The Misophonia Consensus Definition
Misophonia is a perceptual disorder that is gaining increased awareness across the
fields of neuroscience, psychiatry, behavioral psychology, and audiology. However,
conclusions as to the underlying etiology and effective management of misophonia suffer
from inconsistent definitions of this disorder in the literature. For instance, some
authors define misophonia as “hatred of sound” resulting in anger,[1] while others consider it to be a reaction to patterns of sound in certain settings.[2] To clarify the definition of this disorder for research and clinical purposes, the
Misophonia Research Fund, an organization supported by The REAM Foundation and in
partnership with the Milken Institute's Center for Strategic Philanthropy, invited
a panel of 15 professionals with specialties in the fields of neuroscience, psychology,
neuropsychology, behavioral psychology, psychiatry, and audiology to develop a consensus
definition of misophonia.[3] Consensus was achieved using a modified Delphi method, which consisted of four rounds
of voting on misophonia-related statements drawn from 68 references in the literature.
Eighty percent agreement among the consensus team was required for the inclusion of
identifiers and descriptors in the definition. The general description of the consensus
definition is included below:
-
Misophonia is a disorder of decreased tolerance to specific sounds or stimuli associated
with such sounds. These stimuli, known as “triggers,” are experienced as unpleasant
or distressing and tend to evoke strong negative emotional, physiological, and behavioral
responses that are not seen in most other people. Misophonic responses do not seem
to be elicited by the loudness of auditory stimuli, but rather by the specific pattern
or meaning to an individual. Trigger stimuli are often repetitive and primarily, but
not exclusively, include stimuli generated by another individual, especially those
produced by the human body. Once a trigger stimulus is detected, individuals with
misophonia may have difficulty distracting themselves from the stimulus and may experience
suffering, distress, and/or impairment in social, occupational, or academic functioning.
The expression of misophonic symptoms varies, as does the severity, which ranges from
mild to severe impairments. Some individuals with misophonia are aware that their
reactions to misophonic trigger stimuli are disproportionate to the circumstances.
Misophonia symptoms are typically first observed in childhood or early adolescence.[3]
Notably, the consensus definition characterizes misophonia as a sound tolerance disorder
in which distinct sounds and/or related sensory input (such as visual imagery) elicit
strong negative emotional, physiological, and behavioral reactions not typically observed
in the general population. This designation differs from the opinion of other experts,
who have stated that misophonia should be classified as a psychiatric disorder, with
diagnostic criteria as such.[1]
[4]
[5] According to the consensus definition, sensory input that evokes atypical negative
responses to sound is termed a “trigger” and is usually generated by another entity
(e.g., a family member), specifically but not limited to the human body (e.g., chewing
versus mechanical sounds). Triggers may initiate intense emotional responses of distress
and subsequent difficulty functioning in everyday life,[6] with such responses lying along a spectrum of severity. Please refer to Swedo et
al,[3] for the complete consensus definition.
This expert definition clarifies several points concerning triggers, associated symptomatology,
and resulting behavioral impairments in individuals with misophonia, as well as emphasizes
the importance of differential diagnosis from similar pathologies (e.g., obsessive,
compulsive-related disorders and hyperacusis). For instance, misophonic responses
may be triggered by auditory inputs and other sensory stimuli present concurrent with
the auditory event. These emotional responses can include many different manifestations,
such as anger, irritation, and disgust.[5] Responses may also be moderated by external factors or context, including the environment
in which the trigger is presented, the patient's relationship with the source of the
trigger, and the sense of control over the aversive stimulus.[7]
[8] Finally, it is important to consider misophonia in relation to comparable disorders,
particularly for therapeutic intervention purposes. Patterns of psychiatric disorders
across a varied range have been found to be highly comorbid with misophonia.[9] The most reported have been mood disorders, such as anxiety and depression.[5]
[6]
[9] These conditions may require medication and/or specific behavioral therapy that
is outside of the audiologist's scope of practice. Within the audiologist's scope
of practice, it is critical that misophonia be differentially diagnosed from the auditory
disorders of hearing loss, tinnitus, recruitment, phonophobia, and, most of all, hyperacusis.[2]
[10] For example, the general description of the Misophonia Consensus Definition could
also characterize hyperacusis, as both are sound tolerance disorders and involve an
intense emotional, behavioral, and physiologic response to sound. Intervention options
for sound tolerance disorders include cognitive behavioral therapy, sound therapy,
and tinnitus retraining therapy.[2]
[11] Clearly, diagnosis and management of misophonia requires a multidisciplinary approach
in which psychiatrists, psychologists, and audiologists come together. However, little
guidance is provided in the literature regarding the audiological diagnostic criteria
for misophonia.
