This was a very well conducted and productive interview, thank you, Hazel. In my opinion, it further highlights the importance of locking down a widespread clinically agreed description of what hyperacusis actually is. There are still some subsets that are getting mixed-up and confused amongst one another and I find it staggering that there's still not a definitive clinical representation that's agreed upon worldwide. I think "pain hyperacusis" should be called noxacusis because it's very specific to pain being induced in the ears by sound as well as a lowered loudness threshold. There are clear physiological implications to this as told by Brian and I believe it should be treated as a condition in its own right.
I'm going to pre-warn you that this post is going to be a really long one, but here goes:
The various overlaps between pain hyperacusis, loudness hyperacusis, annoyance hyperacusis, and fear hyperacusis doesn't help matters. If a clinician is not supremely knowledgeable about this condition then their patients are potentially in for a very rough ride. For example, if an audiologist treats their patients as if they all have loudness hyperacusis then people with pain hyperacusis are liable to experience unnecessary setbacks and have a bad clinical experience. There should be more of an individualised approach to helping people, but I don't believe there currently is. I think it's a very fragmented space within healthcare at the moment.
The reason I think the distinction between noxacusis and the other forms of hyperacusis needs to be made clearer is because of the psychological impact the other forms can have on people. Particularly the potential for one to develop a psychological aversion to "all sound" in people with both fear hyperacusis (phonophobia) and tinnitus.
There was a study done recently in Manchester that showed that the overuse of earplugs can actually induce tinnitus and lower the auditory threshold by 6 dB over a matter of days. I found it interesting how some of the study participants described the tinnitus sound that emerged, as well. There was quite a variation from train whistle sounds, to tones, hissing, clicking, creaking, etc. I'll post an excerpt from it below and post a link to the study itself underneath.
Abstract
The occurrence of tinnitus is associated with hearing loss and neuroplastic changes in the brain, but disentangling correlation and causation have remained difficult in both human and animal studies. Here we use earplugs to cause a period of monaural deprivation to induce a temporary, fully reversible tinnitus sensation, to test whether differences in subcortical changes in neural response gain, as reflected through changes in acoustic reflex thresholds (ARTs), could explain the occurrence of tinnitus.
Forty-four subjects with normal hearing wore an earplug in one ear for either 4 (n = 27) or 7 days (n = 17). Thirty subjects reported tinnitus at the end of the deprivation period. ARTs were measured before the earplug period and immediately after taking the earplug out. At the end of the earplug period, ARTs in the plugged ear were decreased by 5.9 ± 1.1 dB in the tinnitus-positive group, and by 6.3 ± 1.1 dB in the tinnitus-negative group. In the control ear, ARTs were increased by 1.3 ± 0.8 dB in the tinnitus-positive group, and by 1.6 ± 2.0 dB in the tinnitus-negative group. There were no significant differences between the groups with 4 and 7 days of auditory deprivation.
Our results suggest that either the subcortical neurophysiological changes underlying the ART reductions might not be related to the occurrence of tinnitus, or that they might be a necessary component of the generation of tinnitus, but with additional changes at a higher level of auditory processing required to give rise to tinnitus. This article is part of a Special Issue entitled: Hearing Loss, Tinnitus, Hyperacusis, Central Gain.
https://www.sciencedirect.com/science/article/pii/S030645221930168X?via=ihub
There is a site in particular (I'll link below) that I believe sheds a bit more light as to what overprotecting and under protecting is. I think this is particularly important as we already know what a minefield this topic can be.
I'll paste some of the content and add the link below:
Earplug Use
The proper use of hearing protection is not well defined for someone with hyperacusis. If you do not use hearing protection, you run the risk of setbacks or social isolation. If you use hearing protection too often, you run the risk of lowering tolerances further or hindering recovery. Anxiety that often accompanies protection behavior may enhance hyperacusis symptoms as it heightens loudness and pain sensations to a degree. Earplug use is a complex, individual decision that needs to be made with careful consideration of the risks of overprotection. In general, it is more natural for someone with hyperacusis to wear earplugs more often than is necessary which is why emphasis is usually placed on reducing protection.
