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Attenuation Decrease in the strength of a sound Schwabach Test Bone conduction test Compares hearing sensitivity of a patient with that of the examiner Tuning fork placed alternately against the mastoid process of the patient and examiner Normal: both stop hearing the tone at the same time. Conductive loss or normal Diminished: patient stops hearing the tone first. Sensorineural hearing loss Prolonged: patient hears for longer. Conductive loss. False normal: caused by cross-hearing Rinne Test Compares sensitivity by AC to BC Louder through AC or BC? Positive: louder by AC. Normal or sensorinueral (same degree of loss in AC and BC) Negative: Louder by BC. Conductive False Negative: cross-hearing (compare AC in TE with BC in NTE, if better can cause false negative) Bing Test based on occlusion effect Tuning fork held to mastoid process while ear canal is alternately open and closed Positive: perceive pulsating sound. Normal and sensorineural Negative: no perceived change in loudness. Conductive Occlusion Effect The impression of increased loudness of a BC tone when the outer ear is tightly covered (occluded) Weber Test Test of lateralization Modified now for use with modern equipment Tuning fork placed on midline of the skull (usually placed on forehead, upper teeth produce loudest sound) Louder sound in which ear? Midline sensation: hear same in both ears. Normal or symmetrical bilateral Lateralized: hear in better ear if unilateral sensorineural. Hear in worse if unilateral conductive (because of prolonged BC) Averts misdiagnosis of unilateral sensorineural loss as conductive when false normal Schwabach and false negative Rinne Strenger Principle when two tones of the same frequency are presented to both ears simultaneously, only the louder one is perceived Elasticity the ability of a mass to return to its natural state. Increases as distance between the molecules decreases (ex: solid is more elastic than liquid) Brownian Motion the rapid and random movement of air particles. Affected by the heat in the environment; more heat more particle velocity Without condensations and rarefractions Transverse wave motion of molecules is perpendicular to the direction of wave motion. Ex: pebble dropped into water Longitudinal waves motion of molecules is along the same axis wave motion. ex: wheat growing in a field Oscillation the back and forth movement of a vibrating body Cosine wave starts at 90 rather than 0 degrees (sine wave) Free vibration the vibration of a mass independent of any external force Damping progressive dimunition in the amplitude of a vibrating body. Critical damping: all vibration ceases before one cycle is completed Forced Vibration the vibration of a mass controlled and maintained by an external impetus Period 1/Frequency Frequency Hz, cycles/second as length decreases, frequency increases as mass increases, frequency decreases as compliance (reciprocal of stiffness) increases, the resonant frequency (f at which the body is most easily made to vibrate) decreases Mass and stiffness have the major effect Stiffness the flexibility or pliancy of a mass Velocity determined by density of the medium V of sound in air is 344 m/s at standard temperature-pressure conditions When temperature and humidity increase, the speed of sound increases Wavelength the distance between the exact same point (in degrees) on two successive cycles of a tone w=v/f (as frequency goes up, wavelength decreases) Phase the relationship in time between 2 or more waves (in degrees) starts at 0 or 360, in phase with the standard Beats periodic variations of the amplitude of a tone when a second tone of slightly different frequency is produced simultaneously. Beats/second is determined by the difference between frequencies Fundamental frequency lowest rate of a sound's vibration Periodic vs Aperiodic sounds Periodic: complex sounds that repeat over time (speech, music) all frequencies are whole number multiples of the fundamental frequency (harmonics) Aperiodic: vary randomly and do not have fundamental frequencies. perceived as noise Harmonics first harmonic is the fundamental frequency, second is twice the fundamental etc The first overtone is equal to the second harmonic etc Fourier Analysis mathematical breakdown if any complex wave into its component parts, simple sinusoids of different frequencies Formant a peak energy in the spectrum of a vowel sound. determined by the individual's vocal tract Intensity how far a body vibrates. The amount of sound energy per unit of area Sine waves may be contrasted by their differences in frequency, intensity, phase Dyne (d) quantifies small changes in force. Force sufficient to accelerate a mass of 1 gram at 1 centimeter per second squared. If a mass of 1 g is held at sea level, the F of gravity