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TOPIC 4 BEHAVIORAL ASSESSMENT MEASURES The Audiometer Types Clinical Screening The Audiometer Components Pure tone oscillator Attenuator Interrupter switch Output transducer o Headphones • • o Bone conduction vibrators • • o Supra-aural Insert Forehead Mastoid Loudspeakers Audiometer Components Pure Tone Audiometry “The aim of pure tone audiometry is to establish hearing threshold sensitivity across the range of audible frequencies important for communication” The Audiogram Air Conduction vs Bone Conduction Testing Air conduction tests the entire auditory system. Bone conduction bypasses the conductive mechanism, so it tests only the inner ear. Audiometric Symbols Unmasked air conduction Left ear Right ear Unmasked bone conduction Left side Right side Masked air conduction Left ear Right ear Masked bone conduction Left ear Right ear No response What the Audiogram Says About the Impairment Within normal limits Mild Moderate Severe Profound/deaf What the Audiogram Says About the Impairment The configuration of the hearing loss Flat Rising Sloping What the Audiogram Says About the Impairment The degree of hearing loss The configuration of the hearing loss The type of hearing loss Conductive Sensorineural Mixed Establishing a Pure Tone Audiogram o o o o Establish which is the better ear and test first Start air conduction testing at 1000 Hz Begin at 30 dB HL. If there is no response, increase intensity in 20 dB steps until you see a response Follow the “down in 10, up in 5” rule ASHA Procedure Hypothetical threshold search for a listener whose threshold is 35 dB HL. A + indicates the listener heard the presentation, and a - shows the listener didn’t hear the tone. Notice that the hearing level of a trial is raised by 5 dB following a - and is lowered by 10 dB following a +. Establishing a Pure Tone Audiogram o o o o After several crossings of the same intensity, pick threshold as an intensity where 50% of the time the listener responds correctly Move to 2000 Hz, 3000 Hz, 4000 Hz, and 8000 Hz (as a minimum) Pick up the low frequency (500 and 250 Hz) tones Repeat for the other ear Speech Audiometry Uses: Sensitivity for speech Speech awareness threshold Speech reception threshold Pure tone cross check Speech recognition Differential diagnosis Central auditory processing Estimate of communicative function Speech Audiometry Materials Types Nonsense syllables Monosyllabic words Spondaic words Sentence tests Speech Audiometry Relationship of redundancy of informational content and sensitivity to the effects of hearing loss on three types of speech recognition materials Speech Audiometry Intrinsic redundancy Extrinsic redundancy Frequency--low pass filtering Time--time compression Intensity--high presentation levels Competition--speech in noise Binaural--dichotic measures Speech Audiometry Relationship of intrinsic and extrinsic redundancy to speech recognition ability in normal listeners Speech Audiometry Clinical Methods Speech thresholds Speech Reception threshold o o o o o Start audible Present four spondees Calculate percent-correct response Follow down in 10, up in 5 rule Stop at an intensity that provides 50% Speech Audiometry Clinical Methods Speech thresholds Speech Reception threshold Speech Awareness threshold Word recognition testing Word Recognition Testing Things to consider: Materials Goals? Amount of extrinsic redundancy you need? Language level? Other special needs or considerations? Word Recognition Testing Things to consider: Materials Presentation Monaural? Binaural? Headphones? Sound field? Word Recognition Testing Things to consider: Materials Presentation Presentation Level Maximal ability Normal conversational level Speech Audiometry Interpreting speech discrimination results. Typical results based on disorder site Other Behavioral Measures Uses: To determine a functional or exaggerated hearing loss To provide additional information necessary to fit amplification To determine the presence of recruitment and adaptation To determine some measure of binaural integrity