420 likes | 571 Vues
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 ____________________ Audiologic ____________________ Referral to : Across the ______________
E N D
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 ____________________ • 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.
Driver? Analytic? Amiable? Expressive? Your Social Style: Are you a
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
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
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
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 MAGIC! • 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
Tuning fork tests often useA.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."
1. BASIC: Components of an Audiometer
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 at which responses occur in at least half 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