Audiology Exam #1 PDF

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These are all notes from the mandatory to use for the class. The test questions are from the textbook....

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Chapter 4 The Audiometer Audiometer- principal tool used in the process of evaluating a patient’s auditory functioning. -The sounds presented by the audiometer are very specific, and we can be confident the sounds will be consistent. Basic audiometer- make is possible to perform the most fundamental audiological tests, which involves determining how much intensity is needed for a patient to hear pure tones at different frequencies. Pure tone audiometer- must be able to produce pure tones at certain frequencies, precisely control the levels of these tones, and deliver them to the patient in the manner intended by the audiologist. Components of the Audiometer 1.) Power switch- controls the electrical supply to the instrument (with power indicator to show on/off) 2.) Interrupter- (Button) Test tones are presented to the patient by this (allows to turn them off and on) 3.) Frequency Control- used to select among the various frequencies. 4.) Pure tone oscillator- how pure tones are produced. 5.) Stimulus/Tone mode switch- Allows test tone to be presented either continuously on or pulsed on and off at a regular rate. 6.) Warble tone- Frequencies vary periodically rather than staying steady. (not in basic audiometers) 7.) Attenuator/Hearing Level Control (frequency dial, HL dial, attenuator, dial readings) - controls the intensity of the test signal. -Attenuators are calibrated, which means markings on them refer to specific values and increments. -Range of intensities that can be tested are from -10 db HL to 115 db HL for AIR CONDUCTION - ~70 db HL for bone conduction. -Testable range varies for each type of signal. 8.) Output Selector- Direct the signal to the right or left earphone or to the bone conduction vibrator. 9.) Supra-aural earphones- What the standard headset in, earphone/cushion is worn OVER the ear. 1

Insert earphones- pliable earpiece that is inserted into the external auditory canal. Bone conduction vibrator- Held against the mastoid by a spring-like headband.  -Many pure tone audiometers have a second channel that can produce masking noise. (has own interruptor and attenuator) Clinical Audiometers *Vary by manufacturer* - jargon term for a instrument that fits the needs of an audiologist. -Audiometers are usually specified in types by terms of the standards for the functions they provide and the accuracy of these capabilities. -Include features of a pure tone audiometer, plus a wide array of features that enable them to perform sophisticated tests with tones and many other types of signals. -Also include CDS, microphone, inputs for tapes, intercom, etc. Extended high frequency audiometers- test in the 8,000 to 16,000 Hz range. -Output selector of clinical audiometers provides a choice of output transducers such as: 1.) The right or left earphone 2.) Right or left insert receiver 3.) The bone-conduction vibrator 4.) Loudspeakers 5.) Any combination of these Hearing Level -Our actual hearing sensitivity in decibels of sound pressure level (SPL) is not the same at every frequency. Normal Reference Values/ Reference Equivalent Threshold Sound Pressure Levels (RETSPL)- physical intensity needed by normal people to reach the threshold of hearing. -When we say a person has hearing loss- we mean that they require a higher SPL than the norm reference to hear, -Although these reference values have different SPL’s they are the SAME with respect to HEARING. Each of these SLP’s has the same HEARING LEVEL. Hearing Level- Reference has a decibel value of zero. -Each of the threshold values corresponds to a HL of 0 db HL. (Ex: It takes 26.5 db SPL to reach 0 db HL at 250 Hz)

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SPL graph - Read UP

HL- Read DOWN

-Normal person would have straight line with db HL. Audiometer- When the tester sets the attenuator dial on the audiometer it reads in db HL, and the audiometer automatically adds the reference value needed to produce the corresponding physical intensity. Audiometer Calibration National and International Standards- specify the physical characteristics of the sounds that are produced by the audiometer. -Also specify how far the sounds are allowed to deviate from the standard values. -Contained in the ANSI - American National Standard Specifications for Audiometers Calibration - the process of making sure that an instrument is really doing what it is supposed to do. - Audiometer is in compliance with the applicable standards. - When it is calibrated to the ANSI S3.6-2010 standard it is also calibrated to the ANSI/ISO Hearing Level. (INTERNATIONAL STANDARDS plus ANSI standard) Air Conduction Calibration -Calibrated with a sound level meter to ensure the correct SPLs are being presented to the patient. - More sophisticated measurements employ other instruments: Frequency counter- determine whether test frequencies are within acceptable limits. Oscilloscopes and Distortion Analyzers- used to determine the timing characteristics of the test signal and types and amounts of distortions that might be present. AIR CONDUCTION CALIBRATION -Involves measuring the sounds produced by the earphones and is done separately for each earphone. NBS-9A Coupler- what the earphone is placed on, a metal cavity having a volume of 6 cc. It is used because it approximates the acoustical characteristics of an ear. (also called 6-CC COUPLER OR ARTIFICIAL EAR)

