1_2014 basic clinical audiometry

Basic Clinical Audiometry

CSD 451Audiology Section

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)

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.

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).

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.

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).

Types of Hearing Loss

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

Problem with Conducting Sound

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

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

EDIT THIS SLIDE

Types of HL

• Mixed Hearing Loss–Any conductive hearing loss with an

underlying sensorineural component–Combination of conductive and

sensorineural

Types of HL

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

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

Hearing Evaluation

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

• Used to decide appropriate course of action

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)

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

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)

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

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)

Hearing Test

• Measure patient’s audiometric thresholds

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

Air Conduction Testing

• Pure tones presented through the headphones

• Tests the integrity of the entire auditory system

Air Conduction Pathway

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

Bone Conduction Pathway

Finding Thresholds

• Instruct Client

• Response Mode

• Placement of the Transducer

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?)

Audiogram

• Chart of Hearing

• Plot Thresholds

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

Reading the Audiogram

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

• Configuration

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

Degree of Hearing Loss

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

Normal Hearing

X = left earO = right ear

Hearing Loss Simulator

Communicating with the Client

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

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!)