SPA 4326

Type Ad (Deep

-Deep/steep -A normal shape but it has high admittance/low impedance; the TM is hypermobile -Deep (high) peak above 1.8 ml -May indicate ossicular discontinuity (floppy TM) or very thin TM from recurrent perforations

Bass, treble and the differences in how the sounds propagate; relative contribution to speech perception

Much of loudness in speech is carried in the bass components Clarity is mainly in the treble Talking louder doesn't always make it clearer

Suprathreshold: PI-PB

Normal / Conductive hearing loss, word recognition scores generally very good (>90%) Cochlear Hearing loss (hair cell damage) it can be difficult to predict the score, depends on amount of hearing loss in the speech banana, age, etc Retrocochlear Hearing Loss (tumors) generally have much poorer word recognition ability than you'd expect and can be characterized by "rollover" phenomenon

May I add dB values?

Not without an elaborate formula - 40 dB + 40 dB does not = 80 dB - in terms of pressure it would = 46 dB - in terms of power it would = 43 dB

OAEs Challenges

Patient must be still, quiet and the test room must be relatively quiet If emissions are absent, it does not tell you the degree of hearing loss Unable to obtain in those with middle ear disorders

Improving S/N

Preferential seating: Near the teacher and allowing clear view of the teacher's face; high frequency consonants are easier to speech read/lip read than are vowels Sound field systems: Speakers around the room; teacher wears a microphone; "auditory trainers," FM systems, remote microphones streamed to hearing aids

Bone conduction

Purpose: To determine hearing levels at the inner ear and bypass the outer and the middle ear Mastoid placement is most common and preferred among audiologists, but in theory you can place anywhere on the skull. Interaural attenuation of bone conduction is 0 dB Bone conduction (unmasked) testing yields the thresholds from the best hearing cochlea not the ear closest to the bone oscillator. Vibro-Tactile Responses Occur mostly at lower frequencies (250-500 Hz)

Pediatric Evaluation

REMEMBER TO GET THE MOST IMPORTANT INFORMATION FIRST As a rule, always try to get a tympanogram (but if kid is scared you may not be able to get the tympanogram first thing)

dB SL

Sensation Level, patient's own threshold, used for speech testing

SNR (signal-to-noise ratio)

The relation between the intensity level of the words and the intensity level of the background sound -With some speech-in-noise tests, SNR is varied to make the test easier with a larger SNR or more difficult with a smaller SNR. -The cocktail party effect occurs when background noise is present in a small group of speakers but, with some effort, a normal-hearing listener can understand what each speaker is saying -If speech is at 65 dB and noise is at 45 dB, the SNR is +20 -If speech is at 65 dB and noise is at 85 dB, the SNR is -20 -THE HIGHER THE SNR, THE EASIER IT IS TO UNDERSTAND SPEECH -Different people require different SNRs to function well -E.g., younger children may need +20 SNR in the classroom where intact young adults may function at -5 dB SNR -People with SNHL or neurologic decline will need higher SNR -Can't be predicted by the audiogram

ABR Advantages

Unlike OAE, can get auditory information on all different hearing levels (not just normal and mild) to diagnose hearing loss Often can get enough information to move forward with treatment plan (HA, CI, etc)

6 months to 2 years

VRA (visual reinforcement audiometry) ideally performed in soundfield under earphones ( does not provide ear specificity); can test tones and speech (remember! Testing in soundfield does not provide ear specificty) In sound field no ear-specific information is obtained Response is from the better ear

Diagnosing hearing loss in babies and children

When deciding which test method to use, consider the developmental age of the child, not chronological

PB Max

With conductive loss, WRS is usually very good

Suprathreshold - Word Recognition Score (WRS) (formerly Speech Discrimination Score: SDS)

Word Recognition Testing -Part of the standard audiometric battery; tested via air conduction -Single syllable PB words -Carrier phrase ("say the word ____") -Generally presented at 40 dB above SRT (40 dBSL) or as high as possible without exceeding the patient's UCL if UCL<40 dBSL -Scored as % correct -Testing a single level may be misleading; sometimes best practice is to test multiple levels (PI-PB function) 2 people with the same audiogram may have different WRS - perhaps more cochlear distortion, central nervous system issues

octaves

an increase of an octave is a doubling of frequency -sounds at octave multiples are perceived as the same musical note

2 to 5 years

conditioned play audiometry- speech testing is often done first (before pure tones) by having child point to pictures or body parts. For older cooperative children with clear speech, may obtain an SRT just like adults -Physiological tests are mainly for behavioral test results not for testing hearing -OAEs (Otoacoustic Emissions): emissions originate in the outer hair cell of the cochlea (in a normal functioning ear) and the emissions travel outward through the middle ear bones and into the ear canal where we measure them with a sensitive microphone.