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-The microphone at the bottom of the coupler is connected to the audiometer calibrator or sound level meter, and measures the actual SPL being produced by the earphone. Sound level calibrator- measures the accuracy of the sound level meter. 2cc Couplers or Occluded Ear Simulators - help obtain reference values for insert earphones. -Done because insert receivers are placed into the ear canal, instead of over the ear. -Extended high frequency audiometry involves testing patients with high frequencies, and requires the use of special insert receivers or circumaural earphones. -Outputs of insert receivers are tested with an occluded ear simulator, because the shape a flat plate adaptor allows the circumaural earphone to couple the artificial ear. How to Perform a Sound Level Calibration (once you know reference SPLS): 1.) 2.) 3.) 4.) 5.) 6.)

Select frequency Set attenuator to a convenient level. (around 70 dB) Turn on tone Read the meter on calibrator to measure the actual SPL that is produced by the earphone. Compare the actual SPL to what it's supposed to be Record differences

-Calibration worksheet allows you to record differences. -An audiometer is out of calibration if it deviates from the reference values in the standard by an amount that exceeds the allowable tolerances. 3 ways to handle this: 1- Internal settings need to be adjusted 2- Instrument may need to be repaired 3- A correction chart can be posted, to show how to adjust test results -

Hearing level dial/ attenuator needs to be calibrated for linearity. Done by changing the attenuator setting throughout its entire range to make sure that every 5dB dial change results in a 5dB change in SPL on the earphone. Needs to be within + or - 1 dB per 5 dB step.

-Frequency calibration is required to ensure each test frequency is within a certain percentage of the nominal value. -Must be within - or + 1 and - or + 2 depending on the audiometer type. TYPE 1 AND 2 AND HIGH FREQUENCY --- 1% 2% FOR TYPE 3 AND 4 4

-Ex: if dial set at 1000 HZ must be between 990 HZ and 1010 HZ for type 1 and 2. -Other calibrations needed are done by technicians. BIOLOGICAL CALIBRATIONS -Checking the thresholds of someone whose hearing levels are already known. -Also should have a general listening check to see if machine is working well. BONE-CONDUCTION CALIBRATION -Can be done using an ARTIFICIAL MASTOID or MECHANICAL COUPLER -Usually done by a service technician. -Almost the same as air conduction calibrators, just using threshold for bone conduction. Reference Equivalent Threshold Force Levels )RETFLs - show the force needed to achieve 0 db HL with bone conduction stimulation, so used for calibration. -Biological Bone Conduction- based on the premise that bone and air conduction are the same in patients with sensorineural hearing loss. Use these patients with this hearing loss to conduct a test of each frequency that bone conduction testing is done. (Read this over page 98) Calibrating the Speech Signal -Most audiological procedures use various kinds of speech stimuli. -Can be monitored voice or live voice. -Both involve using the audio meters VU or Monitoring Meter, to tell whether the level of the incoming signal is appropriate. -Want the VU to fall in 0dB measurement. -In LIVE VOICE- Audiologist talks into the microphone while monitoring her speech on the VU meter to have average speech reach 0 dB. Monitored Live Voice (MLV) - Presents speech in the LIVE voice that is calibrated. Recorded Speech Tests- usually have a 1000 Hz calibration tone on the recording. (average level of speech peaks) RETSPL for speech is 12.5 dB higher than the RETSPL for 1000 HZ tone. -The calibration procedure uses the recorded calibration tone the same way as pure tone, except the selectors are set for speech and the reference level is now 20 dB HL. Sound Field Calibration -Sound field testing means the sounds are delivered to the test room by loudspeakers instead of through earphones. 5

-The signal from the loudspeaker is transmitted through the air and picked up by the microphone of the sound level meter, which is placed where the patient's head would be. -Different standards for monaural and binaural listening when the loudspeaker is located directly in front of the patient.

