Pseudohypacusis means, literally, a false elevation of thresholds. In pseudohypacusis, intratest and intertest audiometric inconsistencies cannot be explained by medical examinations or a known organic condition (Ventry and Chaiklin, 1965). Authors of literature in this area have called this condition exaggerated hearing loss, nonorganic hearing loss, or functional hearing loss. Exaggerated hearing loss implies intent, but some forms of pseudohypacusis may have subconscious origins (Wolf et al., 1993). The intent of the listener cannot be determined with audiometric measures. Nonorganic hearing loss implies that there is no physical basis for the hearing loss; however, many adults have a false elevation of thresholds added to an existing loss. Some even present with pseudohypacusis and an ear-related medical problem requiring immediate attention (Qui et al., 1998). Functional hearing loss is the only synonym among these terms.

Monetary or psychological gain motivates most pseudohypacusics. Audiologists should be alert for this condition if the referral source is a lawyer, as in a medicolegal case, or an organization documenting hearing for compensation purposes; however, there are cases where the referral source does not provide any warning. There are even cases of persons with normal auditory systems presenting with longstanding false losses that have been misdiagnosed and the individuals inappropriately fitted with hearing aids.

Estimates of the prevalence rate for pseudohypacusis are between 2% and 5%, with higher rates observed in some special populations, such as the military and industrial workers (Rintelmann and Schwann, 1999). Pseudohypacusics show falsely elevated thresholds in one or both ears, the degree of loss ranges from mild to profound, and the type of loss can be sensorineural or mixed (Qui et al., 1998).

Pseudohypacusics usually adopt an internal loudness yardstick that corresponds to the amount of their “hearing loss” (Vaubel, 1976; Gelfand and Silman, 1985). External sounds are compared with this internal yardstick, and pseudohypacusics only respond behaviorally to sounds that exceed this internal value. This is important to know, because modifications to hearing tests that affect loudness perception often have little or no effect on thresholds of audibility in cooperative adults. Many behavioral tests for pseudohypacusis that are used by audiologists are designed to disrupt loudness judgments.

The responsibility of the audiologist in the assessment of persons presenting with psuedohypacusis is to document intertest and intratest inconsistencies and to quantify true thresholds as a function of frequency. Many methods exist for documenting inconsistent results, but few measures exist for quantifying accurately true behavioral thresholds.

When evaluated for intertest and intratest inconsistencies, the basic battery of audiologic tests, administered to nearly everyone entering the clinic, are the ones that will likely identify persons presenting with this condition, given that many pseudohypacusics have nothing in their history that might raise suspicion. The basic battery of tests that is used in the assessment of pseudohypacusis differs somewhat across clinics, but this group of tests often includes pure-tone thresholds, spondee thresholds, and immittance (see tympanometry).

Pure-tone threshold assessment provides several methods for identifying pseudohypacusis. Most clinicians routinely retest the threshold for a 1000 Hz tone as a reliability check. Thresholds on retest are usually within 10 dB of the first test in cooperative persons, whereas pseudohypacusics often show larger threshold differences (Ventry and Chaiklin, 1965). Although this method is not particularly sensitive or specific for the identification of pseudohypacusis, deviations greater than 10 dB can provide a warning to the clinician. In addition to poor reliability, pseudohypacusics do not demonstrate false positive responses (a response when a tone is not presented) (Ventry and Chaiklin, 1965). By contrast, several false positive responses in a single testing session are quite common in persons with tinnitus (Mineau and Schlauch, 1997). Unfortunately, audiometric configuration is not a reliable diagnostic tool for pseudohypacusis (Ventry and Chaiklin, 1965). However, the presence of a flat loss, or equal hearing loss at each audiometric frequency, has been reported as common in several studies (Coles and Mason, 1984; Alpin and Kane, 1985). The absence of shadow responses in asymmetrical losses is a reliable sign of pseudohypacusis (Rintelmann and Schwann, 1999). Shadow responses are thresholds based on the response of the nontest ear when sound is presented to the poorer, test ear. They reflect a limitation in the ability to isolate the two ears during a hearing test when masking noise is not presented to the nontest ear.