Overprotection
The overuse of hearing protection is almost universally discouraged based on evidence that it will lower loudness thresholds over time. Risks of overprotection include increased auditory gain, anxiety-induced hypersensitivity, and reinforcement of negative associations with sound. Positive results from studies of Sound Therapy & Counseling reinforce the notion that overprotection can prevent people from building sound tolerance. These treatments emphasize a gradual increase in sound exposure rather than sound isolation. It is often recommended that those with hyperacusis walk the fine line between setbacks and overprotection rather than follow a course of isolation and hypervigilance. Practically applying this guideline is not always straightforward.
Underprotection
Increased sound exposure can lead to setbacks. A setback is a sudden drop in sound tolerance as opposed to the gradual reduction in sound tolerance that occurs during overprotection. Setbacks are expected during recovery however they are an under-researched aspect of hyperacusis. Setbacks lasting several days are common. Setbacks lasting weeks, months, or years occur less often but can be deeply discouraging. Anecdotally, it seems setback duration and setback severity reduce to a degree in time. Setback duration and severity also seem to be correlated with hyperacusis severity. While there are over 2200 posts on hyperacusis setbacks in the patient forum on chat-hyperacusis.net, no academic papers could be found using a pubmed search. Some clinicians will inform the patient that sound levels below 85 dB (equivalent to noise from heavy traffic) are safe as they are unlikely to cause long-term hearing loss. While this is comforting and good to know, the relevance to setbacks is unclear as long-term hearing loss (often outer hair cell loss) is not suspected to be related to hyperacusis setbacks. Sound levels that trigger setbacks may be dependent on baseline LDLs and the particular subtype of hyperacusis (pain or loudness). There is a glaring need for research into setbacks to assess the consequences of underprotection. Setback thresholds, duration, severity, and frequency should be studied in relation to long-term recovery. Only then should maximum "safe" sound levels be defined.
Asymmetrical Protection
There are cases of hyperacusis that affect one ear more than the other. This quickly leads to the question, "What happens if I only protect my bad ear?" There is limited research on this topic. Studies suggest that auditory gain in the protected ear will increase. If the asymmetrical symptoms are related to a contraction of the acoustic reflex, sound into the unprotected ear can trigger the reflex in the protected ear as well, which would limit the effectiveness of protection. There are similar concerns about asymmetrical protection as there are for general overprotection.
https://hyperacusisfocus.org/research/earplug-use-2/
I think Richard Tyler does a good job of explaining the subsets of hyperacusis and the various problems that can arise whilst trying to treat them. Again, I'll paste some of his content below and I'll put bits in bold that stand out to me.
Richard S. Tyler, PhD, professor of communication sciences and disorders and of otolaryngology at the University of Iowa, describes four categories of hyperacusis: loudness, annoyance, fear, and pain. While he sees all of these subtypes intersecting in the clinic, epidemiological data on hyperacusis are lacking, "so it's hard to know how much overlap actually occurs," he said.
In loudness hyperacusis, moderately intense sounds are perceived as too loud, while annoyance hyperacusis is "a negative emotional reaction to sounds," Dr. Tyler said.
Fear hyperacusis is a negative response to sounds that may cause patients to avoid social situations or feel anxiety in anticipation of hearing these sounds. Pain is also associated with hyperacusis and may include a stabbing sensation at much lower sound levels than would typically prompt pain.
One type of hyperacusis may lead to another, Dr. Tyler said.
"If you experience loudness hyperacusis, emotional consequences may follow, leading to stress and annoyance, which eventually lead to fear of going to events and socializing," he said. "Pain is a little more complicated because it consists of both a fundamental attribute and an emotional consequence."
People with hyperacusis have increased activity in the tensor tympani muscle in response to some sounds, which can tighten the eardrum and lead to pain, said Dr. Melcher, citing research published in Noise & Health(2013;15[63]:117-128).
"We often see pain in our patients," said Fan-Gang Zeng, PhD, professor of otolaryngology in the School of Medicine and director of the Center for Hearing Research at the University of California, Irvine, and chair of The Hearing Journal's Editorial Advisory Board.
"When the sound reaches a certain level, patients will say, 'It's not just the loudness that's bothering me; it's the pinging sensation or tingling.'"
