Hyperacusis (from the Greek hyper- (“excessive”) and akousis (“hearing”)), is defined as a reduced tolerance to sound(s) that are perceived as normal to most of the population or were perceived as normal to the person before their onset of hyperacusis (Adams et al., 2020). Symptomatically, hyperacusis is classified into pain hyperacusis and loudness hyperacusis. Hyperacusis is an umbrella term, as it refers not to a single disorder but to a group of related conditions that share sound intolerance as a common feature, while differing in their causes, mechanisms, symptoms, and comorbidities. The subtypes will be discussed in this section, though much research is still needed to define and understand them clearly (see section Research Recommendations and Priorities).
Hyperacusis is not to be confused with hypoacusis, which is characterized by a reduced ability to hear sounds, ranging from mild hearing loss to complete deafness. Hyperacusis is also different from misophonia (or annoyance hyperacusis), an aversive emotional reaction caused by specific sounds (e.g. chewing or breathing), and from phonophobia (or fear hyperacusis), an unwarranted fear of noise. There can be an overlap of different sound sensitivities (Williams et al., 2021; The Hyperacusis and Misophonia Book).
Hyperacusis is not the same as noise sensitivity. Henry et al. (2022) describe noise sensitivity as increased reactivity to sounds that may include general discomfort (annoyance or feeling overwhelmed) due to a perceived noisy environment, regardless of its loudness. Individuals with for example attention deficit and hyperactivity disorders or autism spectrum disorder are sometimes sensitive to noise, but these patients do not always have hyperacusis or an increased perception of loudness (Bourez et al., 2025).
Hyperacusis is a co-morbid condition of neurodevelopmental disorders such as but not limited to autism spectrum disorder (Williams et al., 2021), FOGXG1 syndrome and Williams syndrome (Tyler et al., 2014). It is also a co-morbid condition of myalgic encephalomyelitis/chronic fatigue syndrome (Maeda et al., 2023), Meniere disease and Lyme disease (Pienkowski et al., 2014), following a traumatic brain injury (Dikmen et al., 2010)) - though patients following such an injury might have a sensitivity to noise instead of hyperacusis (Henry et al., 2022) - or temporomandibular disorders (Pienkowski et al., 2014). Like mentioned above, it is possible patients with these disorders have noise sensitivity rather than hyperacusis, and they do not seem prone to setbacks (see more on setbacks later in the article) like individuals with pain and loudness hyperacusis do (Henry et al., 2022).
The cause of hyperacusis is often noise exposure (Tyler et al., 2014), but it can also be caused by a reaction to certain medications (Longenecker et al., 2021; Musumano et al., 2023; Jin et el., 2025) or diseases (Nazeri et al., 2024).
Loudness hyperacusis is a form of hyperacusis in which everyday sounds at moderate intensity are perceived as uncomfortably or abnormally loud compared to how they are heard by most individuals (Tyler et al., 2014). In pain hyperacusis, also called noxacusis (from Latin noxa, meaning “harm,” or “damage” and from Greek akousis = to hear, Liu et al., 2015) or auditory nociception (Flores et al., 2015), everyday sounds cause physical pain (burning, stabbing, throbbing, pinching, ...) in the ears, throat, neck, face, head and elsewhere in the body (Jahn et al., 2025).
Many patients experience other ear-related symptoms. Some of these symptoms are ear fullness, ear tension, a fluttering feeling in the ear and dizziness (Noreña et al., 2018). These symptoms match what is called tensor tympani syndrome. A distortion of sounds (dysacusis) is also frequently experienced by hyperacusis patients. Moreover, the condition is often associated with tinnitus (ringing in the ears; Jacquemin et al., 2022), reactive tinnitus (tinnitus that gets louder during and/or following noise exposure), diplacusis (the same sound being perceived as different pitches between the ears) and hearing loss (Di Stadio et al., 2018).
There is preliminary evidence for a hyperacusis subtype called somatic hyperacusis, where somatic maneuvers (certain movements of the neck or jaw) can influence hyperacusis (Demoen et al., 2023). It is not clear of this occurs in loudness hyperacusis, pain hyperacusis, or both. Some people experience noise-induced seizures, which are called functional audiogenic seizures (Jacquemin et al., 2024). Furthermore, hyperacusis is often comorbid with visual snow (persistent flickering dots), light sensitivity (Ke et al., 2020; Jahn et al., 2025), dysomia (an alteration or distortion of the perception of smell) and balance problems (Ke et al., 2020), migraines (Klein & Schankin, 2021).
Anecdotally, certain patients experience a fluid discharge in their throat. This has not yet been formally defined in the literature. Studies have found a link between tinnitus and visual snow (Renze, 2017; Klein & Schankin, 2021). To our knowledge, however, no studies have established a link between hyperacusis and visual snow, but it has been anecdotally reported by patients, so has a connection between hyperacusis and dysacusis.
An important and under researched characteristic of pain and loudness hyperacusis is the risk of setbacks, which are symptom exacerbations following exposure to trigger sounds which are otherwise harmless for people with a normal sound tolerance and can be quieter than 75 decibels (which is assumed to be the minimum level of noise required for cochlear damage), depending on the individual severity of the patient. These setbacks can last days but sometimes lead to a permanent drop in sound tolerance and worsening of experienced symptoms (Pollard, 2019, and Williams et al., 2021). To our knowledge, such sensitivity to setbacks has not been reported in individuals with noise sensitivity.
Some patients with hyperacusis experience a lower tolerance to digital/electronic audio (Jahn et al., 2025). The prevalence of hyperacusis is unknown, since to date no studies have differentiated between the different subtypes and levels of severity. We do know that up to 93% of patients with hyperacusis report having tinnitus and 13% of tinnitus patients report suffering from hyperacusis (Jacquemin et al., 2022).