Tuning Fork Tests in ENT | Rinne, Weber, Absolute Bone Conduction, Schwabach, Bing & Gelle Test

🎵 Tuning Fork Tests

Tuning fork tests are important clinical tests used to determine the type of hearing loss a patient may have.

In this post, we will discuss:

• Rinne's Test
• Weber's Test
• Schwabach's Test
• Absolute Bone Conduction (ABC) Test
• Bing's Test
• Gelle's Test

Basic Principles of Tuning Fork Tests

🎚️ Frequencies of Tuning Forks

Tuning forks are available in the following frequencies:

• 128 Hz
• 256 Hz
• 512 Hz
• 1024 Hz
• 2048 Hz
• 4096 Hz

Commonly used in routine practice:

• 256 Hz
• 512 Hz
• 1024 Hz

Which is the most Preferred frequency of Tuning Fork used? Why?

🔔 How to Activate a Tuning Fork

The tuning fork is vibrated by striking it against:

• Examiner's elbow
• Heel of the hand

❌ Never strike it on a hard surface

Why should you never strike a tuning fork on a hard surface?

Air Conduction & Bone Conduction

Tuning fork tests assess two things:

1- Air Conduction (AC)

2- Bone Conduction (BC)

👂 Air Conduction

How is it Tested?

The vibrating tuning fork is placed vertically, parallel to the external auditory canal, at a distance of about 2 cm from its opening.

Pathway of Air Conducted Sound

External auditory canal → Tympanic membrane → Ossicles → Cochlea → Auditory nerve → Central auditory pathway

What does Air conduction Test?

⭐ Normally, air conduction is louder and longer than bone conduction.

🦴 Bone Conduction

How is it Tested?

The footplate of the vibrating tuning fork is placed firmly on the mastoid process.

Pathway of Bone Conducted Sound

Bone conduction directly stimulates the cochlea, bypassing the external and middle ear.

What does Bone conduction Test?

Types of Hearing Loss

1- Conductive Hearing Loss

Caused by a blockage anywhere in the conductive pathway.

Example: Wax in the external auditory canal

• Air conduction → Reduced
• Bone conduction → Normal (bypasses external and middle ear)

2- Sensorineural Hearing Loss

Caused by damage to the sensorineural pathway.

• Bone conduction → Reduced

Rinne's Test

🩺 How is it Performed?

1- Vibrating tuning fork is placed on the mastoid process

2- Patient indicates when he stops hearing the sound

3- Tuning fork is immediately shifted 2 cm in front of, and parallel to, the external auditory canal

4- If the patient still hears the sound → Air conduction is more than bone conduction

What is the Principle of Rinne's test?

Instead of comparing duration, what other parameter canbe compared in Rinne's test?

📊 Interpretation

Why is AC > BC in Sensorineural hearing loss?

Why is BC > AC in Conductive hearing loss?

💡 Mnemonic to remember Rinne test findings

CORN & SERP

• CORN → COnductive hearing loss → Rinne Negative
• SERP → SEnsorineural hearing loss → Rinne Positive

📏 Predicting the Air-Bone Gap Using Rinne's Test

The air-bone gap can be predicted even before audiometry.

⚠️ False Negative Rinne (Important MCQ)

👉 Seen in Severe unilateral sensorineural hearing loss

What is the mechanism behind False negative Rinne seen in Severe unilateral sensorineural hearing loss?

How to Avoid a False Negative Rinne?

• Mask the non-test ear with Barany's noise box before performing bone conduction

What is Barany's noise box?

Weber's Test

🔍 Principle

Based on lateralization of sound through bone conduction.

• Weber's test is a test of bone conduction
• Therefore, it is a test of cochlear function

Weber's test determines:

✅ Side of hearing loss

✅ Type of hearing loss

❌ Does not determine degree of hearing loss

🩺 How is it Performed?

The vibrating tuning fork is placed on the:

• Middle of the forehead
• Vertex

The patient is asked in which ear the sound is heard better.

