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Review ArticleNeural Mechanisms Involved in Hypersensitive Hearing:Helping Children with ASD Who Are Overly Sensitive to Sounds

Jay R. Lucker1 and Alex Doman2

1Howard University, Washington, DC, USA2Advanced Brain Technologies, Ogden, UT, USA

Correspondence should be addressed to Jay R. Lucker; [email protected]

Received 6 September 2015; Revised 14 November 2015; Accepted 1 December 2015

Academic Editor: Roberto Canitano

Copyright © 2015 J. R. Lucker and A. Doman. This is an open access article distributed under the Creative Commons AttributionLicense, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properlycited.

Professionals working with children diagnosed with autism spectrum disorder (ASD) may find that these children are overlysensitive to sounds. These professionals are often concerned as to why children may have auditory hypersensitivities. This reviewarticle discusses the neural mechanisms identified underlying hypersensitive hearing in people.The authors focus on brain researchto support the idea of the nonclassical auditory pathways being involved in connecting the auditory system with the emotionalsystem of the brain.The authors also discuss brainmechanisms felt to be involved in auditory hypersensitivity.The authors concludewith a discussion of some treatments for hypersensitive hearing. These treatments include desensitization training and the use oflistening therapies such as The Listening Program.

1. Introduction

Professionals working with children who overly react tosounds want to know why the children have hypersensitivehearing. Additionally, parents of these children want to havea better understanding of their children’s problems. Oftenthese children are described as being afraid of such sounds,losing control of their behaviors when hearing such sounds,and even fearing that the sounds may be heard when thereare no such sounds in the listening environment. Typicallythese behaviors are seen in children diagnosed with autismspectrum disorder (ASD).

For many people, the method applied to deal withchildren who have hypersensitive hearing is to avoid thelistening situations or deal with the child at the time thatthe sounds are occurring. Sometimes, people try to preparechildren by saying that such annoying sounds will occur; yet,even with this preparation, many of these children still losecontrol of their behaviors when the actual sounds are heard.Many professionals relate these hypersensitivities in hearingto problems with the children’s auditory systems.

Lucker and Doman [1] and Lucker [2] discussed the factthat auditory hypersensitivity in childrenwithASD ismore ofan emotional based problem than a specific auditory systemproblem. In these publications, the authors state that under-lying auditory hypersensitivity (or oversensitivity to sounds)involves what are called the nonclassical auditory pathwaysand limbic system connections. However, the authors do notgo very far in describing the brain (or neural) mechanismsinvolved other than identifying that there is a connectionbetween the auditory system and the limbic system deepin the temporal lobe of the brain. The present paper is afollow-up to these 2012 and 2013 publications. The presentpaper reviews that what our present research has indicatedmight be underlying neural mechanisms involved in hyper-sensitive hearing. Understanding these neural mechanismswill provide the reader with two important factors. First,understandingwhat is going onwith a child who has auditoryhypersensitivities is a normal neural reaction and, second,identifying what treatments may be appropriate to helpchildren who are overly sensitive deal more successfully withsound so that they do not have over reactions during listening

Hindawi Publishing CorporationAutism Research and TreatmentVolume 2015, Article ID 369035, 8 pageshttp://dx.doi.org/10.1155/2015/369035

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tasks and, possibly, “shut down” so as to avoid listening andresponding to any sounds.

Before beginning the discussion of these various neuralpathways, the reader should have a clearer understanding ofsome of the terms used in this paper. One term is auditoryhypersensitivity. This problem is often identified as a personbeing overly sensitive to sounds. Some professionals havereferred to the oversensitivity to sounds as misophonia.Others [3, 4] have called this phonophobia or fear of sound.Thus, in the present paper, the use of hypersensitivity willinclude oversensitivity to sounds that includes misophoniaand phonophobia. It is hypothesized that the same neuralmechanisms are involved in all these oversensitivities tosound; however, for some children the sensitivity is only tosounds of an intensity above typical tolerance by people (e.g.,greater than 90 dBHL, as 90 dBHL is often identified as a levelof maximum tolerance in people). For other children, theiroversensitivity may be for a variety of sounds, while for somechildren it is for specific sounds.

2. The Classical Auditory Pathway

Two other important terms used in this paper are classicaland nonclassical auditory pathways. Professionals studyinghearing typically learn about the standard or classical audi-tory pathways. These pathways (see Figure 1) start at thecochlea of the inner ear where the cells of hearing, calledhair cells, release neurochemicals which are picked up by theauditory nerve also known as the eighth cranial nerve. Thisnerve can be found in both ears (right and left sides). Theauditory nerve travels transmitting the auditory stimulationto a region on the right and left sides of the brainstemcalled the pons. Specifically, the nerve innervates areas of thecochlear nucleus. Some of the nerve pathways come from thecochlear nucleus project to the same (ipsilateral) side of thebrainstem while others cross to the opposite (contralateral)side.

