by Paul A. Fagan, AM MD (Honoris Causa) FRCS FRACS; Isobel R. O’Loughlin, BHlthMedSc(Adv) M.ClinAud
Acoustic Shock Syndrome—also referred to as Tonic Tensor Tympani Syndrome—has been described in individuals exposed to sudden, unexpected high-pitched sounds through telephone headsets or similar devices, most commonly in occupational settings such as call centers. These sounds, while typically brief and well below established safety exposure limits, can be painful and startling, often prompting the individual to instinctively remove the headset.
Symptoms reported following such incidents may include immediate tinnitus, which in some cases persists indefinitely, as well as subjective hearing difficulties. Despite these complaints, objective clinical findings are uncommon. Otoscopic examination typically reveals normal ear canals, tympanic membranes, and middle ear spaces.
Audiometric testing—including pure-tone audiometry and speech discrimination—usually yields results within normal limits, as does tympanometry, indicating normal tympanic membrane mobility and middle ear pressure.
Evidence-Based Medicine and Diagnostic Findings
For more than three decades, the principles of evidence-based medicine have been emphasized in medical education.1 While double-blind clinical trials are often considered the gold standard, such evidence is not always available, particularly in complex otologic conditions. In otology, objective assessments such as audiometry and advanced imaging (CT and MRI) play an essential role in diagnosis and treatment evaluation.
Notably, a review of the available literature reveals no objectively documented abnormalities following reported “post-shriek” events. Despite the presence of distressing symptoms, consistent physical or measurable pathology has not been demonstrated.
Review of the Literature
Groothof reported that although these sounds are rarely loud enough to cause direct inner ear hair cell damage, their impact on affected individuals can be substantial and appears closely linked to psychological stress levels.2 Reported effects range from annoyance to an inability to continue working with headsets. Sound levels delivered through headsets typically remain well below legal exposure limits and below the threshold associated with classic acoustic trauma.
Groothof further hypothesized that the tensor tympani muscle reflex could become “reprogrammed” to respond at lower sound levels. According to this hypothesis, a startle response may restrict ossicular movement and, in extreme cases, generate sufficient force to cause oval window disruption and perilymph leakage. However, no objective evidence has been presented to support these proposed mechanisms, and the likelihood of such catastrophic outcomes is considered extremely low.
Patuzzi and colleagues suggested that Acoustic Shock Syndrome represents a psychosomatic condition arising from heightened psychological tension and stress.3 They proposed involvement of the tensor tympani muscle, central auditory hyperexcitability, and pre-existing anxiety or arousal states, while acknowledging that the underlying mechanisms remain unclear.
Similarly, Noreña et al. proposed an integrative model involving multiple assumptions and theoretical pathways, frequently employing conditional language without providing direct scientific evidence.4
Across published studies, proposed explanations for Acoustic Shock Syndrome remain largely theoretical, with no reproducible objective findings to confirm an underlying otologic pathology.
Fournier et al. concluded that the proposed association between middle ear muscle dysfunction and symptoms such as tinnitus, ear pain, and aural fullness has not been definitively established.5 They emphasized that, due to the absence of reliable measures of tensor tympani muscle function in both normal and pathological states, its role remains speculative.
Westcott and colleagues described Tonic Tensor Tympani Syndrome as an anxiety-based condition characterized by a reduced reflex threshold leading to frequent muscle spasm.6,7 Importantly, all patients in their studies were medically cleared of underlying otologic pathology.
The diversity of interpretations is further illustrated by Keidar et al., who proposed that tensor tympani muscle spasm could cause pulsatile tinnitus—an assertion not widely accepted within the otologic community.8,9
The Victorian Section of the Australian Society of Otolaryngology Head and Neck Surgery states that there is currently no evidence of objective or measurable otologic or neurological pathology associated with this syndrome and that it is best approached as a psychological response.10
Conclusion
While Acoustic Shock Syndrome continues to attract attention in the literature, a comprehensive review strongly suggests the absence of detectable physical pathology underlying the reported symptom cluster. The condition appears to occur predominantly in occupational settings involving high stress, and there are no known reports of its occurrence outside the workplace.
Accordingly, it is the authors’ opinion that the symptoms attributed to Acoustic Shock Syndrome do not have a physical pathological basis and are more appropriately understood within a psychological or stress-related framework.
References
1 Tenny S, Varacallo MA. Evidence-based medicine. StatPearls Publishing; 2024.
2 Groothof B. Acoustic shock in call centres. Proceedings of ACOUSTICS 2005.
3 Patuzzi R. Acute aural trauma in users of telephone headsets. Aust N Z J Audiol. 2002.
4 Noreña AJ et al. Trends Hear. 2018;22:2331216518801725.
5 Fournier P et al. Hear Res. 2022;422:108519.
6 Westcott M et al. Noise Health. 2013;15(63):117–128.
7 Westcott M. Acta Oto-Laryngologica. 2006;126:54–58.
8 Keidar E et al. StatPearls Publishing; 2024.
9 Grierson KE et al. Aust J Otolaryngol. 2018;1:27.
10 Australian Society of Otolaryngology Head and Neck Surgery (Victorian Section). 2017.
About the Authors
Isobel O’Loughlin is an audiologist with a background in Health and Medical Science, trained at the University of Adelaide. Her clinical experience spans adult and paediatric hearing healthcare, including diagnostic audiology, hearing rehabilitation, and implantable hearing solutions.
Paul A. Fagan trained in both General Surgery and Otolaryngology and confined his clinical practice for 35 years to Otology and Skull Base Surgery. He is currently Emeritus Professor of Surgery at the University of New South Wales and St Vincent’s Hospital.