TEST ENVIRONMENT AND AMBIENT NOISE Masking- One sound interferes with the ability to hear other sounds. -Must make sure audiological testing is done in a room quiet enough so that the softest test sounds used will not be masked by any noise in the room. (Ambient noises must be low enough to test 0 dB. )

Audiological Testing Rooms -To meet the need for an appropriately quiet environment, audiological testing is performed in specially constructed, sound-isolated rooms. (Can be purchased) -Commercial audiometric booths (can be generalized for others)- come as either single rooms or two room suites. One room- Patient stays in booth and tester and equipment are outside. Two room- Patient in one room and then a control room. -Both rooms should be as quiet as possible. -Patient room should be as large as possible and testers room should be large enough to accommodate tester and equipment. -Must also account for room doors, wheelchair access, and test suite. -Walls, ceilings, floors, and doors must be constructed of 4 inch thick panels composed of metal sheets filled with sound attenuating material and covered with holes. -Type of room construction is dictated by the amount of sound attenuation that is needed in light of the noise levels at the location in question. (Read rest of it for more, pg 103)

Maximum Permissible Ambient Noise Levels

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Ambient noise in the audiometric booth is measured with a sound level meter, it is important to know how much noise exists in the vicinity of each audiometric testing frequency. We must specify a range of frequencies to be considered around each frequency. This can be done in terms of octave bands (1 octave wide) and third octave bands (⅓ of an octave wide). Bandwidth - the range of frequencies between the lower and upper cutoffs. Bandwidths are used when specifying the maximum allowable room noise levels for each audiometric frequency. In order to be sufficiently quiet for audiological testing, ambient noise levels in the room are measured with a sound level meter that has a set of octave-band or ⅓ octave band filters. The sound pressure level within an octave band is called a octave band level. Sound pressure level with a third octave band is called a third octave band level. These ambient noise levels are then compared with the maximum permissible ambient noise levels. Two sets of maximum octave band levels are given for each frequency - one with ears covered and one with ears uncovered. Higher noise levels are allowed with earphones because they help reduce amount of sounds reaching the eardrum. Ears uncovered ambient noise standards must be met by all rooms where bone and sound field testing is done. Ears covered is used in air conduction. Higher noise levels become acceptable at low frequencies when the range of frequencies being tested changed from 125-8000 HZ, 250-8000 HZ, or 500 to 8000 HZ. Using maximum noise levels for 250 to 8000 is no problem because: 1.) most clinical testing is limited to this 250-8000 Hz range 2.) Patients who need to be tested at 125 Hz usually have hearing losses that are so severe ambient noise isnt an issue. Ambient noise is a limiting factor and when testing air and bone conduction must meet both standards because can distort comparison. Study: Frank and Williams studied noise levels of 136 rooms in a variety of different types of audiological facilities. Only 14% of the rooms met the standards for ears uncovered for either 125 to 8000 or 250 to 8000 37% of the rooms met the standards for testing at 500 to 8000. 50% for testing either 125 to 8000 or 250 to 8000 82% for 500 to 8000 It is necessary to do hearing screening tests in schools in quiet rooms.

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Goal is to see who is probably normal at 25dB at different frequencies and who needs further evaluation. The ambient noise levels in the room are as much as a limiting factor for screening tests as they are for clinical tests (must be taken into consideration).

Chapter 5 Hearing Threshold -We can quantify the degree of a patient’s hearing loss in terms of the magnitude of the stimulus needed for him to respond to it. Threshold- smallest intensity of a sound that a person needs to detect its presence. Clinical purposes: threshold is the lowest intensity at which a patient responds to a sound at least 50% of the time. -Test sounds need to be clearly specified, and are usually pure tones. -Hearing thresholds given in db HL. -Normal threshold = close to the norm -Hearing loss = tones must be presented at higher intensities for them to be heard. (how many decibels above 0 db HL are needed to reach threshold. -Test signals can be presented by both AIR CONDUCTION or BONE CONDUCTION or IN THE SOUND FIELD. -Thresholds are obtained for BOTH air and bone conduction because comparison allows us to distinguish between the different types of hearing loss. AIR CONDUCTION TESTING -Presenting test signals from earphones or insert earphones. (standard earphones more convenient). -Anything to interfere with testing should be removed (jewelry, headbands) -Hearing aids should be removed and remove gum or candy. -Check if there is anything putting pressure on the external ear that can cause the ear canal to close and give a false impression of conductive hearing loss. -CLINICIAN should then put the earphones on over the entrance to the ear canal. BONE CONDUCTION TESTING 8

