Diagnostic

Purpose:

To determine the softest sound (threshold) a person can hear at various frequencies (pitches), usually between 250 Hz and 8000 Hz.

Procedure:

1. The person is seated in a soundproof booth.
2. They wear headphones (for air conduction testing) and/or bone oscillator (for bone conduction testing). 
3. Pure tones of different frequencies are presented at different intensity levels. 
4. The person signals (usually by pressing a button or raising a hand) whenever they hear a sound.
5. The lowest volume at which a sound is heard 50% of the time is recorded as the threshold.

Types of Conduction Tested:

1. Air Conduction – via headphones; tests the entire hearing pathway.
2. Bone Conduction – via bone oscillator on the mastoid bone; bypasses outer and middle ear, directly stimulating the cochlea.

Results:

• Recorded on an audiogram, a graph plotting hearing thresholds (in decibels, dB HL) against frequencies (in Hertz, Hz). 
• Normal hearing: 0–25 dB HL across frequencies.
  

 Interpretation:

It helps to determine:

• Degree of hearing loss (mild, moderate, severe, profound)
  
• Type of hearing loss:
  
  • Conductive (problem in outer/middle ear)
  • Sensorineural (inner ear or nerve)
    
  • Mixed
     

Clinical Uses:

• Diagnosing hearing loss 
• Fitting hearing aids
• Monitoring hearing (e.g., in noise-exposed workers or patients on ototoxic meds)
• Part of pre-surgical assessment for ear conditions

 Purpose:

Impedance audiometry evaluates the function of the middle ear, including:

• Tympanic membrane (eardrum) mobility
  
• Ossicular chain movement (middle ear bones)
  
• Eustachian tube function
  
• Presence of fluid, perforation, or pressure issues
  

Clinical Significance:

• Detects:
  
  • Otitis media (middle ear infection)
    
  • Eustachian tube dysfunction
    
  • Tympanic membrane perforation
  • Ossicular chain discontinuity
  • Otosclerosis
    
• Can be used in infants and uncooperative patients as it is an objective test.
  

Advantages:

• Non-invasive
  
• Quick (usually 2–5 minutes per ear)
  

Objective (no need for patient response)

Purpose of ECochG:

• Diagnose Meniere’s disease (endolymphatic hydrops)
  
• Assess auditory nerve function
• Intraoperative monitoring during ear surgery
• Evaluate cochlear and auditory nerve integrity in hearing-impaired patients
   

 How It Works:

• A click or tone burst sound stimulus is presented to the ear.
  
• Electrodes record the resulting electrical activity:
  
  • Transtympanic (needle electrode through the eardrum; more invasive, more accurate)
    
  • Extratympanic (electrodes placed in the ear canal or on the eardrum)
    

Main Components Measured:

1. Cochlear Microphonic (CM):
• Mimics the sound stimulus. 
• Generated by outer hair cells in the cochlea.


2. Summating Potential (SP): 
• A direct current (DC) shift during stimulation.
  
• Reflects hair cell activity, especially inner hair cells.
  


3. Action Potential (AP): 
• Corresponds to Wave I of the auditory brainstem response (ABR).
  
• Represents auditory nerve firing.
   

 Clinical Uses:

Condition	Role of ECochG
Meniere’s disease	Detects elevated SP/AP ratio
Auditory neuropathy	Helps differentiate sensory vs. neural issue
Perilymphatic fistula	Assists in diagnosis
Intraoperative monitoring	Monitors cochlear function during surgery

Purpose of ETF Testing:

To assess whether the Eustachian tube is:

• Opening properly during swallowing or yawning 
• Allowing adequate pressure regulation
• Contributing to middle ear disorders such as otitis media, barotrauma, or Eustachian tube dysfunction
   

Methods of Testing:

1. Tympanometry-based ETF Test (Non-perforated eardrum):

• A baseline tympanogram is recorded.
• The patient performs swallowing or Valsalva maneuver (forced exhalation with the nose pinched).
• Changes in middle ear pressure are measured.
• Normal Function: Pressure in the middle ear changes in response to maneuvers.
  