Spondee thresholds, a speech threshold for two-syllable words with equal stress on both syllables, are a quick measure that, when combined with pure-tone thresholds, provide one of the most effective tests for identification of pseudohypacusis. Spondee thresholds in cooperative adults usually fall within 10 dB of the average threshold for 500 Hz and 1000 Hz pure tones (PTA) (Carhart and Porter, 1971). Pseudohypacusics usually show larger differences, with the spondee threshold being lower (better) than the PTA (Carhart, 1952). In some instances, this difference may reflect the naïveté of the listener (Frank, 1976), as is often the case in children. In other words, the listener may feign a loss for tones and not understand that speech thresholds are quantifiable, too. However, this finding in most instances is a result of the loudness of speech and tones growing at different rates. Consistent with loudness-related issues, this test is most effective when spondee thresholds are measured using an ascending approach (beginning at a low level) and pure-tone thresholds are measured using a descending approach (beginning at a high level) (Schlauch et al., 1996). This procedure identified 100% of pseudohypacusics, with no incorrect identifications of cooperative test subjects with hearing loss. A more conventional procedure that measured pure-tone thresholds with an ascending approach identified only about 60% of persons with pseudohypacusis.

Immittance measures are also routine tests that can aid in the documentation of persons presenting with pseudohypacusis. Tympanometry and acoustic reflex thresholds are sensitive measures of middle ear status and provide some indication of the integrity of the auditory system up to the superior olivary complex. For severe sensorineural losses, acoustic reflex thresholds are generally 10 dB or more above a person's behavioral threshold (Gelfand, 1994). Thresholds obtained at lower levels suggest pseudohypacusis. Gelfand (1994) has published normative values of reflex thresholds for different degrees of loss.

Numerous special tests were developed for assessing pseudohypacusis during the period immediately following World War II. Many of the tests developed during this time are confrontational, time-consuming, and ineffective when a clinical decision theory analysis is done. An exception to this criticism is a computer implementation of a simple modification to Bekesy audiometry or automated audiometry (Chaiklin, 1990), which still has application when testing the hearing of large groups of persons with a limited number of testers.

The Stenger test is a special test that is quick to administer and, unlike most tests, has the capability of quantifying the actual thresholds of persons presenting with unilateral pseudohypacusis (Kinstler, Phelan, and Lavender, 1972). This test makes use of the finding that when the same sound is presented simultaneously to both ears, the listener only hears the sound in the ear with the loudest percept. This test can be performed with tones or speech, but to be effective, the asymmetry between ears should be 40 dB or more. Manipulation of the sound levels in each ear is effective in identifying psuedohypacusis and quantifying actual behavioral thresholds (Rintelmann and Schwann, 1999).

Otoacoustic emissions (OAEs) (Musiek, Bornstein, and Rintelmann, 1995) and auditory-evoked potentials (Saunders and Lazenby, 1983; Bars et al., 1994; Musiek, Bornstein, and Rintelmann, 1995) are useful physiological measures for evaluating persons with pseudohypacusis. These special tests assess structures in the auditory pathways. OAEs assess the outer hair cells in the cochlea and the conductive pathway leading to the cochlea; these emissions are often absent even with mild hearing losses. However, auditory neuropathy cases, although rare, show that persons can have essentially normal OAEs and a severe hearing loss (Sininger et al., 1995). This possibility and the fact that many adults exaggerate existing losses make interpretation of OAEs in isolation somewhat ambiguous when evaluating pseudohypacusis. Estimation of the auditory brainstem response (ABR) threshold, a type of evoked potential, has been advocated as a useful measure for compensation cases (Bars et al., 1994), but this threshold assessment tool, while accurate in many situations, can yield misleading results in certain hearing-loss configurations (e.g., a rising audiogram) (Glattke, 1993; Bars et al., 1994). ABR threshold, like OAEs, does not assess the entire auditory pathway as do behavioral measures. OAEs (Gorga et al., 1993) and ABR (Hall, 1992) are also ineffective tools for assessing low frequencies, a critical region for consideration in compensation cases. Other evoked potentials, such as middle latency responses and the slow cortical potential, may hold promise, but like the ABR test, they are expensive to administer (Hyde et al., 1986; Musiek, Bornstein, and Rintelmann, 1995).

The ABR threshold and OAEs are important for the complete documentation of intractable cases or persons presenting with severe to profound bilateral losses, but most cases of pseudohypacusis are resolved by a combination of readministering patient instructions, informing the patient that there are inconsistent responses, and making multiple measurements of the audiogram using an ascending approach. The validity of remeasured pure-tone thresholds is evaluated using the PTA-spondee threshold-screening test described earlier. Patients whose thresholds are not resolved using this approach are scheduled for additional testing. Persons with obvious psychological problems are referred for counseling.

See also clinical decision analysis; otoacoustic emissions; pure-tone threshold assessment; suprathreshold speech recognition; tinnitus.