As I forward the medical reports of the 16 Plus safaricom employees who were illegally laid off after suffering from Acoustic Shock Syndrome, I see it necessary to give some info about this rare condition that was promoted by Safaricom's cheap headphones . Here is what I have found online by Myriam Westcott, Audiologist Acoustic shock disorder (ASD) is an involuntary response to a sound perceived as traumatic (usually a sudden, unexpected loud sound heard near the ear), which causes a specific and consistent pattern of neurophysiological and psychological symptoms. These include aural pain/fullness, tinnitus, hyperacusis, muffled hearing, vertigo and other unusual symptoms such as numbness or burning sensations around the ear. Typically, people describe acoustic shock as feeling like they have been stabbed or electrocuted in the ear. If symptoms persist, a range of emotional reactions including post traumatic stress disorder, anxiety and depression can develop.
Call centre staff using a telephone headset are vulnerable to ASD because of the increased likelihood of exposure, close to their ear(s), of sudden unexpected loud sounds randomly transmitted via the telephone line. In the early 1990s, co-inciding with the rapid growth of call centres in Australia, increasing numbers of employees were reporting ASD symptoms. A similar pattern was being noticed overseas. As a result, a number of audiologists, scientists and occupational health experts began to research ASD.
A study of ASD symptoms in 103 call centre operators exposed to 123 acoustic incidents is reviewed. The proposed neurophysiological mechanism of ASD is discussed, in particular tonic tensor tympani syndrome (TTTS) and temporomandibular disorder (TMD). An understanding of TTTS provides insight into the neurophysiological basis of tinnitus and hyperacusis escalation, in association with high levels of emotional trauma and anxiety. Audiological assessment, diagnosis, rehabilitation and workplace management of ASD is discussed.
The potential severity and persistence of ASD symptoms have significant clinical and medico-legal implications. With the rapid growth of call centres around the world, professionals providing tinnitus and hyperacusis therapy are increasingly likely to encounter some or all of the cluster of ASD symptoms in their clients.
Introduction
Acoustic shock is an involuntary response to a sound perceived as traumatic (acoustic incident), which causes a specific and consistent pattern of neurophysiological and psychological symptoms (1). The degree of trauma is influenced by the psychological context of the workplace and/or environment where the acoustic incident exposure occurred. Acoustic shock symptoms are usually temporary, but for some the symptoms can be persistent, escalate and result in a permanent disability. The term acoustic shock disorder (ASD) is used to identify this persistent symptom cluster.
An acoustic incident is any sound that is perceived as threatening, usually a sudden/unexpected/loud sound heard near the ear. The sound is rarely loud enough or present for long enough to cause a noise induced hearing loss. Examples include explosions, telephone faults, scream in the ear.
Background
Call centre staff using a telephone headset are vulnerable to ASD because of the increased likelihood of exposure, close to their ear(s), to an acoustic incident randomly transmitted via the telephone line. In the early 1990s, co-inciding with the rapid growth of call centres in Australia, increasing numbers of employees were reporting acoustic shock symptoms (2). A similar pattern was being noticed overseas (3, 4).
In a more general clinical population, any clients who have developed tinnitus and hyperacusis, particularly following exposure to a sudden unexpected loud sound or associated with a highly traumatic experience, may report at least some of these symptoms (5).
ASD symptoms
ASD causes a specific and consistent pattern of neurophysiological and psychological symptoms. Initial symptoms include a severe startle reaction, often with a head and neck jerk, and a shock/trauma reaction with symptoms of disorientation, distress, shakiness, crying, headache, fatigue. A severe ASD can lead to Post Traumatic Stress Disorder (PTSD). Other symptoms can include pain/blockage/pressure/tympanic fluttering in the ear; pain/burning/numbness around the ear/jaw/neck; tinnitus, hyperacusis and phonophobia; mild vertigo and nausea; headache; and subjective muffled/distorted hearing. ASD generally does not result in a hearing loss, although if present it tends not to follow the typical high frequency pattern of a noise induced hearing injury but affects low and mid frequency sensorineural hearing (1, 2).
Typically, people describe acoustic shock as feeling like they have been stabbed or electrocuted in the ear. The symptoms are involuntary, unpleasant and frightening; they can range from mild to severe; and be of short, temporary duration or persistent. If symptoms persist, a range of emotional reactions including trauma, anxiety and depression can develop.
As ASD symptoms are subjective, they are easily misunderstood, misdiagnosed or not believed. An inadequate understanding of the symptoms often exacerbates anxiety, and can lead to confusion and distress. The long term symptoms of severe ASD are consistent with severe hyperacusis, or category 4 according to the Tinnitus Retraining Therapy (TRT) system of classification. Some of the most severe cases of hyperacusis seen in my clinic are those with ASD.