ONE IN 50,000
Hyperacusis is rare, affecting one in 50,000 people, according to the American Academy of Otolaryngology–Head and Neck Surgery (AAO-HNS).
Prevalence rates were between eight and nine percent in a 2002 mail and Internet survey (Int J Audiol 2002;41[8]:545-554), while other researchers have estimated a prevalence of two percent in the adult population. (Baguley DM, McFerran DJ. Hyperacusis and disorders of loudness perception. In: Møller A, Langguth B, De Ridder D, Kleinjung T, eds. Textbook of Tinnitus. New York, NY: Springer; 2011:13-24.)
Hyperacusis appears to result from reduced nerve input and response to sound, Dr. Zeng said. As a result, the brain has no choice but to increase gain, causing over-amplification in its attempt to compensate.
"The brain is dynamically changing in response to the environment and the pathological conditions in the ear," he said.
With the loudness form of the condition, "there is likely greater activity on individual hearing nerve fibers and across more hearing nerve fibers than would occur in the normal ear without hyperacusis," Dr. Tyler said.
If patients experience annoyance or fear, then the many corresponding emotional centers of the brain must also be activated. These networks are active for different types of stressors, not just hyperacusis, he noted.
Hyperacusis is frequently associated with noise exposure and tinnitus (see box), but many patients have apparently normal hearing thresholds, Dr. Tyler said.
Some patients with hyperacusis have high-frequency hearing loss, but the loss is not always reflected by the audiogram, Dr. Zeng said. Patients with hyperacusis are often bothered by sounds at all frequencies, provided they reach a certain decibel level, he added.
Conditions that are associated with hyperacusis include Bell's palsy, Lyme disease, depression, and autism, among others, according to the American Speech–Language–Hearing Association (ASHA). In addition to noise exposure, causes may include physical trauma to the head or viral infection of the inner ear.
Audiologists can assess loudness hyperacusis by measuring loudness growth or loudness discomfort levels with pure tones, said Dr. Tyler, although some studies from the hearing healthcare literature use actual recordings of environmental sounds.
Dr. Zeng finds that exposing patients to a conversational sound level of 60 to 70 dB and asking them to indicate if this level is too loud helps determine if they have hyperacusis, he said.
Questionnaires are valuable for determining annoyance and fear components of the disorder, Dr. Tyler said. Generally, such assessments consist of subjective responses.
"If patients say they're afraid to go to work or the cafeteria because it's too noisy, then, clinically speaking, you know they have fear hyperacusis," he said. Audiologists also need to ask patients if they are experiencing any associated ear pain, he added.
LOWERING THE VOLUME
Counseling and sound therapy are two common approaches to managing hyperacusis. They can help retrain the brain and reduce the physiological activity that leads to the condition, Dr. Melcher said.
Many counseling techniques are now available, Dr. Tyler said. For example, hyperacusis activities treatment includes components of cognitive behavior therapy, helping patients adjust their perceptions and providing techniques to improve concentration.
"And, of course, when people change their feelings and impressions about a condition, something in the brain changes as well," Dr. Tyler said.
Sound therapy can be very effective for hyperacusis, he said. Data indicate that exposure to continuous low-level broadband noise can improve objective measures of loudness hyperacusis ( Semin Hear 2002;23[1]:21-34; Acta Otolaryngol 2005;125[5]:503-509).
While continuous broadband noise has been used to treat tinnitus and is now advocated for hyperacusis therapy, "white noise is not very effective compared with modulated dynamic sounds," Dr. Zeng said.
Another approach, successive approximation using high-level broadband noise, may be effective, said Dr. Tyler, adding that the therapy was recommended by the late Jack A. Vernon, PhD, cofounder of the American Tinnitus Association (ATA).
This form of sound therapy involves noise exposure that increases in loudness and duration over time. (Tyler RS, Noble W, Coelho C, Haskell G, Bardia A. Tinnitus and hyperacusis. In: Katz J, Medwetsky L, Burkard R, Hood L, eds. Handbook of Clinical Audiology. 6th ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2009:726-742.)
UNCOVERING THE CAUSE
While therapies for hyperacusis are available, treatment codes are not, so reimbursement for audiologists is challenging, Dr. Tyler said.