2. ETF Test with Perforated Eardrum or Vent Tube:

3. Sonotubometry:

• Uses a sound source in the nose and a microphone in the ear canal.
• Sound passes through the Eustachian tube during swallowing.
  
• Presence of sound in the ear canal = patent tube.
  

4. Nasopharyngoscopy:

Interpretation:

Clinical Significance:

ETF testing helps diagnose:

• Chronic otitis media with effusion 
• Barotrauma (e.g., flying/diving problems) 
• Hearing loss due to middle ear pressure issues
• Eustachian tube dysfunction (ETD) 
• Patulous Eustachian tube (open all the time—causes autophony) 

Symptoms of ETF Dysfunction:

• Feeling of fullness or pressure in the ear 
• Hearing loss 
• Popping or crackling sounds
• Discomfort with altitude or pressure changes

Diagnosis of Tinnitus:

1. Detailed Patient History:

• Onset, duration, frequency, pitch
• Unilateral vs. bilateral
• Associated symptoms: hearing loss, vertigo, ear fullness, headache
• Noise exposure, medication use (e.g., ototoxic drugs), stress/anxiety

2. Audiological Evaluation:

• Pure Tone Audiometry (PTA): Check for hearing loss (most tinnitus patients have some degree of hearing loss)
• Tinnitus Matching Tests:
• Pitch Matching
• Loudness Matching
• Minimum Masking Level (MML)

3. Immittance Testing:

• Tympanometry to rule out middle ear pathology

4. Otoacoustic Emissions (OAEs):

• Detect cochlear (outer hair cell) function

5. Auditory Brainstem Response (ABR):

• Rule out retrocochlear pathologies (e.g., vestibular schwannoma)

6. Imaging:

• MRI (internal auditory canal): If unilateral tinnitus, asymmetrical hearing loss, or neurologic signs

Causes of Tinnitus:

Management of Tinnitus:

1. Education and Counseling:

• Reassure the patient — tinnitus is not dangerous
• Explain the connection to hearing loss, stress, and the brain
• Avoid silence; use low-level background sound

2. Treat Underlying Cause:

• Remove earwax, treat ear infections
• Discontinue ototoxic drugs
• Manage Meniere's disease, TMJ, or cervical issues

3. Hearing Aids:

• For patients with hearing loss
• Amplification can reduce tinnitus perception

4. Sound Therapy:

• Use of white noise, nature sounds, or customized tinnitus maskers
• May be delivered via hearing aids, apps, or standalone devices

5. Cognitive Behavioral Therapy (CBT):

• Proven effective
• Helps reduce emotional distress and negative reaction to tinnitus

6. Tinnitus Retraining Therapy (TRT):

• Combines sound therapy + counseling
• Aims to habituate the brain to tinnitus over time

7. Medications (Limited Role):

• No drug cures tinnitus, but some may help with symptoms:
• Anxiolytics / Antidepressants (for comorbid anxiety/depression)
• Melatonin (for sleep issues)
• Ginkgo biloba (evidence inconclusive)

Purpose of OAE Testing:

• Assess cochlear (outer hair cell) function
• Detect early hearing loss
• Screen newborns and infants
• Differentiate cochlear (sensory) hearing loss from neural hearing loss (e.g., auditory neuropathy)
• Evaluate non-cooperative or difficult-to-test patients

How It Works:

• A small probe is inserted into the ear canal.
• The probe emits sounds (clicks or tone bursts) and records any sound (emission) that bounces back from the cochlea.
• The presence of emissions indicates normal outer hair cell function.