Diagnosing Misophonia as an Audiologist
The consensus definition states that neither misophonia's presence nor severity appear
related to the patient's pure-tone sensitivity, although it is unclear what bearing
hearing loss may have on this percept.[12] While tinnitus is a very different percept from misophonia, that is, a phantom “ringing”
in the ears, significant comorbidity exists between the two pathologies,[2] especially as tinnitus severity increases.[12] Similarly, as previously stated, hyperacusis appears to be highly comorbid with
misophonia.[2]
[12] While the consensus definition does not explicitly clarify the difference between
hyperacusis and misophonia, hyperacusis has been described as an individual experiencing
“physical discomfort or pain” in response to sound levels typically tolerable for
much of the population.[11]
[13]
[14] Misophonia is considered to consist of an intense emotional response to specific
sounds, regardless of intensity level.[3]
[11]
[15] For example, an individual with hyperacusis might react negatively to any sound presented above a set intensity level, while an individual with misophonia
might respond negatively to distinct types of sounds at any intensity. However, it has been suggested that four subtypes
of hyperacusis exist: loudness, annoyance, fear, and pain.[10]
[16] According to this categorization, misophonia could fall into the subtypes of annoyance
or possibly fear, as these emotions are commonly seen in misophonics.[10]
[11]
[16] Salvi and colleagues[16] state that the distinguishing point of difference between these two disorders is
loudness intolerance and that misophonia may be an instance of annoyance and fear
hyperacusis without the loudness component. In considering these definitions, it appears
that if hyperacusis is present, misophonia may then be classified as annoyance and/or
fear hyperacusis. If hyperacusis is not present, misophonia may be a unique diagnosis.
Due to the similarities between these sound intolerance disorders, there is a significant
need for research in the field to determine whether these two conditions are unique
or related subtypes.
Such comorbidities make it very difficult for audiologists to disentangle and identify
misophonia as a clinical diagnosis. While the recent consensus definition does not
recommend clinical measures that may be useful for audiologists in misophonia assessment,
research has indicated that various behavioral and audiometric tools may be sensitive
to this disorder. The following discussion highlights current clinical measures, from
general to specific, that are sensitive to misophonia and will also detect comorbid
audiological disorders such as tinnitus and hyperacusis ([Fig. 1]). This model further identifies behavioral and physiologic measures suggested by
the literature to be sensitive to misophonia (highlighted in yellow) but which still
require rigorous research to determine diagnostic efficacy. For a review of an exhaustive
and exemplary audiological misophonia test battery, please see Pellicori.[17]
Fig. 1 A proposed model for current measures in misophonic assessment that may be used in
the audiology clinic, in addition to standard audiological assessment. The model begins
with general sound tolerance assessment and moves to specific assessment of misophonic
systems. The areas highlighted in yellow demonstrate possible clinical measures that
may be sensitive to misophonia but require additional research.
As in any audiological appointment, a case history is essential. This is where the
clinician may first observe specific patient complaints regarding sound tolerance
and gain insight into the etiology of sound tolerance disorders (e.g., noise exposure,
hearing loss, etc.). Detection of tinnitus, hyperacusis, and misophonia begins with
the patient's self-report. Next, questionnaires ranging from the evaluation of overall
sound tolerance to specific misophonic symptomatology are critical. The Sound Tolerance
Interview and Questionnaire Instrument (STIQI[18]) was developed to obtain information on the patient's sound tolerance that may predict
success for amplification, but scored questions focus on both aided and unaided conditions
and include queries that touch on sound intensity, sound triggers, characteristics
of triggers, and tinnitus. Thus, this questionnaire may be useful in determining sound
tolerance in the domains of hyperacusis, misophonia, and tinnitus for both patients
with hearing loss and hearing thresholds less than or equal to 20 dB HL. Another example
is the Sound Sensitivity Symptoms Questionnaire[19] which consists of questions on emotions and physical sensations elicited by sound.