📊 Interpretation

Explain the mechanism behind the findings seen in Weber's test in Conductive hearing loss and Sensorineural hearing loss.

Which test is more sensitive - Rinne's test or Weber's Test? Why?

Schwabach's Test

🔍 Principle

Compares the bone conduction of the patient with that of the examiner, assuming the examiner has normal hearing.

The type of hearing loss is determined by comparing the duration of bone conduction.

🩺 How is it Performed?

1- Vibrating tuning fork is placed on the patient's mastoid process

2- Patient signals when he stops hearing the sound

3- Tuning fork is immediately placed on the examiner's mastoid

4- Examiner checks whether the sound is still heard

📊 Interpretation

Explain the mechanism behind the findings seen in Schwabach's test in Conductive hearing loss and Sensorineural hearing loss.

Absolute Bone Conduction (ABC) Test

📌 Also Known As Modified Schwabach's Test.

🔍 Principle

• Compares the bone conduction of the patient with that of the examiner
• Air conduction is blocked by occluding the external auditory canal by pressing the tragus inwards

What is the Absolute Bone Conduction Test checking?

Why is Absolute Bone Conduction Test also known as Modified Schwabach's Test?

🩺 How is it Performed?

1- External auditory canals of both patient and examiner are occluded by pressing the tragus inwards

2- Vibrating tuning fork is placed on the patient's mastoid process

3- Patient signals when he stops hearing the sound

4- Tuning fork is immediately placed on the examiner's mastoid

5- Examiner checks whether the sound is still heard

📊 Interpretation

Why is there No Role of Absolute Bone Conduction Test in Conductive Hearing Loss?

⚖️ Schwabach's Test vs ABC Test

Which test is more sensitive - Absolute Bone Conduction test or Schwabach's Test? Why?

Bing's Test

🔍 Principle

• Test of bone conduction
• Tests the effect of ear canal occlusion on hearing

🩺 How is it Performed?

1- Vibrating tuning fork is placed on the patient's mastoid process

2- External auditory canal is alternately opened and closed by pressing the tragus inwards and outwards

📊 Interpretation

Explain the mechanism behind the findings seen in Bing's test in Conductive hearing loss and Sensorineural hearing loss.

Gelle's Test

🔍 Principle

• Test of bone conduction
• Tests the effect of increased air pressure in the ear canal on hearing

🩺 How is it Performed?

1- Vibrating tuning fork is placed on the patient's mastoid process

2- Air pressure in the ear canal is increased using Siegel's speculum

📊 Interpretation

Explain the mechanism behind the findings seen in Gelle's test in Conductive hearing loss and Sensorineural hearing loss.

⚠️ Important Viva Point

• Gelle's test was earlier used to detect Otosclerosis
• It has now been replaced by Tympanometry, a more sensitive test

What is Tympanometry?

⭐ High Yield Rapid Revision Table for Tuning fork tests

🧠 Viva Pearls

• A tuning fork is vibrated by striking it against the examiner's elbow or heel of the hand, never on a hard surface.
• Air conduction tests both conductive and sensorineural pathways.
• Bone conduction tests only the sensorineural pathway.
• Normally, air conduction is louder and longer than bone conduction.
• Rinne negative is seen in conductive hearing loss.
• False negative Rinne is seen in severe unilateral sensorineural hearing loss.
• False negative Rinne is avoided by masking the non-test ear with Bárány's noise box.
• Weber's test determines the side and type of hearing loss, but not the degree.
• Weber's test is lateralized to the poorer ear in conductive hearing loss and to the better ear in sensorineural hearing loss.
• Weber's test is more sensitive than Rinne's test.
• Schwabach's test is lengthened in conductive hearing loss.
• ABC test is also known as Modified Schwabach's test.
• ABC test is more sensitive than Schwabach's test.
• Bing's test is negative in conductive hearing loss.
• Gelle's test is negative in otosclerosis and has been replaced by tympanometry.

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