Principles of Audiologic Evaluation SPA 5304

Audiology As a Profession Huh? History Mission Whom do we work with? The Au.D.

Detection and Prevention of ____________ Audiologic ____________________ Referral to : Across the ______________ With patients from various _______________ and _________________ _________________.

Scope of Practice Range of _____________________ Where do you get these? Specializations?

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

First Impressions... Ambassadors of First Impressions? Eye Contact Handshake Honorifics Small Talk? Purpose of Visit

Interview: Open/Closed Questions Neutral/Leading Questions Feedback: –Honest? Hostile? Judging? –Probing? Reassuring? Understanding? – Silent? Nonverbal? How we ask and how we respond sets up expectations on the part of the pt.

Your Social Style: Are you a Driver? Analytic? Amiable? Expressive?

Some Basics Sound, acoustically: vibratory motion of molecules propagated in a medium from a vibrating sound source.

IMPEDANCE The opposition to vibration, or What, other than motion, happens to your applied force? That is what do you have to overcome?

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

Impedance and Frequency: Resistance is generally the same across frequency Reactance Components change with frequency

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

Mass and Stiffness Reactance Resonant Freq.

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

Threshold? Absolute Threshold -- lowest value of stimulus which can be detected Difference Threshold -- smallest detectable change in a stimulus

The Auditory Response Area

Decibels Sound Pressure Level dB SPL = 20 log (Pm/P ref ) Reference Press. = 20 micropascals So, 0 dB SPL = level of a sound with 20 μPa of pressure

Decibels Hearing Level (dB HL) Referenced to average human thresholds in SPL Which depends on: Frequency, and Transducer

SPL to HL Conversions Corresponds to height of curve

DECIBELS A, B, and C scales

Critical Bands: Fletcher

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.

Two Routes to Stimulate Hearing AIR CONDUCTION: Uses both conductive and sensorineural mechanisms BONE CONDUCTION: “Bypasses” conductive mechanism to stimulate sensorineural mechanism directly.

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 ?

Bone Conduction-the Magic and the Myth A bone conducted signal reaches both cochleae 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!

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?

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?

T.F. Test # 3: The Bing Comparing BC with the ear open/occluded Any difference in loudness? Yes ___________________________ No_____________________________

Introduction to Audiometry. Threshold is ARBITRARY: Lindner study: people can percieve qualities of sounds they cannot "hear."

Components of an Audiometer 1. BASIC:

Instructions: Identify listening task –Listening for tones (mostly very soft) –Starting in which ear** Identify response: –Onset –Offset Encourage guessing Ask if any questions

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

THRESHOLD the lowest level in at least half the lowest level at which responses occur in at least half a minimum of three responses of a series of ascending trials with a minimum of three responses required at a single level.

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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Severity of Hearing Impairment Hearing Level (dB HL)Classification -10 to 15Normal 16 to 25Slight 26 to 40Mild 41 to 55Moderate 56 to 70Moderately Severe 71 to 90Severe > 90Profound

Audiometric Configuration Flat< 5 dB avg. diff/octave Gradually Sloping6 to 10 dB/octave Sharply Sloping11-15 dB/octave Precipitously Sloping> 16 dB/octave RisingBetter hrg in high freqs Trough> 20 dB poorer in mid freqs. NotchSharply poorer hrg at one freq.