on it is 1000 dynes Newton More recent force measurement in the US. 1 N will accelerate 1 kg mass at 1 m/s squared Pressure generated whenever force is distributed over a surface area Normal atm pressure is 105 Pascals If area remains constant, pressure increases as force increases Just audible sound 20 microPa Damaging sound 2x10^8 Pa Work Force x Distance Erg- amount of work done when a 1 dyne force displaces an object by 1 cm 1 Joule=10 million ergs Power rate at which energy is expended Horsepower (746 watts) and watts 1 Watt is 1 mil ergs/second or 10^21 Joules/second Intensity of a sound wave F/unit area - amount of sound energy/unit area Decreases proportionately to the square of the distance from the sound source (Inverse Square Law) decibel (dB) Decibel ratio logarithmic nonlinear may be expressed in terms of various reference levels which must be specified relative unit of measure dB IL 10 x log (Io/Ir) I reference: 10^-12 watt/m^2 Every time intensity increases by a factor of 10, IL increases by 10 dB dB SPL more used in audiology 20 x log (Po/Pr) because intensity is proportional to pressure squared P reference: 20 microPascals (1 microbar=1 dyne/cm^2. Reference is equivalent to .0002 dyne/cm^2) The amplitude of a wave is the same as long as the number of decibels is the same Every time the sound pressure doubles, sound pressure level increases by 6 dB Every time the sound pressure increases by a factor of 10, SPL increases by 20 dB Reference equivalent SPLs American ANSI standard SPL values for normal hearing using supra-aural headphones close to ISO levels dB Sensation level number of decibels above the threshold of a given individual Tone presented at threshold level: 0 dB SL Threshold the level at which the tone can be perceived 50% of the time For audiometry, in a series of ASCENDING trials with a minimum of 3 responses at a single level (don't have to be consecutive) Pitch psychoacoustic correlate of frequency Pitch rises as frequency of vibration rises 20-20000 Hz: range of human hearing Key frequencies for communication between 30 and 3000 Hz Octave: used in music, when f is doubles, raises one octave but raising or a sound 1 octave doesn't double the pitch Intensity contributes to the perception of pitch to a lesser extent Subjective aspect of pitch can be measured in mels. 1000 mels is the pitch of a 100 Hz tone at 40 dB SL Loudness correlate of intensity dB is not a unit of loudness The duration and frequency of sounds contribute to the sensation of loudness Loudness grows faster for low-f tones and certain high f tones Unit: Phon Sone refers to comparison of loudness of a 1000 Hz tone at different intensities. 1 sone is the loudness of 1000 HZ at 40 dB SL Impedance (Z) opposition a medium offers to the transmission of acoustic energy High frequency sounds are attenuated more than low frequency sounds Resonance the ability of a mass to vibrate at a particular frequency with a minimum application of external force Determined by mass, elasticity and frictional characteristics of the medium Reactance the contribution to total acoustic impedance provided by mass, stiffness, and frequency As frequency increases, stiffness reactance decreases Pure tone audiometer each tone is amplified to max of 110 dB HL in the range of 500-4000 Hz with less output above and below those frequencies White Noise (Thermal, Gaussian) broadband/wideband approximately equal energy per cycle, covers broad range of frequencies Earphones limit intensity to 6000 Hz Narrowband Noise focused around specific frequency Critical band provides maximum masking with minimum sound pressure Narrow noise bands on audiometers are usually wider than the critical band Central masking the shift (about 5 dB) in auditory thresholds of a tones produced by a noise in the opposite ear when the level of the noise is not sufficient to cause peripheral masking by cross-conduction Maximum masking threshold of he TE by BC + IA - 5 dB Overmasking masker heard in TE problem when there's a large ABG in both ears Plateau the smaller the ABG the broader the plateau width determined by the AC threshold of the NTE, the BC threshold of the TE, the patient's IA Speech noise obtained by filtering white noise above 1000 Hz at the rate of 12 dB per octave provides more energy in low f spectrum than white noise Audiometer frequencies and intensities 125-8000 Hz, -10-110 dB HL (goes to 110 dB for 500-6000 Hz) 250-4000 Hz: for BC Can't exceed 50 dB at 250 Hz and 70-80 Hz at 500 Hz+ Anechoic chambers rooms in which reverberation is diminished AC Pure-tone audiometry better ear should be tested first, right if not known Preferred testing sequence: 1000,2000, 3000, 4000, 6000, 8000,1000,500,250 Hz etc Testing mid-octave frequencies is recommended when a difference of 20 dB or more is seen in the thresholds of