Mixed Hearing loss

hearing is reduced due to a problem in both the outer or middle ear and the inner ear - Bone conduction is not normal but air conduction is worse

Sensorineural hearing loss

hearing is reduced due to a problem in the inner ear but the outer and middle ear functions normally - Air and bone are the same or very close

Conductive hearing loss

hearing is reduced due to a problem in the outer or middle ear but inner functions normally

Amplitude

loudness (the subjective impression of the power of a sound); describes the intensity of sound - psychoacoustic correlate is loudness

Cross-hearing (crossover)

occurs whenever a stimulus exceeds the IA (interaural attenuation) E.g., stimulus is 80 dB, IA is 55. Therefore 35 dB is present at the non-test ear.

Clinical audiometer

part of the diagnostic and computer based audiometers -offer a multitude of test options -computer based audiometers use mouse, keyboard, and computer monitor

1-3-6 rule of newborn tests

screening by one month, diagnosis by 3 months, habilitation (hearing aids, therapy) by six months

Speech audiometry

stimuli and the different types of speech tests -PTA, pure tone average: 3 Frequency Pure Tone Average of 500, 1000, and 2000 Hz should correlate with Speech Recognition/Reception Threshold (SRT) -PTA is always calculated from the air conduction thresholds, NOT bone conduction thresholds

Dynamic Range

the amount of usable hearing (UCL - SRT) 1) Normal patient has an SRT of 10 and a UCL of 90 dB, dynamic range = 80 dB 2) Patient has an SRT of 60 dB and a UCL of 90 dB, dynamic range = 30 dB

Interaural attenuation

the isolation or attenuation produced by the head when sound is presented to one ear before it crosses over to the other (non-test ear). IA is greater for insert earphones (at least 60 dB) than for supra-aural earphones (at least 40 dB). There is no IA for bone conduction. •Interaural attenuation of bone conduction = 0 dB •Regardless of where you place the bone oscillator on the head, the better hearing cochlea will always respond

Relationship between bass, treble, stiffness, mass

things with a lot of mass, or more elastic, have lower bass sounds •Low frequency sounds are Bass •Longer wavelengths...bigger speaker cones •Larger, heavier, less stiff things have lower resonant frequencies • Thicker, looser, longer guitar strings •Think lazy snakes •Travel corners well •Don't dissipate much over distance in a room •Most "background" ambient noise •Don't carry as much speech information • Think Charlie Brown's teacher's voice • "mumbling" things with less mass, more stiff, have higher pitched treble sounds •Treble •Shorter wavelength: smaller, lighter, stiffer speaker cones •Smaller, lighter, stiffer things have higher resonant frequencies •Thinner, tighter, shorter guitar strings •Bounce off surfaces in straighter lines •Don't travel corners well or persist as well in a room •Very important speech components, but also soft phonemes

Masking for speech testing

• Same rules as pure tone test masking • Masking is needed when test stimuli levels exceed IA values* • Headphone IA for speech ranges from 40-45 dB • Insert earphone IA for speech ranges from 55-65 dB • Detection could be as low as 35 dB • Masking type needs to match test materials (speech noise vs. narrowband noise) • Single level of masking is typically used; generally do NOT search for a masking plateau

Masking

• There are times during a test when we put noise into the non-test ear • Masking noise • For pure tones use narrowband noise (NBN) centered around the frequency you are testing (I usually just tell my patients they will hear static) • For speech use "speech noise" which covers the frequency range of speech • Why mask? Because there are times when we deliver a sound to the test ear, but the non-test ear hears it. This is called crossover, or cross-hearing. We want to know that we are testing the ear we intend to test, therefore we mask.

