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LESSON 136

Pseudohypacusis

Year 2
Spring semester
Diagnostic Audiology
Differential diagnosis and special tests
Duration: 11:28

We explain pseudohypacusis, or nonorganic hearing loss, where measured thresholds do not reflect true hearing. With examples, we cover a mismatch between the SRT and the pure-tone average, the absence of a shadow curve, the Stenger test, and confirmation with OAEs, acoustic reflexes and ABR.

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Hello, and welcome to the AIHEAR Audiology Academy.
In this lesson we will learn to recognize cases where measured thresholds do not reflect true hearing, that is, nonorganic hearing loss.
Step by step, we will look at warning signs, the Stenger test and confirmation with objective tests.
Pseudohypacusis is when a person's test responses show a worse loss than their true hearing level.
There is no outer, middle or inner ear problem to explain the measured loss, or the problem cannot explain a loss this large.
The terms nonorganic hearing loss and functional hearing loss are also used for the same picture.
It is often seen as an exaggeration added on top of a real, organic loss.
The cause may be a conscious expectation of gain, or psychological factors the person is not aware of.
The audiologist's task is not to judge intent but to determine the true hearing level as accurately as possible.
Pseudohypacusis most often comes to mind in assessments where the result will support a report or an official decision.
Compensation claims for workplace noise or insurance processes are typical examples of these situations.
It can also be seen in school-age children; here factors such as stress or a need for attention often play a role.
In some people, the loss is not conscious and appears as a sign of psychological distress.
None of these contexts alone means pseudohypacusis; they only call for extra care.
The first clue often comes before testing: the person follows the conversation easily, yet the audiogram shows a severe loss.
Showy listening behaviors, such as cupping a hand to the ear or leaning in exaggeratedly, may also stand out.
During testing, responses may be delayed, hesitant, and present one time and absent the next at the same level.
Repeating only half of two-syllable words in speech testing is another commonly reported clue.
These observations do not settle anything alone, but they are weighed together with the test findings.
In an organic loss, thresholds usually stay within five decibels on repeat testing; much larger swings are a warning.
A speech recognition threshold, or SRT, clearly better than the pure-tone average is a strong clue.
In a severe unilateral loss, the absence of the expected cross-hearing in unmasked testing, the shadow curve, is also important.
An acoustic reflex threshold equal to or better than the pure-tone threshold the person reports also shows inconsistency.
What these clues share is that the tests do not confirm each other.
According to the cross-check principle, contradictory results call for further assessment.
Let us look at a purely example audiogram; the person reports no hearing at all in the left ear, and testing uses supra-aural earphones.
In this example, the right ear thresholds are normal.
In the left ear, in unmasked testing, there is no response even at the maximum output of the device.
Yet even if the left ear heard nothing, a loud enough sound would reach the right cochlea through the skull and the person would respond.
With supra-aural earphones, interaural attenuation is about 40 to 80 decibels, depending on the person and the frequency.
So the normal right ear should have heard sound presented to the left ear by about 90 dB HL at the latest.
The absence of the expected shadow curve is a strong warning that the reported loss is not real.
In organic losses, the SRT and the pure-tone average usually agree within about ten decibels.
An SRT clearly better than the pure-tone average suggests a nonorganic component.
In this example, the pure-tone average was measured at 60 dB HL.
The SRT, however, is 30 dB HL; the person can repeat words far below the level at which they say they hear pure tones.
One reason is that holding a consistent false threshold is harder for speech than for pure tones.
The Stenger test relies on a simple perceptual principle: a tone of the same frequency is presented to both ears at once.
In this case, the person hears the sound only in the ear where it seems louder.
The sound in the other ear goes unnoticed, even if it is at an audible level.
The test takes advantage of the person responding without knowing in which ear they perceive the sound.
That is why it is useful when a unilateral or clearly asymmetric loss is reported.
First, both ears' thresholds at the same frequency must be known; for the test to work, they usually differ by at least 20 decibels.
A tone about 10 decibels above threshold is presented to the better ear; the person hears it easily and responds.
At the same time, the same tone is added to the poorer ear about 10 decibels below the reported threshold.
We watch whether the person responds.
If the loss is real, the sound in the poorer ear is not heard, the sound in the better ear is perceived, and the person keeps responding.
If the true loss is smaller than reported, the poorer-ear tone seems louder; the person hears it only in that ear and does not respond.
If the person keeps responding, the result is called a negative Stenger, and the reported asymmetry may be real.
If the person stops responding, the result is called a positive Stenger, and it shows a nonorganic component.
A positive result means the poorer ear hears a sound below its reported threshold.
Then, by gradually changing the tone in the poorer ear, the lowest level at which the person stops responding can be found.
This level is called the minimum contralateral interference level, and it gives an approximate estimate of the true threshold.
The Stenger test is most sensitive when a clear difference between the ears is reported; with small asymmetries, it is less reliable.
The test requires an audiometer that can present the same tone on two channels at the same time.
The person is told, as usual, to respond whenever they hear the sound; no extra explanation is given.
The same principle can also be applied with speech; this is called the speech Stenger test.
The Stenger test is quick and easy, but its result is always interpreted together with other tests.
Normal otoacoustic emissions, or OAEs, show that the outer hair cells are working.
In someone reporting a severe cochlear loss, normal OAEs do not fit the report; but they do not rule out neural losses.
Acoustic reflex thresholds are compared with the reported thresholds to check for consistency.
The auditory brainstem response, or ABR, and the auditory steady-state response, or ASSR, estimate thresholds without cooperation.
Especially when a report is required, behavioral thresholds should be supported by an objective method.
Objective tests show an upper limit of true hearing; the true threshold is often close to this estimate or better.
The acoustic reflex appears when sound reaches a level well above the hearing threshold.
In people with normal hearing, reflex thresholds are usually between 70 and 100 dB HL.
If the reflex appears at or below a level where the person says they hear nothing, the reported threshold cannot be real.
Obtaining reflexes at normal levels in an ear reported to have a severe loss also contradicts the report.
However, absent reflexes can also come from middle ear or nerve problems, so they are not proof on their own.
A clinical tip: do not take an accusatory attitude when responses are inconsistent.
Give the instructions again, simply; remind the person to respond whenever they hear even the softest sounds.
Finding the threshold with an ascending approach, starting from silence, can make it harder to hold a false response level.
Repeat the test in a calm tone and clearly document the inconsistencies in the report.
The report states the reliability of behavioral thresholds clearly; inconsistent results are not presented as true thresholds.
Findings are described; for example, inconsistencies suggesting a nonorganic component are noted, with no comment on the person's intent.
Objective tests such as ABR or ASSR are recommended to determine the true threshold.
With children, a supportive talk is held with the family; if needed, referral for medical and mental health support is considered.
Remember: a nonorganic component does not rule out a real hearing loss in the same person.
In pseudohypacusis, measured thresholds are worse than the true hearing level.
Inconsistent retest thresholds, an SRT that does not match the pure-tone average, and an absent shadow curve are the main clues.
In the Stenger test, the person stopping their responses, a positive Stenger, shows a nonorganic component.
The true hearing level is confirmed with objective tests such as OAEs, acoustic reflexes and ABR.
Test yourself: in the Stenger test, when a tone is added to the poorer ear, the person stops responding. What is the result?
The correct answer is B: a positive Stenger.
The person perceives the sound in the poorer ear below their reported threshold; this shows a nonorganic component.
In the next lesson, we will learn about real asymmetric hearing loss and the audiologist's approach when vestibular schwannoma is suspected.
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Prerequisites

LESSON 134 Cochlear or retrocochlear?

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