• ASHA gives the following values for quantifying the severity of the hearing loss (all in dB HL)
• Normal = -10 to 15
• Slight = 16 to 25
• Mild = 26 to 40
• Moderate = 41 to 55
• Moderately Severe = 56 to 70
• Severe = 70 to 90
• Profound = greater than 90

• We always describe the audiogram from left to right
• We always describe the audiogram in terms of severity
• We generally only label with the hearing loss
• We DONT say "A normal to severe hearing loss" we DONT usually describe "normal" hearing

Hearing Loss Descriptor Phrases

**KNOW THIS**

• "Mild to moderate"
• "Moderate to profound"
• "mild high frequency hearing loss"
• "severe high frequency hearing loss"
• "reverse slope audiogram rising from severe to mild"

• Sensorineural HL: Formerly called perceptive loss or nerve loss, this term refers to loss of hearing sensitivity produced by damage or alteration of the sensory mechanism of the cochlea or the neural structures that lie beyond.
• Conductive HL: The loss of sound sensitivity produced by abnormalities of the outer ear and/or middle ear.
• Mixed HL:  A sensory/neural hearing loss with superimposed conductive hearing loss. The air conduction level shows the entire loss; the bone-conduction level, the sensory/neural portion; and the air-bone gap, the conductive portion.

• After obtaining air conduction thresholds, we re-test thresholds using bone oscillator
• Bone conduction helps to stimulate the cochlea to know if the hearing loss is conductive or sensorineural
• The bone oscillator is attched to a snug-fitting headband and is placed over the patients head.
• The oscillator sits on the mastoid process
• With the bone oscillator placed here, we are actually "shaking the skull" to make the cochlear fluid move.
• We interpret this as sound
• We repeat the audiogram at the following frequencies: 500 Hz, 1k Hz, 2k Hz & 4k Hz

• If the patient hears better through bone conduction than through air conduction, then we know the patient has a conductive hearing loss.
• If the patient's hearing through bone conduction is the SAME as through air conduction we know that the loss is sensorineural.

• There are limitations to how much intestity we can use before the possibility of involving the ear we do NOT want to test.
• Masking is a way of "keeping the contralateral ear busy" (aka the non testing ear)
• If they have a "normal" right ear and the left ear has a severe hearing loss, we might need to mask.
• Whe we reach higher intensities, we run the risk of some of the sound "spilling" over into the non-test ear (in this case the better ear)

• If the difference between the two ears (AC) is 40 dB HL or more, we need to MASK. (Also used for IA for headphones.)
• Masking has to occur because after 40 dB HL some of the sound can cross over to the opposite ear.

Concern for getting correct threshold

(one of the reasons why masking is used)

• Medicaid qualification.. the difference between correct and incorrect can mean the difference between whether or not an indigent patient receives hearing aids
• Worker's compensation
• Legal cases
• Hearing aid fitting
• Competence.. others will see your work.

• Right ear unmasked = CIRCLE
• Right ear masked = TRIANGLE
  
• Left ear unmasked = X
• Left ear masked = SQUARE
  

• Right ear unmasked = <
• Right ear masked = [
• Left ear unmasked - >
• Left ear masked = ]
  

• 40 Db is considered the "interaural attenuation" rate
• Interaural Attenuation: "As sounds travel from one side of the head to the other, a certain amount of energy is lost in transmission. This loss of intensity of a sound introduced to one ear and heard by the other is called interaural attenuation."
• Another way to define it is, " The dB HL level above which sound can cross from one side of the heat to the other when testing hearing sensitivity."

Masking Intensity Levels

**KNOW THIS**

• Supra-aural headphones 40 dB
• Insert ear-phones 70 dB
• Bone conduction 0 dB

• Less frequent need to mask
• Quicker testing
• Less fatiguing to the patient
• Most audiologist use this as much as possible

• Unilateral Conductive HL
• Bilateral Conductive HL
• Unilateral SNHL (differing by more than IA)

• The difference between the 2 ears thresholds has to be 40 dB HL

• Hearing WNL bilaterally
• Bilateral symmetrical SNHL

1. Broadband noise: (aka white noise) (like when your radio can't find a station)
2. Pink Noise: aka "speech weighted noise"
3. Narrow-band noise (NBN): It uses less spectral energy (it's not a broad response like white noise). It's most effective for masking. You can use lower intensity and get more masking effect than white noise.

• Because the fluid in both cochlea shake

Speech Reception Thresholds

** KNOW THIS**

• Sometimes called Speech Reception Threshold, sometimes called Speech Recognition Threshold.
• Both terms are acceptable
• SRT's are used promarily as a cross-check test
• We test them using the same methods used for obtaining pure-tone thresholds
• down 10, up 5

• Use spondee words to test SRT
• Spondee words are compound words that have
• Equal emphasis on each syllable
• Each syllable has an equal duration
• Sample words:
• hotdog
• baseball
• ice cream
• airplane

• Words can be presented in two ways:
• Monitored Live Voice
• Recorded speech (typically on CD these days)
• Best method is to use recorded speech as the CD player can be calibrated to the audiometer so that speech is always presented in the correct way.
• First thing that should be done before beginning testing is to familiarize the subject with the word list you will be using. (10 to 15 different spondees)
• If you don't familiarize the subject, the test is actually invalid
• Want to present the first word at an audible level
• If you have completed pure-tone testin, you can add 20 dB to the pure tone average as a starting point
• Pure tone average = the average of 500, 1000, and 2000 Hz (add them up and divide by 3)
• Many audiologists will obtain SRT prior to pure-tone testing for cross check purposes

