologic tests based on physical properties of the

middle ear system – Looking at the conductive system– Objective (don’t need patient to respond)

• Usually look at admittance (Y) expressed as mmhos– How much energy is allowed to get through

• Measure assumes hard walled cavity but...– Ear canal is NOT a hard walled cavity– We need to create one

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Immitance

• Equipment– Pressure sealing probe with three ports:• Loudspeaker • Microphone• Pressure changing pump

• Probe pushes/pulls TM with ~200 daPA– Stiffens TM, can’t vibrate as well, less energy

reaching inner ear ‘hard walled’ cavity (in theory)

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Hearing Test

• Measure patient’s audiometric thresholds

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Threshold

• What we are measuring/recording with pure tones

• The least intensity required for a patient to perceive an auditory stimulus 50% of the time

• Measured at each frequency that is important for understanding speech– How soft of a sound can the patient hear

• Find for air and bone conduction

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Air Conduction Testing

• Pure tones presented through the headphones

• Tests the integrity of the entire auditory system

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Air Conduction Pathway

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Bone Conduction Testing

• Pure tones are presented through a bone oscillator

• BC testing will bypass outer and middle ear and stimulate the inner ear directly

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Bone Conduction Pathway

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Finding Thresholds

• Instruct Client

• Response Mode

• Placement of the Transducer

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Ascending-Descending Threshold Search(Modified Hughson-Westlake Procedure)

• Start with air conduction, at 1000 Hz, in the BETTER HEARING EAR

• Start at 40 dB, no response increase to 60 dB, no response increase in 10 dB steps until sound is heard– Once they respond, the test has started

• Every time client responds they hear a tone, decrease intensity by 10 dB, if the client does not respond the signal is increased by 5 dB

• Threshold = 2/3 responses at signal level of ascending trials

• Find threshold move on to next frequency– 2000, 4000, 8000, RE-TEST 1000, 500, 250– Can do ascending or descending (what is patient capable of?)

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Audiogram

• Chart of Hearing

• Plot Thresholds

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Audiogram• Symbols

– Uniform across facilities• Right ear information=red

– Air conduction• O-unmasked• -masked

– Bone conduction• < -unmasked• [ -masked

• Left ear information = blue– Air conduction

• X –unmasked• -masked

– Bone conduction• > -unmasked• ] -masked

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Reading the Audiogram

• Unilateral vs. Bilateral• Degree of loss• Type of loss– Sensorineural – Conductive– Mixed

• Configuration

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Using Air & Bone Conduction Information

• If bone conduction responses are better than air conduction responses then the loss is due to a problem with outer / middle ear

• If bone conduction responses are equal to air conduction responses then the loss is due to a problem in the inner ear

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Degree of Hearing Loss

• Terms used to describe the amount of hearing loss a patient has at each frequency

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Normal Hearing

X = left earO = right ear

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Hearing Loss Simulator

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Communicating with the Client

• Ensure the Correct Patient• Building Rapport• Understand the Communicative Partner• Uniqueness of Patients• Barriers to Communication• Special Issues• Time Constraints

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Explaining the Audiogram

• Speak in Lay terms• Explain slowly and clearly • Give examples of how this may be affecting

communication

• BE VERY SENSITIVE TO THE FACT THAT YOU ARE TELLING SOMEONE THAT THEIR OR THEIR CHILD’S HEALTH IS IMPAIRED (and in most cases permanently!)