Audiograms made easy
Pure-tone audiometry– behavioral test measure used to determine hearing sensitivity– test peripheral and central auditory systems– Pure-tone thresholds (PTT’s) indicate:• softest sound audible to an individual at least 50% of the time• plotted on an audiogram bulletAudiogramchart of hearing sensitivityabscissa <=> frequency (range 250-8000 Hz) - represents most of speech spectrum - human ear can detect frequencies from 20-20,000 Hz - children can detect even higher frequenciesordinate <=> intensityIntensity: level of sound power measured in decibels; loudness is the perceptual correlate of intensity.Hearing level (HL): measured in decibels (based on the standardised average of individuals with normal hearing sensitivity)Air Conductionsignal is transmitted through the outer, middle, and inner ear and then through the brain to the cortex.may be performed using headphones, insert earphones, or sound fields.Bone conductionassesses sensitivity when the signal is transmitted through the bones of the skull to the cochlea and then through the auditory pathways of the brain.bypasses the outer and middle ear. Bone-conduction oscillator– small oscillator is placed on mastoid.– stimulates the bones of the skull, which in turn stimulates both cochleaeMaskingMasking presents a constant noise to the nontest ear to prevent crossover from the test ear.The purpose of masking is to prevent the nontest ear from detecting the signal, so only the test ear can respond.Speech Discriminationability to repeat correctly an open set of monosyllabic words at suprathreshold intensity.Word lists are phonetically balanced (PB), ie: the speech sounds used occur with the same frequency as in the whole language. TYPES OF HEARING TESTS
PURE TONE AUDIOMETRY - ADULTS• Hearing is measured with pure tones through headphones• loudness of each tone is reduced until patient can just hear the tone. bullet HEARING TESTS FOR YOUNG CHILDRENBehavioral Observation Audiometry (BOA)- infants < 7 months of age - noisemaker testingVisual Reinforcement Orientation Audiometry (VROA)• children b/w 7 months & 3 years• altering frequency and intensity of sounds, => child's ability to hear sounds across a range of freq’sPlay Audiometry• children > 3 years of age.• child listens to sounds and is taught to make a response every time a sound is heard.Hearing Levels10dB to 20dB = Normal range21dB to 40 dB = Mild hearing loss41 dB to 55 dB = Moderate hearing loss56 dB to 70 dB = Moderately Severe hearing loss71 dB to 90 dB = Severe hearing lossover 90 dB = Profound hearing loss.Conductive hearing loss ("mechanical")blockage or damage to outer +/- middle ear– perforated tympanic membranes– fluid in the middle ear system,– scarring of tympanic membrane.Sensorineural hearing loss ("electrical")damage or malfunction of the:– sensory part (the cochlea) or– neural part (the auditory nerve)congenital or acquiredMixed Hearing Lossproblem in both:conductive pathway (outer or middle ear)nerve pathway (inner ear or nerve)– eg: CHL due to a middle-ear infection combined with a SNHL due to damage associated with agingAbbreviationsCNT - Could not testDNT - Did not testNR - No responseWNL - Within normal limitsAU - Both sides (ears)AS - LeftAD - RightBC - Bone conductionAC - Air conductionPTA - Pure-tone averageHL - Hearing level TympanometryMeasures compliance of middle earNormal (Type A)Hypermobile TM (high peak – Ad)Decreased TM mobility (shallow peak - As)Flat (Type B) – OME or perforation-’ve middle ear pressure (Type C)Other testsOto-acoustic Emission Testing – OAEmeasures function of outer hair cells in the cochleathey respond to sound by producing a very soft sound of their own called oto-acoustic emission.Brainstem Evoked Response Audiometry – BERA (or Auditory Brainstem Response – ABR)provides information on electrical activity generated in response to sound stimulus along nerve pathway, brainstem, and cerebral cortex< 6 months old (may be carried in natural sleep)> 6 months old (under sedation in hospital)
PURE TONE AUDIOMETRY - ADULTS• Hearing is measured with pure tones through headphones• loudness of each tone is reduced until patient can just hear the tone. bullet HEARING TESTS FOR YOUNG CHILDRENBehavioral Observation Audiometry (BOA)- infants < 7 months of age - noisemaker testingVisual Reinforcement Orientation Audiometry (VROA)• children b/w 7 months & 3 years• altering frequency and intensity of sounds, => child's ability to hear sounds across a range of freq’sPlay Audiometry• children > 3 years of age.• child listens to sounds and is taught to make a response every time a sound is heard.Hearing Levels10dB to 20dB = Normal range21dB to 40 dB = Mild hearing loss41 dB to 55 dB = Moderate hearing loss56 dB to 70 dB = Moderately Severe hearing loss71 dB to 90 dB = Severe hearing lossover 90 dB = Profound hearing loss.Conductive hearing loss ("mechanical")blockage or damage to outer +/- middle ear– perforated tympanic membranes– fluid in the middle ear system,– scarring of tympanic membrane.Sensorineural hearing loss ("electrical")damage or malfunction of the:– sensory part (the cochlea) or– neural part (the auditory nerve)congenital or acquiredMixed Hearing Lossproblem in both:conductive pathway (outer or middle ear)nerve pathway (inner ear or nerve)– eg: CHL due to a middle-ear infection combined with a SNHL due to damage associated with agingAbbreviationsCNT - Could not testDNT - Did not testNR - No responseWNL - Within normal limitsAU - Both sides (ears)AS - LeftAD - RightBC - Bone conductionAC - Air conductionPTA - Pure-tone averageHL - Hearing level TympanometryMeasures compliance of middle earNormal (Type A)Hypermobile TM (high peak – Ad)Decreased TM mobility (shallow peak - As)Flat (Type B) – OME or perforation-’ve middle ear pressure (Type C)Other testsOto-acoustic Emission Testing – OAEmeasures function of outer hair cells in the cochleathey respond to sound by producing a very soft sound of their own called oto-acoustic emission.Brainstem Evoked Response Audiometry – BERA (or Auditory Brainstem Response – ABR)provides information on electrical activity generated in response to sound stimulus along nerve pathway, brainstem, and cerebral cortex< 6 months old (may be carried in natural sleep)> 6 months old (under sedation in hospital)
Disclaimer
Please note: The above is intended as a general guideline only for Dr. Becvarovski’s patients.
This material should not be used for purposes of diagnosis or treatment without consulting a physician.
Each patient is an individual and should be treated accordingly.
Please contact our rooms if you are concerned or require any further information.
Please note: The above is intended as a general guideline only for Dr. Becvarovski’s patients.
This material should not be used for purposes of diagnosis or treatment without consulting a physician.
Each patient is an individual and should be treated accordingly.
Please contact our rooms if you are concerned or require any further information.