Once more effective treatments are established, the healthcare system will likely provide better reimbursement, Dr. Zeng said. The effectiveness of hyperacusis therapy needs to be comparable to that of other reimbursable audiological treatments, such as cochlear implants, he said.
"First, you have to have the research, with good quality-of-life outcomes."
Additional clinical trials are essential, Dr. Tyler said. Investigators need a better understanding of how to measure loudness hyperacusis while taking emotional influences into account. Studies also must evaluate the use of sound therapy and more specific counseling procedures for hyperacusis treatment.
In addition, further research needs to investigate the causes of hyperacusis, the physiological changes that occur in the inner ear and nerves, and the brain's response, in addition to how sound can affect pain receptors, Dr. Zeng said.
"We really need some kind of biomarker to objectively measure the condition," he said. "It's almost impossible to create effective treatments until we know what causes the condition."
In the case of Rob, the musician from Georgia, an audiologist at Emory University recommended Tinnitus Retraining Therapy (TRT) as a treatment for hyperacusis. However, Rob found the presentation of sound in TRT too difficult to tolerate, so he opted for customized pink noise.
His pink noise program used open-air headphones and started with a high-end frequency presentation of 3,000 Hz. He listened to this for eight hours a day at a low volume for three months, gradually increasing the volume during the second and third months. Rob also gradually increased the high-end frequency of the presentation, as well as the amplitude of selected frequency points.
He can now listen to 22,050 Hz. His loudness discomfort levels were originally in the 30- and 40-dB range, and now they're in the 90- and 100-dB range.
Overall, his therapy has taken about three years, and Rob said he believes his sound tolerance can further improve.
"It took me a long time to get there, but it's been very successful," he said.
There's also the interesting aspect of cochlea synaptopathy and it's role in all of this. I found this interesting from the work of Charles Liberman:
Cochlear synaptopathy has been demonstrated in animal models in response to aging, noise exposure, and ototoxic drug exposure (Kujawa and Liberman, 2009; Sergeyenko et al., 2013; Ruan et al., 2014). Remarkably, up to 50% synaptic loss has been observed in the absence of any permanent threshold shift (Kujawa and Liberman, 2009; Sergeyenko et al., 2013). This has led to concern about the effects of syn- aptopathy on human auditory perception that may be "hidden" from the audiogram. Unfortunately, this perceptual impact has proved difficult to study. Although human tempo- ral bone studies confirm that auditory neuronal and synaptic loss occur in humans with age (Makary et al., 2011; Viana et al., 2015), studies of synaptopathy in living humans are complicated by the lack of a reliable non-invasive metric of the cochlear synaptic number and the large degree of mea- surement error associated with self-reported noise exposure. In animal models of synaptopathy, the amplitude of wave I of the auditory brainstem response (ABR) is highly corre- lated with synaptic survival (Kujawa and Liberman, 2009; Lin et al., 2011; Sergeyenko et al., 2013). This makes ABR wave I amplitude a good candidate measure for studying synaptopathy in humans, although care must be taken when interpreting ABR results as wave I amplitude may also be impacted by factors such as electrode impedance, head size and anatomy, sex, and OHC function.
https://asa.scitation.org/doi/pdf/10.1121/1.5132708?class=pdf
The discussion of the auditory gain model of tinnitus and hyperacusis is also something that comes up really frequently, as well as the gating hypothesis. Brian spoke about this at circa 18 minutes into the podcast and I think Will Sedley goes over some of the ideas behind this quite extensively - from his perspective - here (if this sort of stuff interests you then I'd recommend reading through all of it):
https://www.sciencedirect.com/science/article/pii/S0306452219300478?via=ihub
I also agree with Brian, at circa 25 minutes, that reactive tinnitus is not hyperacusis, although, there may well be a lot of overlap which seems inevitable with these conditions. I remember bringing this up about two years ago whilst referencing some hearing related literature (which kind of agrees with what Brian said about researchers accepting the term but not so much people on the clinical side). I remember saying that it seemed to be becoming a more accepted term, academically speaking, and I also remember Michael Leigh vehemently disagreeing with me at the time, but I suppose that's his right to do so.
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