adjacent octaves between 500 and 2000 Hz 3000 and 6000 Hz to turn up notches that may be missed Pure tone initially present at 30 dB HL, if no response increase to 50 dB HL, then increase in 10 dB steps until tone is heard. Then lowered in 10 dB steps until it is no longer heard, then raised in 5 dB steps until it is heard. Then lowered in 10 dB steps and raised in 5 dB steps until the 50% threshold (patient can identify 2 of 3 tone presentations) criteria is met Pure Tone Average (PTA) Average of thresholds at 500, 1000 and 2000 Hz or average of the 2 lowest thresholds obtained at those frequencies Useful for predicting the threshold for speech, gives impression of the degree of communication impact Variable Pure Tone Average (VPTA) the average threshold of the poorest 3 frequencies at 500, 1000, 2000 and 4000 Hz Allows for representation of hearing loss of either flat configuration or isolated primarily within the lower or higher freq range More effective in estimating degree of communication impact of hearing loss Scale of Hearing Impairment VPTA -10 to 15 dB - No comm impact - no hearing aid - no communication training 16-25 - slight - possibly - possibly 26-40 - mild - probably, def for kids - possibly 41-55 - moderate - def- def 56-70 - moderately severe- def- def 71-90 - severe - def - def > 91 - profound- consider cochlear implant - def The space horizonatllly for one octave should be the same as the space vertically for __ 20 dB Distortional BC the response to a sound stimulus evoked when the skull is deformed by a BC vibrator distorting the cochlea and giving rise to electrochemical activity within the cochlea. Vibration distorts bones of skull, distorts cochlea, sets fluids into motion Inertial BC stimulation of the cochlea caused by the lag of the chain of middle-ear bones, or inner ear fluids, when the skull is deformed, resulting in the movement of the stapes in and out of the oval window Osseotympanic BC created when the vibrating skull sets the air in the external ear canal into vibration, causing sound waves to pass down the canal, impinging on the eardrum membrane and being conducted through the middle ear to the cochlea minimize osseo-tympanic and inertial by placing vibrator high on forehead Occlusion effect corrections 30 dB at 250 Hz, 20 at 500, 10 at 1000 Audiometric Weber Test can be performed by using the BC vibrator. Placed at midline of the skull Has been suggested this test be used for determining which ear to mask during BC testing Tactile responses can respond to tactile stimuli in both AC and BC tones primarily in low frequencies when the level are near the maximum out put of the audiometer. When audiograms show severe mixed hearing losses the validity of the test should be questioned (severe sensorineural may be misdiagnosed as mixed) If the vibrator is moved from the forehead to the mastoid and the threshold gets lower, the original response was auditory, if it gets higher, tactile (opposite if the vibrator is moved from the mastoid to the forehead) Bekesy Audiometry automatic audiometry wherein patients track their own auditory thresholds for both pulsed and continuous pure tones by depressing a switch when the tone becomes audible and releasing it when the tone is inaudible. Clinical tool in the differential diagnosis of site of lesion. Observations made of responses to continuous and pulsed tones. Not used today Site of lesion testing in patients with lesions in the cochlea, the loudness growth may be very rapid Loudness Recruitment a large increase in the perceived loudness of a signal produced by relatively small increases in intensity above threshold; symptomatic of hearing losses produced by damage to the cochlea. Tested in unilateral hearing loss by comparing the increase in loudness in the normal ear to the abnormal ear (alternate binaural loudness balance test), Loudness decruitment the less-than-normal growth in loudness of a signal as intensity is increased. Also called subtractive hearing loss, it is suggestive of a loss of nerve units. Retrocochlear site of lesion- no recruitment or decruitment Short increment sensitivity test patients with lesions in the cochlea are able to detect extremely small changes in intensity. SISI designed to test the ability of a patient to detect the presence of a 1 dB increment superimposed on a cotinuous tone presented at 20 dB SL 20 increments- pts with cochlear lesions detect most. Retrocochlear or normal- close to 0% Tone decay loss of audibility of a sound produced when the ear is constantly stimulated by a pure tone. Normal hearing and conductive loss- virtually no tone decay Cochlear lesions- some, up to 20 dB mostly in higher frequencies, above 1000 Hz Retrocochlear lesions on the auditory nerve- dramatic tone decay at all frequencies Volume Units meter used in speech audiometry to visually monitor the intensity of the input source Speech-Detection Threshold (Speech Awareness Threshold) lowest level at which a subject can barely detect the presence of speech and identify it as speech. Sentences preferred over isolated words, cold running speech Speech-Recognition Threshold lowest level at which speech can barely be understood. 