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Applying a vibratory stimulus to the skull, which is transmitted to the cochlea and heard as a sound. Bone conduction vibrator- placed on the mastoid process or forehead and is held in place by a head band. (MASTOID RECOMMENDED) Vibrator is in a small plastic shell and a disk comes in contact with the skin. B71 and B72 used. Must assess any structural or other problems that would affect proper placement. (hair, oily skin, mastoid oddly shaped) Also pathology and surgically modified structures are important to look for. Earrings, gum, etc. should also be removed. Vibrator is placed on the mastoid process on one side and the spring band is on the other side. (anterior) Vibrator should be placed so the disk sits flat on the skin of the mastoid and doesn't touch the pinna. Vibrator is kept in the location where the tones sound the loudest because placement differentiations can result in threshold differences. Patient should keep head still and not talk during testing and say if vibrator moves. Present a strain relief so that a tug won’t dislodge the vibrator.

OCCLUSION EFFECT Unoccluded bone conduction thresholds- when the ears are not covered by earphones while bone conduction is being tested. Occluded bone conduction thresholds- One or both ear are covered with earphones. -Stronger signal reaches the cochlea with occluded than unoccluded This boost in signal is called the occlusion effect. -Occlusion thresholds holds are lower (better) than unoccluded. -Occlusion occurs when cartilaginous section is occluded not when bony portion is blocked/ disorder of conductive system. -Can help determine whether a conduction impairment is present in the form of the Bing test and to determine how much noise is needed for masking during bone conduction. -Occlusion effect found by comparing unoccluded and occluded thresholds. -Occlusion effect occurs for frequencies up to ~1000 Hz, and largest at lower frequencies. VARIES AMONG PEOPLE.

Mastoid vs. Forehead Bone Conduction

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-Forehead testing - Higher retest reliability and lower intersubject variability. (too small benefits to have clinical significance) ADVANTAGES OF FOREHEAD -

Mastoid vibrators can shift easily, while forehead placement is very stable. The middle ear component makes a bigger contribution to the normal bone-conduction threshold with mastoid placement than with forehead placement. Conductive pathologies have a bigger effect on bone-conduction thresholds with mastoid placement than with forehead placement. (want to test cochlea directly)

MASTOID ADVANTAGES -Advantages are of clinical importance. - Strength of the vibration needed to reach threshold is smaller when the vibrator is on the mastoid than when it is on the forehead. -Takes less vibratory energy to reach threshold at the mastoid than on the forehead. -Wider range of bone conduction thresholds can be tested at the mastoid. -Bone conduction has a wider dynamic range at the mastoid than the forehead. -No interaural attenuation for bone conduction so the signal reaches both cochlea directly. -The interaural attenuation for mastoid bone conduction is an advantage for mastoid placement because it can avert the need for unnecessary masking under some conditions. -Some audiologists test forehead bone conduction while the patient is wearing an air conduction headset, called “forehead occluded bone conduction” - The dynamic range problem that comes with placing the vibrator at the forehead can be overcome by a boost in the bone signal that comes from covering the ears, however, this is too variable.

PRETESTING ISSUES/CONSIDERATIONS Talk Before You Test -Want to establish a working rapport with patient. -Also want to review or talk about patient's case history and ask about any changes since last visit.

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-Observe patient to develop a picture of his auditory status, communicative strategies and related behaviors. -Information during the interview will be combine with the formal test to reach a clinical audiologic impression and will help plan patients aural rehabilitation. -Also will be useful when giving instructions and making other decisions about how to test. Look Before You Touch -

See if there are any apparent structural abnormalities and asymmetries of the head and ears. Perform an otoscopic inspection prior to testing. Helps lead to appropriate referrals and may affect how testing is done/interpreted.

Orientation of the Patient -The patient should be seated comfortably, preferably with armrests. -Chairs that swivel or lean back should be avoided. -Many audiologists prefer that the patient is seated with her back to the clinician because they might receive clues that come from: 1.) The tester’s behavior 2.) The reflection of the indicator lamp on the audiometer. -Others believe that the patient should face the clinician because: 1.) Patient behaviors that affect test outcomes can be observed. 2.) Many...