Following a sound tolerance report, the patient should also complete a tinnitus questionnaire,
such as the Tinnitus Handicap Inventory (THI)[20] or the Tinnitus Functional Index (TFI).[21] A tinnitus questionnaire will establish whether tinnitus is present and comorbid
with misophonia. If so, a separate psychometric tinnitus assessment may be conducted
for the patient if they are participating in a research study or clinical trial,[22]
[23] but this approach is not recommended outside of research practices or for clinical
care.[24] Similarly, a hyperacusis questionnaire will determine if this disorder is present
and comorbid with misophonia, which may inform the intervention approach to focus
on sensitivity to both intensity levels of sound and the type of sound itself. Examples
of hyperacusis assessments include the Modified Khalfa Hyperacusis Questionnaire,[25] the Hyperacusis Impact Questionnaire,[19] and the Inventory of Hyperacusis Symptoms.[26] Finally, symptoms specific to misophonia may be assessed via the Amsterdam Misophonia
Scale,[1] the Duke Misophonia Questionnaire,[27] or the Misophonia Questionnaire,[28] to name a few. Clearly, there are a plethora of surveys that may be implemented
to ascertain whether misophonia and comorbid disorders are present, with only a few
examples listed. Guidelines presented in Schröder et al[1] and Dozier et al[4] for misophonia diagnostic criteria may prove helpful, but at present it is appropriate
for the clinician to use their judgement in building a battery of clinical questionnaires.[17] A suggestion from the author is to ensure that the chosen instrument has been psychometrically
evaluated and validated (all presented examples are validated excluding the STIQI).
Furthermore, it should be noted that the proposed model of multiple questionnaires
ranging from general sound tolerance to misophonia allows the clinician to obtain
a holistic picture of the patient that will aid in intervention while also providing
converging evidence that will point to symptomatology unique to misophonia. At this
point, if misophonia is indicated, a referral to a psychiatrist and psychologist is
warranted. These professionals will assess whether there are comorbid psychiatric
disorders and determine whether medical intervention, as well as behavioral, is required.
While not clinically standardized, some audiometric measures may provide behavioral
indicators of sound tolerance disorders, especially in patients with hearing thresholds
less than or equal to 20 dB HL. [Fig. 1] highlights these approaches to illustrate that additional research is needed to
better understand the clinical utility of such measures, whereas questionnaires have
already been validated. For example, there is some evidence that extended high-frequency
pure-tone testing (above 8 kHz) may reveal significantly better thresholds in patients
with misophonia.[17] Similar findings have been observed in adults with hearing thresholds less than
or equal to 20 dB HL and minimal tinnitus. For instance, adults who have THI scores
at 6 or above tend to present with an extended high-frequency pure-tone average (at
10, 12.5, and 16 kHz) of better than 15 dB HL in the worse ear.[29] Therefore, these individuals may experience a heightened awareness of sound as reflected
by extended high-frequency thresholds.[29] Another metric, loudness discomfort levels (LDLs) or uncomfortable loudness levels,[30] may be significantly decreased in both hyperacusis and misophonia.[2]
[17]
[19] In hyperacusis, LDL values may lie between 60 and 85 dB HL, less than the typical
100 dB HL value, while the range is more variable in misophonia.[2]
[31] Thus, LDL measures are useful in indicating whether hyperacusis is also present
and comorbid with misophonia but would not indicate whether these two conditions are
distinct. Another promising behavioral approach specific to misophonia assessment
investigated in one recent study is the determination of trigger threshold. It would
be hypothesized that triggers might have a lower threshold than other stimuli in a
patient with misophonia. Such an approach was implemented by Savard et al[32] using stimuli embedded in background noise at varying signal-to-noise ratios. While
the authors did not find a significant difference between the threshold of trigger
stimuli for participants with low and high misophonic tendencies, participants with
high misophonic tendencies reported increased negative emotions for trigger stimuli
above the threshold. These findings suggest that a modified trigger-threshold method