Sound Pressure Level (SPL)

•0dB SPL (this is not silence), it's just compared to the reference pressure level •140db SPL=threshold of pain for humans

WRS

•Monosyllabic PB words are an open set and are more difficult •Therefore, the PI function is not as steep as for SRT

SRT

-Most important reason to obtain SRT in adults is to cross check pure tones -SRT should be consistent with the PTA; if not, suspect functional/nonorganic loss -Can't predict shape, but it should correspond to best hearing areas in the 500, 1000 & 2000 Hz range +/- 10 dB rule

Physiological Tests

-Remember! Physiological tests are NOT a test of hearing. However, they often correlate with hearing levels and for some populations they give you the best estimate of hearing. -Never forget that the "gold standard" for both threshold determination and for showing that hearing has occurred is behavioral audiometry. -This is because behavioral audiometry requires a signal to be detected, perceived and acted upon -Ascending and descending pathways -Physiologic tests for the most part don't imply full perception/understanding -When possible, physiological test results should be combined with behavioral tests

Benefits of Speech Testing

-Results correspond with patient complaints -Helps predict/validate Pure Tones -Helps predict hearing aid success -Hard to test populations

Type As (shallow)

-Shallow/ Stiff -This tympanogram has a peaked shape but it has high impedance/low admittance so it is a stiff system -Shallow peak (2 ml or less) -May indicate otosclerosis -However, many cases of otosclerosis will have type A with absent acoustic reflexes

Bell's Palsy

-The afferent arc of the reflex is from CNVIII, the auditory nerve. -The efferent arc of the reflex (where it is recorded) is from CN VII, the facial nerve. Bell's Palsy is facial nerve paralysis. -Serial testing of acoustic reflexes is done to monitor the course of Bell's Palsy

Middle Ear: Function

-The middle ear system serves the important function of matching the low resistance (impedance) of the air in the external ear canal to the high resistance or impedance of the fluid within the inner ear. -The impedance matching middle ear system is important for normal hearing. Three factors contribute to increased energy related to sound pressure as it passes from the ear canal through the middle ear to the inner ear: -The tympanic membrane is considerably larger in area than the stapes footplate -The ossicles connecting the tympanic membrane to the inner ear fluid function as a lever -The shape of the tympanic membrane contributes to an increase in the sound pressure reaching the inner ear

Masking for air conduction

-There are times when we also must mask for air conduction. We mask less often for air conduction testing than for bone conduction testing because it takes more energy for cross hearing to occur (i.e., the IA is higher) -With sufficient intensity of an air conduction stimulus, the resulting vibration of the earphone will be transferred to the skull and will travel to the non-test ear. -Headphones sit against bone whereas inserts sit against cartilage -The inter-aural attenuation for air conduction depends on the type of ear phone (or transduscer) -Supra-aural headphones = 40 dB -Inserts = 55 dB

Test Methods (2)

1. Threshold measures- closet set: multiple choice; easy test 2. Supra-threshold measures- open set: open ended questions; you do not know what the word is; difficult test

Threshold Measures

Speech Recognition Threshold or Speech Reception Threshold (SRT)

2 muscles in the middle ear (acoustic reflexes)

Stapedius and Tensor tympani

MCL (most comfortable level)

hearing level judged by a listener to be comfortable (not too loud and not too soft). The level at which most people prefer to listen to sound.

treble

higher frequency sounds; shorter wavelengths

bass

low frequency sounds; longer wavelengths

Infants to 6 months

physiological measures (ABR/OAE) "gold standard" at this age because behavioral responses are NOT reliable

Frequency

pitch (the subjective impression of the highness or lowness of a sound); how often a vibration repeats itself which is expressed in Hertz (cycles per second/cps)

Threshold

the lowest intensity level a person reliably responds 50% of the time

dBHL (hearing level)

•Intensity on audiograms is expressed in dB HL to "flatten" the dB SPL curve •dBHL values were refined over time and are set by ANSI •Regardless of the reference scale (SPL, HL, nHL, A, C), dB is still a logarithmic ratio •+6 is a doubling of pressure •+3 dB is a doubling of power •An increase by 10 phon is a doubling of perceived loudness •Approximately 10 dB for 1 kHz - the zero phon line= 0 dB HL

