Stenger Test

Purpose

The Stenger test is based on the Stenger effect. The purpose of the test is to identify functional or nonorganic hearing loss. It also can be used to estimate threshold in an individual who is demonstrating this type of hearing loss.

The Stenger test can and should be used whenever there is a difference in air-conduction thresholds between ears of 20 dB or greater. It is best to perform the test immediately upon identifying a difference this large between ears. 

Materials

Audiometer with transducers and two channels activated

Procedures

A tone presented from the right earphone is heard in the right ear and a tone presented from the left earphone is heard in the left ear. However, a tone presented from both earphones is heard as a single, fused image that seems to be located somewhere in the head. This phenomenon is called binaural fusion. The image is heard in the middle of the head if the tone has the same sensation level in both ears. This is a midline lateralization.
  1. A 1000 Hz tone presented only to the right ear at 10 dB SL is heard in the right ear
  2. A 1000 Hz tone presented only to the left ear at 20 dB SL is heard in the left ear
  3. If both of these tones are presented simultaneously, then the listener hears one tone in their left ear
The third part of this example illustrates the lateralization of the fused image to the (left) ear where the SL is higher. We could also say that the sound is audible in both ears, but that the patient is only aware of it in the left ear (where the SL is higher), in which case the situation is called the Stenger Effect.

​Interpretation Site of Lesion

If the patient responds to the tone or speech when the Stenger test is performed, then the test outcome is negative. The patient demonstrating that the hearing loss is likely organic. If the patient fails to respond to the tone or speech, then the test outcome is positive. The patient is demonstrating that he or she likely has a functional or exaggerated hearing loss.

For example, imagine that you have a patient who demonstrates a unilateral hearing loss at 1000Hz. Assume that the "truth" in this case is that the patient does have this loss.
  1. The first question is, "Can a Stenger test be performed in this situation?" The answer is "yes" because there is a 50 dB difference between thresholds.
  2. Next, we determine the intensity of the signal to be presented to each ear.
  3. For the right ear - the "better" ear - the signal is presented at 10 dB above threshold, 20 dB HL in this case. For the left ear - the "poorer" ear - the signal is presented at 10 dB below admitted threshold, 50 dB HL in this case
In this case , the patient has a sensation level of 10 dB in the right ear and -10 dB in the left ear. Due to the Stenger effect, the sound is perceived only in the ear with the higher sensation level. The patient perceives the sound in the right ear and responds appropriately, indicating that the sound was heard. This is a negative Stenger test result.

Now, using the same example, assume that the "truth" of the case is that the patient actually has a functional hearing loss in the left ear. The Stenger test is performed in the same manner, but the results are different. In this case, the patient has a sensation level of 10 dB in the right ear and 30 dB in the left ear. Due to the Stenger effect, the sound is heard only in the ear with the higher sensation level, the left ear. However, because the patient is unwilling to admit to hearing the tone in the left ear at such a low sensation level, the patient does not respond to the tone. This is a positive Stenger test result. It alerts the tester that the hearing loss is likely nonorganic or exaggerated.

Management

Works Cited

Gelfand, Stanley A. Essentials of Audiology. Thieme, 2016.
DeRuiter, Mark, and Virginia Ramachandran. Basic Audiometry Learning Manual. Plural Publishing Inc., 2017