Types of OAEs:

Classification and Description:

Clinical Applications:

Population / Situation Based Use:

Purpose of BERA Testing:

• Assess hearing sensitivity (especially in infants or uncooperative patients)
• Screen for retrocochlear lesions (e.g., acoustic neuroma)
• Diagnose auditory neuropathy spectrum disorder (ANSD)
• Evaluate neural conduction delays
• Intraoperative monitoring during neurosurgeries
• Newborn hearing screening (in some protocols)

How It Works:

• Electrodes are placed on the scalp and earlobes/mastoid.
• Clicks or tone bursts are presented through earphones.
• The system records neural responses over time (within the first 10 milliseconds after sound).
• The waveform shows seven peaks (waves I–VII), each representing activity at a specific point in the auditory pathway.

Clinical Applications:

Purpose of ASSR Testing:

• Estimate hearing thresholds at specific frequencies (e.g., 500, 1000, 2000, 4000 Hz)
• Diagnose degree and configuration of hearing loss (mild → profound)
• Evaluate candidates for hearing aids or cochlear implants
• Screen newborns and children for hearing loss
• Useful in profound or asymmetric hearing loss where BERA may be limited

How It Works:

• The patient wears earphones, and modulated tones (amplitude and/or frequency modulated) are presented.
• Electrodes placed on the scalp record brain activity in response to these tones.
• The system analyzes the steady-state neural response (like a continuous waveform), which corresponds to the specific modulation frequency.
• The brain’s response is analyzed using Fast Fourier Transform (FFT) to determine if a response is statistically present at each frequency.

Clinical Applications:

Use Case and Description:

Purpose:

• Assess the functional benefit of hearing aids or implants.
• Verify that the hearing device is appropriately programmed.
• Measure aided hearing thresholds across different frequencies.
• Help in auditory rehabilitation and device adjustment.

Types of Aided Audiometry:

Sound Field Audiometry:

• Performed in a sound-treated booth using loudspeakers.
• Both ears are tested together (binaural hearing) unless one ear is occluded or masked.
• Sounds are presented in the free field with the device on.

Aided Speech Audiometry:

• Measures speech detection, speech recognition, or speech discrimination with the hearing device on.
• Tests include:
• Speech Reception Threshold (SRT)
• Speech Discrimination Score (SDS)
• Speech-in-noise tests

A. Tone Decay Test (TDT)

Purpose:

• Detect retrocochlear pathology (lesions beyond the cochlea, e.g., auditory nerve tumors).
• Assess the ability of the auditory system to sustain perception of a tone over time at threshold levels.

Procedure:

• Present a continuous pure tone at the patient’s hearing threshold.
• Ask if the tone remains audible over a period (typically 60 seconds).
• If the tone fades or disappears, increase the intensity to see if the patient can hear it again.
• Repeat this cycle and record how much the tone decays.

B. Short Increment Sensitivity Index (SISI) Test

Purpose:

• Evaluate the ability to detect small changes (increments) in loudness.
• Differentiate cochlear from retrocochlear lesions.
• Identify cochlear (sensory) pathology.

Procedure:

• Present a continuous tone at 20 dB above the patient’s threshold.
• Introduce small, brief increments in intensity (usually 1 dB).
• The patient signals when they detect the increment.
• Repeat for about 20 increments and calculate the percentage detected.

Clinical Relevance of TDT & SISI:

Purpose:

• Evaluate patients with dizziness, vertigo, balance disorders, and suspected vestibular pathology.
• Differentiate between central (brain-related) and peripheral (inner ear) causes of vertigo.
• Assess ocular motor function and vestibulo-ocular reflex (VOR) integrity.

How VNG Works:

• Infrared cameras track eye movements in complete darkness or with visual stimuli.
• Eye movements are recorded during a series of tests:
• Oculomotor tests: Smooth pursuit, saccades, gaze fixation
• Positional testing: Changes in head/body position
• Caloric testing: Warm and cold air or water irrigation of the ear canals to stimulate the vestibular system

Components of VNG Testing: