What is the procedure for performing the Schwabach test?

How to Perform the Schwabach Test

The Schwabach test compares the duration of bone conduction hearing between the patient and examiner by placing a vibrating tuning fork on the mastoid process of each, with the examiner serving as the normal control. 1

Test Procedure

Equipment and Setup

• Use a 512 Hz tuning fork as the standard frequency for bone conduction testing 2
• Apply firm pressure of approximately 2400 g (23.5 N) when placing the tuning fork on the mastoid process, as this force provides optimal sensitivity, specificity, and accuracy 2
• The examiner must have normal hearing to serve as the control reference 1

Step-by-Step Technique

Patient Testing:

• Strike the tuning fork to set it vibrating 3
• Place the base of the vibrating tuning fork firmly on the patient's mastoid process (the bony prominence behind the ear) 1
• Ask the patient to indicate when they can no longer hear the sound 1
• Note the duration or time when the patient stops perceiving the vibration 3

Examiner Comparison:

• Immediately transfer the still-vibrating tuning fork to the examiner's own mastoid process 1
• Determine if the examiner (with normal hearing) can still perceive the sound 1
• Compare the duration of bone conduction between patient and examiner 3, 1

Interpretation

Normal Result (Schwabach Equal):

• Patient and examiner hear the tuning fork for approximately the same duration 1
• Indicates normal bone conduction hearing 3

Schwabach Shortened:

• Patient stops hearing before the examiner 1
• Suggests sensorineural hearing loss (nerve dysfunction) 3
• The perceptive component of hearing is impaired 3

Schwabach Prolonged:

• Patient continues to hear after the examiner stops 1
• Suggests conductive hearing loss 3
• Bone conduction is relatively preserved while air conduction is impaired 3

Critical Technical Considerations

Force Application

• Avoid light pressure (400 g) as it significantly reduces test accuracy 2
• Inconsistent force application is a major source of variability and false results 2
• The precise force of 2400 g allows better reproducibility and meaningful comparison of results 2

Common Pitfalls

• Using the examiner with abnormal hearing invalidates the test as the normal reference is lost 1
• Insufficient vibration of the tuning fork before testing leads to shortened perception times 2
• Transferring the fork too slowly between patient and examiner allows the vibration to decay, making comparison unreliable 1
• Not maintaining consistent pressure throughout the test introduces measurement error 2

Clinical Context

The Schwabach test was extensively studied and popularized by Schwabach in 1885, though earlier descriptions existed by Schmalz (1849), Lucae (1880), and Emerson (1884) 1. While historically important, the test provides an absolute index of the perceptive component of hearing (nerve function) when properly performed 3. Modern alternatives include the cell phone vibration test, which shows substantial concordance with traditional tuning fork tests and can be self-administered 4.