• When presenting stimuli for SRT (spondee words) you need to monitor the VU meter on the audiometer
• VU stands for "volume unit"
• The object is to keep the VU meter centered at zero during presentation
• If you "overshoot" or "undershoot" zero, you are not actually presenting at the level set on the audiometer
• Then you will not obtain a true SRT for the patient

• SRT should always be +/- 7 dB from PTA

• If you know that the SRT and PTA do not march, there is a possibility that the patient is malingering

MCL & UCL

• Most Comfortable Level (MCL): falls somewhere between Threshold and UCL-- usually close to 40 dB SL
• Uncomfortable level (UCL)

• Range of comfortable loudness
• arithmetic difference between a threshold measure and the UCL (UCL minus SRT)
• Also known as Dynamic Range (DR)
• Used to fit hearing aids and used for other rehabilitative measures

• Measure of discrimination, or ability to understand speech
• Also used as a screening tool for vestibular schwannoma (tumors)
• WDS is not a threshold measure as SRT is
• WDS presentation is typically at higher intensities
• WDS is presented without varying the intensity of presentation
• Presented at supra threshold level(s)
• The stimuli we use are called
• Phonetically balanced words (PB words)
• PB words are one syllable words

• Generally present at 40 dB SL
• Present 25-50 words at each level to each ear
• The score is simply % correct
• If presenting 25 words, each word is 4%

• NU-6
• PBK
• Mayo Clinic Graduate Word list
• Can stop after 10 words IF the patient gets the first 10 words correct
• The list is "graduate" so the hardest words are at the beginning
• If the patient misses even ONE word, you must present all 25 words

• Impact of hearing loss on speech understanding - can have same HL but different trouble understanding speech
• Helps indicate site of lesion
• Rehab strategies: hearing aids, assistive technology
• Verification of benefits of intervention: after giving amplification
• Monitoring performance: have baseline

• 80-100% WDS

• 0-100% depending on etiology and degree
• Loudness may or may not help
• distortion

Word Discrimination Score

"Rollover"

• Criteria for "concern"
• If "rollover" is present to a certain degree, we have concerns that neuromma could be present.
• Rollover is defined at different levels for different PB word lists
• NU-6: Rollover is defined as 20% worse performance at higher intensity
• PBK: Rollover is defined as 30% worse performance at higher intensity levels
• Rollover: A popular term for the shape of the curve in speech discrimination-SD audiometry, related to a defect in retrocochlear cranial nerve VII, in which SD improves as sound intensity increases until a maximum-PB max is reached, after which SD worsens. (see hearing test)
• If rollover is present, compare to other test results, and refer out or recommend:
• Electrophysiologic Testing
• Physician-MRI
• Physician-CT scan

• There are currently no "standards" in place for performance on WDS testing. (just a list that the professor has come up with that is in the notes)

• *20 dB below than presentation in other ear*

• Tells us about the outer hair cell function in the cochlea
• First described by Kemp in 1979, called them "cochlear echoes"
• Two broad catefories
• Spontaneous otoacoustic emissions (SOAE's)
• Evoked Otoacoustic Emissions (EOAE's)
• The creation of OAE's by the cochlea and the re-emission of this energy as sound from the ear serve no important physiological purpose that can be determined. Their clinical significance is that they are evidence of vital sensory process arising in the cochlea.

• Are present in approximately 50% of the population.
• Continuous tonal signal that can be recorded in the ear canal
• Frequency range (typical) 1-3 kHz
• Intensity (typical) -10 dB SPL to + 10 dB SPL
• Generally inaudible to the individual

• There are 2 general types of evoked OAE's
• Distortion Product Otoacoustic Emissions
• Transient Evoked Otoacoustic Emissions

• OHC contract to give soft sounds a "boost"
• When OHC contact for a small wave, they make a larger wave that is more easily perceived. They also send a wave in opposite direction, which is "backward" transduced through the ME to be measured in the ear canal as a sound

• The result is a sound that can be measured in the ear canal which gives us information about the function of the OHC's in the inner ear.
• There are formulae associated with how we elicit OAE's which let us look at OHC function at various locations along the basilar membrane. This way we can see what areas have been damaged or are functioning appropriately

• Stimulus is a tone "pip" or a clock
• Equipment uses "signal averaging" technology to determine what is a response and what is just "noise" in the EAC
• 260-500 stimuli are presented
• Stimulus is presented at about 80 dB
• Do no occur in persons with hearing loss greater than 30 dB HL

• Are essentially the same, but a different stimulus is used to elicit the response
• 2 tones are sent into the ear simultaneously by the unit
• The second tone (F2) is several hunderred Hz higher than the first tone (F1)
• This is determined scientifically
• Using these 2 frequencies (F1 and F2) a formula has been derived which determines where the GREATEST excitation will occur.
• 2F1-F2 = best, most reliable and consistent result
• The unit measures the response in the same way that a TEOAE's is measured

• Very useful clinically
• If there is any conductive pathology OAE's will be absent
• With infants and difficult to test patients, OAE's provide a WEALTH of information
• If we know how the cochlea is functioning, we know at leat PART of the hearing system is A-OK.

• NOT a hearing test
• High correlation between sensory hearing loss and OAE absence demonstrates that most sensory losses involves outer hair cell dysfunction (when normal outer and middle ear)
• OHC's are vulnerable to noise, oxygen deprivation, and ototoxic agents
• Primary purpose of test is to determine cochlear status, specifically hair cell function. This information can be used to
• screen hearing
• partially estimate hearing sensitivity within a limited range
• differentiate between the sensory and neural components of sensorineural hearing loss
• test for functional hearing loss

• The "response" has to be 3-6 dB above "noise floor"