SRT

•Remember spondees are from a closed set of words •Spondees are easy to recognize •Therefore, the PI function is steep. •Goes from 0 to max quickly with increased intensity

Decibel (dB)

•Unit of measure to express the ratio between two sound pressures (1/10 of a Bel) •dB is not a direct measure; it is always a ratio to a reference point •Involves a ratio and a logarithm •It is non-linear. Human hearing is also non-linear •It is a relative unit of measure •Is expressed in terms of various reference levels which must be specified (SPL, HL, nHL, SL)

Organ of Corti (inner ear)

*a complex of structures located on the basilar membrane of the cochlea. •This complex structure plays a critical role in hearing. •Rods and pillars form its main supporting framework and enclose the tunnel of Corti. -Stereocilia for inner hair cells are arranged in a single row on the medial side of the organ of Corti. -The tallest stereocilia on the top of outer hair cells are imbedded within the soft undersurface of the tectorial membrane.

Inner Ear Function

- Also responsible for equilibrium through the vestibular system - Semi-circular canals - Otolith organs - Utricle - saccule

Outer hair cells

- Change shape when activated - Outer hair cell movement produces energy in the inner ear that enhances hearing.

Inner hair cells

- Communicate with auditory nerve fibers - Release a chemical that produces a response in auditory nerve fibers when they are activated by vibrations - The electrical activity within auditory nerve fibers is transmitted quickly to the brain

Inner ear hair cells

- inner hair cells -outer hair cells

Acoustic Reflex Decay

-A healthy system should be able to hold a reflex contraction for at least 5 seconds -An VIII nerve tumor (acoustic neuroma) may cause inability of the nerve to sustain adequate neural function and the reflex will"decay" more than 50% within 5seconds -Positive reflex decay = potential tumor -Normally test at 500 Hz and at 1kHz -Positive reflex decay is a red flag for retrocochlear disorder such as an acoustic tumor

Why Test Acoustic Reflexes

-AR help us assess for the following problems: -CN VIII (auditory nerve) lesions, such as acoustic neuroma -CN VII (facial nerve) lesions (Bell's Palsy) -(Rarely) brainstem lesions -AR also help us determine if a hearing loss is conductive in cases where other results might be conflicting (AR will be absent when there is a CHL) -AR can help us assess if someone is presenting a functional(nonorganic) hearing loss Bell's Palsy

Outer Ear: Function

-Concave shape helps to collect and amplify sound and to funnel the sound into the external ear canal. -The bowl-shaped concha increases sound levels by up to 10 to 15 dB in the frequency region of 4500 Hz. -Outer ear enhances the detection of sounds coming from the direction a listener is facing. -It enhances localization which is the process of determining where a sound is coming from.

Reflexes

-DO not test reflexes if patient has poor loudness tolerance(hyperacusis) -The reflex stimulus must be below the UCL -The presence of a reflex does not rule out SNHL -Reflex will usually be absent for severe or profound SNHL, but present for lesser degrees of loss -Audiometric thresholds cannot be inferred from acoustic reflex thresholds

Effects of undiagnosed hearing loss in children:

-Delays in receptive and expressive communication -More likely to be inattentive/misbehave -Academic delays lead to vocational limitations -Social isolation -The academic gaps widen with time, these children may not "catch up" -Incidence of permanent hearing loss in infants is 1.5/1000

Otoacoustic Emissions (OAEs)

-Emissions originate in the outer hair cell of the cochlea (in a normal functioning ear) and the emissions travel outward through the middle ear bones and into the ear canal where we measure them with a sensitive microphone -OAEs are found in normal functioning cochleae (mainly the OHCs) VERY soft sound (-10 to 20 dB SPL), inaudible without special equipment -People with normal hearing produce OAEs. -A mild/moderate hearing loss (of any kind) or greater will obliterate an OAE -Pre-neural -Non-behavioral (often used as newborn hearing screen) -Quick -When we obtain OAEs, we can make some assumptions -Hearing is likely normal to no worse than mild -Middle ear function is normal (middle ear disorder will OBLITERATE an OAE)

Signal to Nose Ratio (S/N)

-For our purposes, synonymous with Speech to Noise Ratio -Ratio of the intensity of the desired signal to the "background noise" -If speech reaches the ear at 45 dB SPL and the noise is 55 dB SPL, S/N=-10 dB

Suprathreshold Measures

-Generally trying to answer, "In the best case scenario where speech is at an intensity high enough to be heard well, how well does a patient understand speech?" -Why? -Predicts hearing aid success -Correlates with type of hearing loss -Helps identify retrocochlear disorders (tumors)

Why is the inverse square law important?

