Bedside testing of hearing

Timothy C. Hain, MD •Page last modified: May 13, 2018

There are several ways to evaluate hearing at the bedside. We think that in general, these tests are inferior to formal audiometry, and this is greatly preferred when quickly available. Kelly et al (2018), did a systemic review and observed that there was immense variability in the reports of the reliabilty of bedside tests.

Observation:

The first and simplest is to simply correlate understanding with speech input, observing whether the patient answers appropriately to questions when the examiner's voice is soft or loud, or with the head turned away or towards the patient. Patients who appear to miss more than others, may have hearing loss.

Often patients who can't hear themselves, will speak louder. Similarly, persons in rooms with considerable ambient noise may speak at elevated volumes.

Patients who have severe hearing loss may have "deaf speech', which is a characteristic pattern of impaired pronounciation related to loss of aural feedback.

More practically, one can screen hearing at high frequencies very quickly with one's hands or analog watch.

The "rubbed fingers" test is another quick way to test high-frequency hearing. One rubs one's fingers together, and records how far away from the ear the patient can hear. This method fails when patients pretend to hear.

The "ticking watch" test is also a high-frequency test.

Tuning fork

Rinne

The Rinne test is intended to detect unilateral hearing loss. Done with a tuning fork, it compares perception of sounds transmitted through the air to those transmitted through bone, through the mastoid bone behind the ear. A vibrating 512 Hz tuning fork is placed against the mastoid, and the patient is asked to tell you when they can no longer hear the sound. Normal persons, as well as patients with partial sensorineural hearing loss, can hear the fork through the air, after they can no longer hear it through bone. If one can hear bone better than air, this suggests that there is a conductive pattern hearing loss.

Strangely enough, a "positive" Rinne is a normal Rinne, and occurs when air is louder than bone. In conductive hearing loss, the terminology is that the Rinne is negative. So if you are well, you have a "positive" Rinne, and if you have a conductive hearing loss, it is "negative".

We think it is better to just record whether air is better than bone, rather than saying whether it is positive or negative, as this reduces the chance that whoever reads about your Rinne might not know the convention.

Weber

The Weber test is another tuning fork test. Either a 256 or 512 tuning fork is placed in the middle of the forehead or on top of the patient's head. The patient is asked to report in which ear the sound is louder. Normally, it should be equal for both ears.

For patients with conductive hearing loss, they may hear the tuning fork better in the affected ear. In persons with a sensorineural hearing loss, they hear the tuning fork better in the normal ear. Of course, it is hard to predict which ear will hear the tuning fork better when there is a mixed hearing loss.

Some patients have better hearing from bone than normal people do from air (i.e. SCD). These patients act as if they have a conductive hearing loss.

A similar result to the Weber can be produced by having the patient hum. This is the so-called "hum" test. The logic is simlar to the Weber.

 

References:

Kelly EA, Li B2, Adams ME2. Diagnostic Accuracy of Tuning Fork Tests for Hearing Loss: A Systematic Review. Otolaryngol Head Neck Surg. 2018 Apr 1:194599818770405. doi: 10.1177/0194599818770405. [Epub ahead of print]

Page last modified: May 13, 2018