50% of spondees correctly identified Preferred test Obtained with the use of spondaic words (spondees)- 2 syllables with equal stress on each, peak at 0 VU SRT is always higher than SDT Can be predicted by finding the of the lowest 2 thresholds at 500, 1000, and 2000 Hz or averaging the thresholds at 500 and 1000 Hz and subtracting 2 dB Can be better than PTA when the audiogram falls steeply at high freqs Can be worse than PTA for elderly patients or ppl with CANS disorders Should be within 5-6 dB of PTA SRT testing with spondees Start at 30 dB HL, if incorrect response increase to 50 dB, if no correct response increase in 10 dB steps until correct response. Lower 10 dB, if correct lower another 10, if incorrect raise 5 dB Continue until patient has repeated 2 out of 3 correct spondees on an ASCENDING trial ASHA recommends a descending procedure that requires testing for the starting level and proceeding with 2 dB or 5 dB steps Most Comfortable Loudness Level usually 40 to 55 dB above threshold Made with continuous discourse (cold running speech) Mostly used in the evaluation of hearing aids Range of comfortable loudness (dynamic range) difference between the threshold and the UCL Normal RCL: 100 dB or more Speech Recognition Score the percentage of correctly identified items on a SRT test Word recognition gets poorer as more high frequencies (above 1900 Hz) are eliminated from speech Phonetically Balanced Word Lists lists of 50 one syllable words that are supposed to contain all the phonetic elements of English speech. These lists are used for testing word recognition. Hirsch's word lists based on Egan's work are called CID Auditory Test W-22, 30 dB SL-most popular Consonant Nucleus Consonant Word Lists phonemically balanced Northwestern University Test No. 6 (yields slightly higher scores than W-22) 40 dB SL- second most popular High-Frequency Emphasis Lists designed to measure the WRS scores of patients with high frequency hearing losses who have difficulty understanding speech Each word contains the /I/ vowel preceded and followed by a voiceless consonant Nonsense Syllable Lists 2 syllable utterance with each syllable produced by a consonant followed by a vowel California Consonant Test designed to be sensitive to the discrimination problems of patients with high frequency hearing losses 100 monosyllabic words are arranged in 2 scramblings, 2 word lists The patient selects from 4 possibilities and marks a score sheet next to the selected word Picture Identification Task CNC words are represented by pictures that are arranged into sets of 4 rhyming words For nonverbal adults Word Intelligibility by Picture Identification series of cards, 6 pictures each. 4 of 6 are possibilities 25 cards in spiral binder and child indicates which picture corresponds to the word they hear For children Northwestern University Children's Perception of Speech (NUCHIPS) Test similar to WIPI Child is presented with a series of 4 picture sets, including 65 items with 50 words scored on the test Synthetic Sentence Identification Test set of 10 synthetic sentences each with 7 words. No meaning. Words from Thordike's list of 1000 most familiar words Competing message of connected speech is presented to increase difficulty Can generate a PI function, steep Central Institute for the Deaf Everyday Sentence Set 50 key words are contained within 10 sets of 10 sentences each Percentage of correctly identified key words determines the score Signal-to-Noise Ratio difference in intensity between the signal and the noise (not an actual ratio) Speech Perception in Noise Test 8 lists of 50 sentences each, only the last word in each sentence is the test item. 200 test words. Test items are recorded on one channel, speech noise on the other elderly patients do not use contextual clues as well as younger patients on this test High probability sentences, can guess last word from context 2 classes, other type- harder to guess last word Quick Speech in Noise Test designed to obtain estimate of a patient's experienced difficulty hearing in noise. Representative of real world 6 sentences presented in the presence of 4-talker babble with 5 key words per sentence Presented at 5 pre-recorded signal to noise rations Score represents a decibel increase in the Signal to noise ratio required by someone with hearing loss to understand speech in noise to someone with normal hearing Commonly used to test effectiveness of hearing aid Connected Speech Test audiovisual (can be audio only) recording with 6-talker speech babble competition 8 sets of 6 passages Patient listens to one sentence at a time and is asked to repeat as much of each sentence as he understands Each passage contains 25 key words Hearing in Noise Test measures listener's ability to hear a sentence in quiet and in noise in the sound field Speech noise is presented at 65 dB HL and the intensity is varied to find hearing level required for 50% of a list of 10 sentences to be repeated correctly Score is given as dB difference between the background noise and sentence level required to attain 50% The higher the SNR, the more difficulty the listener has hearing in noise Performance Intensity Function for PB word lists A graph showing the percentage of correctly identified word-recognition materials as a function of intensity maximum score is obtained at 35-40 dB for normal hearing individuals Highest word score obtainable: PB Max Speech Test Presentation Level minimum of 2 levels 5 to 10 dB above MCL (approximation of maximum performance) Then 90 dB to reveal a possible rollover in performance indicative of retrocochlear disorders Word-Recognition Scores 90-100% - Normal 75-90 - Slight difficulty 60-75 - Moderate difficulty 50-60 - Poor recognition < 50 - Very poor 90-100 excellent word recognition in quiet 80-89 good 70-79 fair 55-69 poor < 54 very poor Audibility Index estimations of a person's speech-recognition ability based on the amount of the speech signal that is audible with a given hearing loss Computed by counting the number od dots below the hearing level plotted on a "count the dot audiogram". The value derived represents the percentage of conversational speech energy audible to the listener with a given hearing impairment at a distance 3 to 6 feet. As AI decreases, perceived hearing handicap increases Should reflect the SRS score for conversational speech intensity (45-50 dB HL) Sound Level Meter An electronic instrument designed to measure the levels of sounds in different acoustic environments Used for calibration Usually incorporates several weighting networks which simulate the 40, 70 and 100 phon equal loudness contours Behavioral Screening Procedure Select a few frequencies: 500, 1000, 2000, 4000 Hz Select fixed cutoff level: usually between 20 and 35 dB HL Present tone frequencies and expect result- if no positive response, fail screening • don't vary intensity • rescreen if they fail initial screening- if they fail again, refer for comprehensive audiological assessment Physiologic test for newborns ASHA guidelines suggest that failure at any frequency in either ear means fail Sensitivity How well does a test diagnose or ID a disorder? The fraction of those with the disorder correctly identified. True Positive/ (True Positive + False Negative) x 100 Specificity How well does a test reject an incorrect diagnosis? The fraction of those without the disorder correctly identified as negative. True Negative/ (True negative + False positive) x 100 Clinical Masking isolates ears from each other using contralateral, direct masking Usually noise tone (noises that are centered around the test tone) Masking efficiency Ratio of obtained masking to the intensity of the noise PBK 50s Kindergarten list for ages 5-7 Open set Redundancy in Hearing Intrinsic-nerve cells extract information from speech signals in nervous system Extrinsic- semantic etc. content embedded in speech sounds Increases as content of speech increases The more redundancy there is in a signal, the more it is immune to the effects of hearing loss Roll-over Excessive roll-over (.45 or more) can indicate retrocochlear site of lesion Roll-over: a decrease in word understanding ability as intensity increases Roll-over ratio: PB min (performance level at a higher level from the one we acquired PB max) (PB max-PB min)/PB max Calibration Frequency Check: not more than 3% variation from the nominal frequency Correction sheets: if the audiometer output is low, the dB of deviation should be subtracted from the measured threshold, added if output is high If the deviation from the required level is 0-2.5 dB - no correction factor needed 2.6-7.5 dB - correction factor of 5 dB 7.6 + - correction factor of 10 dB When to mask and Hood Technique Mask when AC threshold of the TE differs from the BC OR AC threshold of the NTE by over 40 dB Add 10 dB Mask when BC threshold is more than 10 dB (ABG) Add 10 dB and OE value Word Recognition the ability to recognize monosyllabic words presented at a suprathreshold level WRS scores: for 50 words, 100 -(2 x # wrong) for 25, 4 x number wrong History of audiology audiology developed from the professions of otology and speech language pathology Minimum of masters degree for state license ASHA was the first professional home of audiology AAA- American Academy of Audiology