with the pain of a root canal or a broken tooth. Loudness discomfort level (LDL) The threshold of sound at which discomfort is initially experienced; measured in decibels (dB). Setback After a period of some relief from symptoms, discomfort resumes; often resulting from exposure to sound, or, in some cases, ototoxic medications or injuries. Setback prevention is an important focus among those affected. Associated conditions Some conditions that are associated with hyperacusis include: Acoustic shock Adverse drug reaction Anxiety Asperger syndrome Attention deficit hyperactivity disorder Autism spectrum Bell's palsy Depression Endolymphatic hydrops Fetal alcohol spectrum disorder Hypothyroidism Lyme disease Migraine Ménière's disease Temporomandibular joint disorder Trigeminal neuralgia Multiple sclerosis Noise-induced hearing loss Posttraumatic stress disorder Severe head trauma Sjögren syndrome Superior canal dehiscence syndrome (SCDS) Systemic lupus erythematosus (SLE) Tay–Sachs disease Tinnitus Tonic tensor tympani syndrome Visual snow Williams syndrome Causes The most common cause of hyperacusis is overexposure to excessively high decibel (sound pressure) levels. Some affected people acquire hyperacusis suddenly as a result of taking ear sensitizing drugs, Lyme disease, Ménière's disease, head injury, or surgery. Others are born with sound sensitivity, develop superior canal dehiscence syndrome, have had a history of ear infections, or come from a family that has had hearing problems. Bell's palsy can trigger hyperacusis if the associated flaccid paralysis affects the tensor tympani, and stapedius, two small muscles of the middle ear. Paralysis of the stapedius muscle prevents its function in dampening the oscillations of the ossicles, causing sound to be abnormally loud on the affected side. Age may also be a significant factor . Some psychoactive drugs such as LSD, methaqualone, or phencyclidine can cause hyperacusis. An antibiotic, ciprofloxacin, has also been seen to be a cause, known as ciprofloxacin-related hyperacusis. Benzodiazepine withdrawal syndrome is also a possible cause. Audiologists may advise against using hearing protection in normal sound environments, claiming it can cause or worsen hyperacusis. Preliminary research showed that people with hyperacusis can experience an exacerbation of their symptoms when not adequately protecting themselves against loud sounds. An acoustic shock can also occur after exposure to an unexpected moderately loud to loud noise, even if this does not necessarily result in permanent cochlear damage. Neurophysiological mechanisms As one important mechanism, adaptation processes in the auditory brain that influence the dynamic range of neural responses are assumed to be distorted by irregular input from the inner ear. This is mainly caused