performed in quiet, using audio-visual stimuli, or presented in various contexts could
provide a useful tool in misophonia assessment. For example, several researchers have
shown that negative emotions for misophonic triggers are decreased when the auditory
trigger is incongruent with visual stimuli (e.g., lip smacking with a ball bouncing)
or the source is unknown.[8]
[8]
[33] Thus, the measurement of trigger threshold may be significantly decreased when the
context is congruent as compared to incongruent. This approach would be based upon
the patient's reported triggers, allowing for personalized testing that cuts across
the variability triggers for this population.[5] Open-source audio–visual databases containing misophonic stimuli are useful for
such research purposes (https://osf.io/3ysfh/
[33]; https://zenodo.org/record/7109069#.Y9QK8lLMLz8
[34])
Finally, there has been an indication from one study that electrophysiology could
serve as a useful objective measure of misophonia in the audiology clinic. Schroder
et al[35] presented participants with an auditory oddball paradigm while recording cortical
auditory evoked potentials (CAEPs). They found that in participants who fit the diagnostic
criteria for the misophonia, the N1 component in response to oddball tones was present
at a significantly reduced amplitude in comparison to the control group. The authors
surmised that this finding reflects a sensory deficit in the automatic processing
of auditory stimuli, as the N1 is thought to represent mechanisms related to early
attention in processing sound.[36] However, to our knowledge, there are no other studies examining CAEP biomarkers
in misophonia, making it unclear whether this finding is specific to misophonia or
related comorbidities.[35] Other studies have also utilized physiologic measures, such as heart rate and galvanic
skin response, to assess whether there exists a heightened autonomic condition during
trigger presentations.[7]
[37] These physiologic assessments may also prove useful clinically.
A Need for Audiological Diagnostic Guidelines
Due to the minimally researched audiological assessment of misophonia, audiology clinics
specializing in misophonia diagnosis have been left to the development of their own
methodology.[12]
[17] Thus, it is evident that there is a need for consensus on the audiological diagnostic
assessment and criteria for misophonia, including guidelines for distinguishing misophonia
and hyperacusis. The current consensus definition of misophonia is an initial step
toward defining the disorder rather than providing clinical guidance on assessment
and treatment. However, as research on misophonia is growing at a rapid pace,[3] it would be helpful to have an evolving consensus definition that is reviewed every
few years to identify appropriate diagnostic criteria, similar to other pathologies
in medicine.[38] At the same time, in order for there to be diagnostic criteria, translational research
focused on the audiological assessment of misophonia must be ongoing. As previously
stated, this disorder has been designated as a sound tolerance disorder, putting it
directly into the scope of practice for audiologists. As such, there is a call for
clinical researchers to evaluate measures that will be sensitive and specific to misophonia.
Such measures may help to inform targeted treatments that are suggested to be successful
in sound tolerance disorders, such as cognitive behavioral therapy, sound therapy,
and tinnitus retraining therapy.[2]
[6] Posttreatment assessment may then indicate whether such treatment has been effective
in altering trigger perception and associated physiologic responses. While the aforementioned
behavioral measures have shown promise, replication and standardization are still
necessary. In addition, objective physiological markers provided by the auditory brainstem
response and cortical auditory evoked potentials remain to be explored. Finally, it
is the opinion of the author that the next necessary step in the audiological diagnosis
of misophonia is to answer the question of differentiation between misophonia and
hyperacusis. Should these sound tolerance disorders be unique or should misophonia
be a subtype of hyperacusis when loudness intolerance is present? Are the underlying
mechanisms similar or distinct[39]? What audiological measures can be used or developed to provide differential diagnosis?
Without translational research conducted by audiologists and auditory neuroscientists,
clinicians will continue to struggle in providing evidence-based practice for this
population.
