1-5304-intro

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Principles of AudiologicEvaluation

SPA 5304

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• Detection and Prevention of ____________

• Audiologic ____________________

• Audiologic ____________________

• Referral to:

• Across the ______________

• With patients from various _______________

and _________________ _________________.

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Scope of Practice

• Range of _____________________

• Where do you get these?

• Specializations?

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Client? Patient? What do I call you?

Does that affect what I think of you?

How do I treat you?

• With R-E-S-P-E-C-T

• With Positive Regard

• With Congruence

• With Empathy

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First Impressions...

• Ambassadors of First Impressions?

• Eye Contact

• Handshake• Honorifics

• Small Talk?

• Purpose of Visit

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Interview:

• Open/Closed Questions• Neutral/Leading Questions

• Feedback:

– Honest? Hostile? Judging?

– Probing? Reassuring? Understanding?

– Silent? Nonverbal?

• How we ask and how we respond sets upexpectations on the part of the pt.

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Your Social Style:

Are you a• Driver?

• Analytic?

• Amiable?

• Expressive?

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Some Basics

Sound, acoustically:

vibratory motion of molecules propagated in a medium from a

vibrating sound source.

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IMPEDANCE

• The opposition to vibration, or

• What, other than motion, happens to your

applied force?

• That is what do you have to overcome?

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Impedance has 3 components:

• Resistance: Energy lost to heat through friction

• Mass Reactance: Energy taken to overcome

inertia

• Stiffness Reactance: Energy taken to overcome

restoring force

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Impedance and Frequency:

• Resistance is generally the same across frequency

• Reactance Components change with frequency

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Reactance and Frequency:

• Mass reactance is greater at high frequencies

--it’s harder to get massive objects to vibrate

quickly

• Stiffness reactance is greater at low frequencies

--it’s harder to get stiff objects to vibrate slowly

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Mass and Stiffness Reactance

0

0.2

0.4

0.6

0.8

1

1.2

100 500 1000 4000

Frequency

R e a c t a n c e

Xm

Xs R e s o n

a n t F r e q .

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At Resonant Frequency

• Mass and Stiffness Reactance Cancel

• Only opposition to vibration is Resistance

• In Forced Vibration, you get the most

vibratory amplitude for amount of force

applied

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Threshold?

• Absolute Threshold -- lowest value of

stimulus which can be detected

• Difference Threshold -- smallest detectable

change in a stimulus

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The Auditory Response Area

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Decibels Sound Pressure Level

• dB SPL = 20 log (Pm/Pref )

• Reference Press. = 20 micropascals

• So,

• 0 dB SPL = level of a sound with 20

μPa of pressure

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Decibels Hearing Level (dB HL)

• Referenced to average human

thresholds in SPL

Which depends on:

• Frequency, and

• Transducer

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SPL to HL Conversions

Corresponds to

height of curve

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DECIBELS A, B, and C scales

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Critical Bands: Fletcher

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A Basic View of Hearing & Hearing

Loss

• The Hearing Pathway can be divided into two

major divisions:

– CONDUCTIVE

– SENSORINEURAL

• Outer & Middle Ear = Conductive Mechanism

• Inner Ear &Aud Nerv. Sys = Sensorineural Mech.

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Two Routes to Stimulate Hearing

• AIR CONDUCTION: Uses both

conductive and sensorineural mechanisms

• BONE CONDUCTION: “Bypasses”

conductive mechanism to stimulate

sensorineural mechanism directly.

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Hearing Loss, A.C. and B.C.

• Sensorineural Pathway is disordered:

– HL is seen in both AC and BC

• Conductive Pathway is disordered:

– HL only via ?

C d i h i d

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Bone Conduction-the Magic and

the Myth

• A bone conducted signal reaches bothcochleae equally

• No matter where you place it!

• Bone Conduction doesn’t use conductive

mechanism• The truth is it actually does depend on the

outer and middle ear to some extent.

Myth

MAGIC!

T i f k f

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Tuning fork tests often use

A.C. and B.C.

• E.G., the Rinne, in which you compare

hearing by AC to that by BC.

• What should happen:

• If there is a sensorineural hearing loss?• If there is a conductive loss?

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Tuning Fork Test #2:The Weber

• Via BC at midline.

• Can you hear this? If so, where?

• Louder in RE?//Equal?//Louder in LE?

• What should happen?

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T.F. Test # 3: The Bing

• Comparing BC with the ear open/occluded

• Any difference in loudness?

• Yes ___________________________

• No_____________________________

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Introduction to Audiometry.

• Threshold is ARBITRARY:

• Lindner study: people can percieve

qualities of sounds they cannot

"hear."

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Components of an Audiometer

1. BASIC:

F r e q u e n c

O s c i l l aG e n e r a t e

A m p l i f I n c r e a s e

L e v e l C o

A t t e n uC o n t r o l s

S w i t c h

G a t eT u r n s t o n

T r a n s dE a r p h o n e

B o n e V i b

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Instructions:

• Identify listening task – Listening for tones (mostly very soft)

– Starting in which ear**

• Identify response:

– Onset

– Offset• Encourage guessing

• Ask if any questions

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Modified Hughson-Westlake

• Ascending Procedure

• Adaptive

• Raising level in 5 dB steps

– With each failure to respond

• Reducing level in 10 dB steps

– With each response to the signal

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THRESHOLD

the lowest levelthe lowest level at which responses occur

in at least half in at least half

of a series of ascending trials with aa

minimum of three responsesminimum of three responses

required at a single level.

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THE AUDIOMETRIC

FREQUENCIES• The octaves from 250 to 8000 Hz. Why?

• Speech perception.

• Inter-octaves (750, 1500, 3000, 6000 Hz)

– required when thresholds at the adjacent octaves

differ by 20 dB or more

• Above 8000 Hz = “Ultra-audiometric”

– Used in tracking ototoxicity

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^

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Severity of Hearing Impairment

Hearing Level (dB HL) Classification

-10 to 15 Normal

16 to 25 Slight26 to 40 Mild

41 to 55 Moderate

56 to 70 Moderately Severe

71 to 90 Severe

> 90 Profound

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Audiometric Configuration

Flat < 5 dB avg. diff/octave

Gradually Sloping 6 to 10 dB/octave

Sharply Sloping 11-15 dB/octave

Precipitously Sloping > 16 dB/octave

Rising Better hrg in high freqs

Trough > 20 dB poorer in midfreqs.

Notch Sharply poorer hrg at one

freq.

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Documents

1-5304-intro