-HUGE impact on speech intelligibility -The farther you are from the speech source, the softer the speech -The important high frequency speech sounds are less intense at the source; with distance they fade away and may not be detectable -Meanwhile, low frequency competing sounds (coughing, rumbling, moving desks, shuffling, air conditioners, lawn mowers outside the window) may be closer to the listener than is the desired signal -The combination of the inverse square law, reverberation, and the different properties of bass vs. treble propagation and perception are contributors to the problem of "background noise"

Type A (normal)

-If there is no conductive hearing loss on the audiogram, can infer that the middle ear system is normal -If there is conductive hearing loss, suspect ossicular abnormality

mass vs. stiffness

-More massive things carry bass sounds better -Stiffer things carry treble sounds better -By inverse, stiffer things do not transmit bass as well THEREFORE: -Problems that stiffen the ear system cause more hearing loss in the lower frequencies (stiffness tilt) -Problems that introduce more mass in the system are called "mass weighting" and affect all frequencies

Requirements for Speech Testing

-Patient must be familiar with the language of the test words -Sometimes speech testing cannot be done with validity -Patient must be familiar with the vocabulary used -E.g., not many children are familiar with "inkwell" or "mew" -The response task must be something the patient is able to do -Sometimes you may have the patient point to pictures or point to body parts -A task that shows that the target word is recognized

Why OAE

-Physiological tests gold standard under 6 months -To obtain ear specific information on a child when all you have is soundfield -To confirm what you are getting -behaviorally (in children and adults) -To assess for "dead regions" when you fit hearing aids -Quick and easy Note: OAE is pre-neural and both ABR and ASSR are pre-cortical (before the level of the cerebral cortex) so none of them are affected by sedation.

Houghson-Westlake Procedure

-THE standard way to find threshold for pure tones -ALWAYS use this technique -Robust and reliable -Regardless of examiner -Test/retest -It is not acceptable to think you have a quicker way -Order of tones tested -Generally start at 1 kHz then progress to 8 kHz -1 kHz the most stable regardless of problem -Then test 250 Hz and 500 Hz -Present tone for approximately 2 seconds -May use pulsed tones, esp. with tinnitus -Vary timing to avoid rhythm -No visual cues -No coaching - When you get a response, drop 10 dB -No response, raise 5 dB -Threshold is 2 out of 3 responses at the same level in ascending trials

How does the middle ear amplify and bridge impedance mismatch?

30 dB increase, acoustic to mechanical energy; the ossicles are what's bridging the impedance mismatch as the ear goes from air to fluid

Performance Intensity Function for Phonetically Balanced Words (PI-PB)

As the presentation level rises, word recognition scores also rise until at some point the word recognition score reaches asymptote (maximum). Increasing the presentation level doesn't improve your word recognition ability any further (this level is "PB Max") Performance-Intensity function for various stimuli

Why Immittance Testing

Audiograms quantify hearing loss and provide information about the "site of lesion" but they don't tell us why Immittance tests give us information about the middle ear system to help localize pathology Immittance is an engineering term combining admittance and impedance

How much the non-test ear hears depends on inter-aural attenuation (IA)

Every transducer has its own IA (the following values are conservative) -Bone = 0 dB -Headphones = 40 dB -Inserts = 55 dB Cross-hearing or crossover occurs whenever a stimulus exceeds the IA E.g., stimulus is 80 dB, IA is 55. Therefore 35 dB is present at the non-test ear. . We mask for bone conduction and air conduction for pure tones and for air conduction for speech

Testing Considerations

False Positives-patient responds when no sound is present (tinnitus, highly anxious, kids!) False Negative-patient does not respond even when a sound is audible (malingerer, someone who doesn't understand task like dementia pts or kids?)

