Weber Test

Understanding hearing loss

Hearing loss can be broadly categorized into two main types: conductive hearing loss and sensorineural hearing loss. Understanding the differences between these two types is crucial for proper diagnosis and treatment. A comprehensive hearing assessment is essential to determine the specific type and extent of hearing loss.

Conductive hearing loss

Conductive hearing loss occurs when an obstruction or interference in the outer or middle ear prevents sound waves from effectively transmitting to the inner ear. This type of hearing loss can be caused by various factors, such as:

1. Earwax buildup or foreign objects in the external auditory canal
2. Fluid accumulation in the middle ear (otitis media) or middle ear infection
3. Perforated or damaged tympanic membrane (eardrum)
4. Abnormalities or dysfunction of the ossicular chain (the three tiny bones in the middle ear responsible for sound transmission)
5. Otosclerosis (abnormal bone growth around the oval window)
6. Congenital malformations or trauma to the outer or middle ear structures

In conductive hearing loss, the inner ear and auditory nerve are generally functioning normally, but the sound waves are unable to reach the inner ear effectively due to obstruction or interference in the outer or middle ear.

Sensorineural hearing loss

Sensorineural hearing loss occurs when there is damage or dysfunction in the inner ear (cochlea) or the auditory nerve. This type of hearing loss can result from various factors, including:

1. Age-related degeneration (presbycusis)
2. Exposure to loud noises or acoustic trauma
3. Genetic or congenital disorders
4. Certain medications (ototoxic drugs)
5. Head injuries or trauma
6. Viral or bacterial infections affecting the inner ear or auditory nerve
7. Tumors or growths in the inner ear or along the auditory nerve pathway

Sensorineural hearing loss affects the hearing threshold by increasing the minimum volume level at which sounds can be heard.

In sensorineural hearing loss, the sound waves reach the inner ear, but the cochlea, or auditory nerve, cannot process and transmit the sound signals effectively to the brain (Tanna et al., 2023). This type of hearing loss is often permanent and may require hearing aids or other assistive devices to improve hearing.

Weber and Rinne test

The Rinne and Weber tests, often performed together during a clinical evaluation, assess the type and degree of hearing loss a patient may be experiencing.

Weber Test

The Weber Test determines whether a patient's hearing loss is conductive or sensorineural. It is performed using a vibrating tuning fork, typically a 512 Hz tuning fork.

The practitioner strikes the tuning fork and places the base of the vibrating fork on the patient's midline, such as the top of the head, the bridge of the nose, or the front teeth. In individuals with normal hearing, the sound from the vibrating tuning fork will be heard equally in both ears. However, in cases of unilateral hearing loss (hearing loss in one ear), the perception of the tuning fork sound will differ.

If the patient has a unilateral sensorineural hearing loss, the tuning fork sound will be heard louder in the affected ear. Conversely, in cases of unilateral conductive hearing loss, the tuning fork sound will be heard louder in the normal ear (Wahid & Attia, 2019).

Rinne test

The Rinne test compares air conduction (sound traveling through the air to the ear canal) and bone conduction (sound transmitted directly to the inner ear through the skull bones). This test helps determine the type of hearing loss present.

The healthcare practitioner strikes a tuning fork and holds it close to the patient’s ear, allowing the patient to hear the sound through air conduction. Once the patient can no longer hear the sound, the practitioner places the base of the vibrating tuning fork on the mastoid bone behind the ear, allowing the patient to hear the sound through bone conduction.

The air-bone gap is the difference between air conduction and bone conduction hearing levels. It is significant in the Rinne test as it helps to identify the type and severity of hearing loss.

In individuals with normal hearing or conductive hearing loss, air conduction is better than bone conduction, resulting in a positive Rinne test (the sound is heard louder through air conduction than bone conduction). However, in cases of sensorineural hearing loss, bone conduction is better than air conduction, resulting in a negative Rinne test (the sound is heard louder through bone conduction than air conduction) (Kong & Fowler, 2019).

How to conduct the Weber Test

The Weber test is a valuable clinical examination used to assess the type and degree of hearing loss. Here is a concise, step-by-step guide for healthcare practitioners on how to perform the Weber Test:

1. Explain the procedure to the patient and ensure they are comfortable.
2. Strike a tuning fork to produce a clear tone.
3. Place the base of the tuning fork on the midline of the patient's forehead.
4. Ask the patient where they hear the sound: in the left ear, the right ear, or both equally.
5. Before performing the Weber test, use an otoscope to check for any obstructions in the ear canal.
6. Interpret the results based on the patient's response.

References

Kong, E. L., & Fowler, J. B. (2019). Rinne test. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK431071/

Tanna, R. J., Lin, J. W., & De Jesus, O. (2023, August 23). Sensorineural hearing loss. PubMed; StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK565860/

Wahid, N. W. B., & Attia, M. (2019, February 19). Weber test. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK526135/