Why ABR

For babies/young children to identify hearing loss or confirm suspected hearing loss (can be a screening for newborns performed by a technician or a diagnostic evaluation to diagnose and quantify hearing loss performed by an audiologist) -Automated ABR is a screening

Limitations of sound field tests:

In the example babies 6 mos. to 2 yrs, VRA (Visual Reinforcement Audiometry): Ideally performed under earphones, usually performed in soundfield (remember! Testing in soundfield does not provide ear specificity) -In sound field no ear-specific information is obtained -Response is from the better ear

relationship between frequency and wavelength

Inversely proportional, the shorter the wavelength, the higher the frequency and vice versa

Amplifies sound due to:

1) The area differences between the TM and the oval window 2) Curved membrane 3) Lever advantage

Acoustic reflexes

-These muscles contract (stiffen the middle ear system) in response to loud sound -We can detect the contraction of the stapedius muscle using an Immittance Bridge to measure the change in stiffness/impedance -The pattern of contractions gives us information to help localize pathology along the auditory system -Generally test reflexes at 500, 1000 and 2000 Hz in both ipsilateral and contralateral conditions -Ipsilateral = both the loud tone and the probe measuring the reflex are in the SAME ear -Contralateral = the stimulus tone is in one ear and the probe measuring the reflex is in the OPPOSITE ear -The acoustic reflex is normally a BILATERAL response; if aloud tone is presented to one ear, both stapedius muscles will contract (regardless of the stimulus ear) -An intact ("present") reflex relies on integrity of the VIII and VII cranial nerves, as well as the lower brainstem.(The acoustic Reflex Arc) -If there is conductive or a mixed hearing loss, the reflex will be absent

Type C

-Think "retraCted" (or EustaChian tube problem), this tympanogram has a peak, but the peak is at significantly negative pressure -Atmospheric pressure is at 0. Type C has a peak at -100-150 daPa or lower -Indicates Eustachian tube dysfunction ETD -Negative middle ear pressure with common cold (URI), air travel, sinus trouble, hypertrophic (enlarged) adenoids -When the air in the middle ear is used up and the Eustachian tube does not let more air in, the TM is retracted (sucked in). -At 0 pressure, the system is stiff. -When negative pressure (vacuum) is introduced to the ear canal, the peak will occur at the level of negative pressure in the middle ear. -Often get type C before and after middle ear fluid -Approximately 10 dB of low frequency hearing loss for every 100 daPa of negative pressure -Stiffness causes a LOW frequency hearing loss/rising audiogram -"Stiffness tilt"

Tympanometry

-Tympanograms can reveal: -Fluid behind the eardrum (serous otitis media) -TM perforation (hole) *Trauma/injury *Pressure Equalization (PE) tube -Negative pressure behind the eardrum (Eustachian tube dysfunction) -Tympanograms can help us predict the type but not necessarily the severity of hearing loss (one can, however make inferences about the degree of loss) OFTEN TIMES IT IS BEST TO DO IMMITTANCE TESTING BEFORE AUDIOMETRY WHEN TO DEFER TYMPANOMETRY -with a fearful child wait until after you get other results -If there is drainage in the ear canal -If the pain reports pain, dizziness or nausea with tympanometric pressure changes

Type B

-Type B with large ECV -B is flat, does not have characteristic shape (no peak), flat line, but volume is big because the probe is measuring the middle ear space as well as the ear canal space -Indicates a hole in the TM ora patent (open) PE tube in the ™ -Ear canal volume measure is of vital importance with Type B

Auditory Brainstem Response (ABR)

-Used to assess the neurological function from the VIII cranial nerve through the brainstem. -ABR is just one of a family of tests known as "auditory evoked potentials." -Characterized by a series of Waveforms I-V -NOT a test of hearing but highly correlated with hearing levels (i.e. when the nerve responds to a sound, we can infer that the person would perceive/hear that sound) -Must be quiet: after 3 months generally have to test under sedation

Screening Audiometers (portable)

-used for health screenings, for bedside testing in hospitals -limited functions, sometimes only a pass/fail option