The next level in the system involves a complex ofneuronal sites called the superior olivary complex. Thisis still in the lower brainstem within the pons. From thesuperior olivary region the nerves travel to the next levelcalled the lateral lemniscus. (This is an important regionwhen we look at the nonclassical pathways.) From the laterallemniscus, the nerves travel to the inferior colliculus in theclassical pathways. The inferior colliculus is at the upperbrainstem level, and projections from this level go to thethalamus at the cortical level. The nerves projecting fromthe medial geniculate bodies project to the auditory cortexwhich is in the temporal lobe of the brain. Then, via a“bridge” connection between the two auditory cortices of theright and left hemispheres of the brain, the corpus callosumconnects these hemispheres so that we can integrate auditoryinformation from each hemisphere.

3. The Nonclassical Auditory Pathway

The previous description was of the classical auditory path-ways. However, by eight years of age, Moller and Rollins [5]

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identified that this classical pathway becomes the dominantpathway by which sound travels so that we can process andcomprehend what we hear. Moller and his associates [5, 6]identified another pathway which was first investigated inthe 1970s which is also an auditory pathway and is mostlyactive in young children.This pathway has been referred to asthe nonclassical auditory pathway (see Figure 2). In typicallydeveloping children, by the age of 8 years this pathwaybecomes suppressed under most listening conditions.

One of the first neural mechanisms identified as beinginvolved in auditory hypersensitivity is this nonclassical path-way.The nonclassical pathway branches off from the classicalpathway at the level of the lateral lemniscus. Nerves travelingfrom the external nucleus of the lateral lemniscus project andreceive stimulation from the reticular formation in the upperbrainstem. The reticular formation is involved in awareness,detection, and attention to sensory stimulation includingsound. The reticular formation then sends neural informa-tion back to this region of the lateral lemniscus involvedwith auditory sensory processing. These neural inputs travelfrom the external nucleus of the lateral lemniscus to regionsof the thalamus but not the medial geniculate bodies whichare involved with the classical auditory pathway. From theseregions of thalamus, not involved with auditory sensoryprocessing, the nerves project to what is called the auditoryassociation cortex, not the primary auditory cortex which isinvolved with the major processing of what we hear. Theseassociation areas include projections to the limbic systemdeep within the temporal lobe of the brain.The limbic system

Autism Research and Treatment 3

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Figure 2: Diagram of the nonclassical auditory pathways showing the relationship between the pathways from the auditory system to the lim-bic system and to the auditory cortex (diagram retrieved from Noise and Health, 2000, http://www.noiseandhealth.org/viewimage.asp?img=NoiseHealth 2000 2 7 49 31742 1.jpg).

is involved with a number of factors including emotionalresponsiveness. One major center is the amygdala which isinvolved with emotional memories. What is also interestingis that projections to the thalamic regions that receive inputfrom the external nucleus of the lateral lemniscus go directlyto the amygdala. Thus, this nonclassical auditory pathwayconnects auditory sensory input with the emotional centers

of the brain and with brainstem levels of awareness andattention to sensory input.

An important finding from the work of Moller andRollins [5] and Møller et al. [6] is that not only does thenonclassical pathway obtain auditory sensory informationbut also it receives stimulation from the somatosensorysystems of the body.These systems are involved in processing


touch and temperature and help process body position inspace. In Moller and Rollins’ research [5], they found thatoverstimulation of touch (sensory processing) in young,typically developing children led to these children becomingoverly (hyper) sensitive to sound. This occurred for youngchildren up to 8 years of age. After that age, overstimulationof touch did not lead to an increase in auditory hypersen-sitivity. However, these were typically developing children.In another study, Møller et al. [6] discussed that childrenwith autism spectrum disorder (ASD) may continue to beoverly sensitive to touch and, thus, to sound because theirnonclassical auditory systems do not become inhibited torespond under normal listening conditions. In an articlepublished by Musiek et al. [7], they write, “Some childrenwith developmental disorders may have emotional learningproblems caused by the brain’s inability to reduce the involve-ment of the non-classical pathway and the amygdala” (p. 6).These children may include those with ASD. These findingssupport the original discussions fromLucker andDoman’s [1]and Lucker’s [2] publications that auditory hypersensitivity islargely an emotional (limbic system) based response to soundand not an auditory system response to sound. Thus, thetreatment for auditory hypersensitivity, based on this factor,would focus upon calming the emotional system duringlistening tasks.

4. From the Limbic System to BehavioralReactions to Sound

4.1. Involvement of the Vagus Nerve. Once sound has beenprocessed by the brain, the brain reacts to the sound. Asnoted from the previous discussions, one of the systems that isinvolved in hypersensitive hearing is the limbic system. Addi-tionally, observing children who show negative behavioralreactions to sounds we see that they tend to react in mannersone can call negative emotional behavioral reactions. Thesenegative emotional behavioral reactions can include what wecall avoidance or “flight” responses (running away, avoiding,or hiding) or striking out against the “world” or a “fight”response. This “flight and fight” responding is automaticbehavior controlled largely by limbic system reactions tostimuli. However, a question arises as to what mechanismsmay be involved in this negative behavioral reactivity. One ofthese mechanisms is through the innervation of an efferentnerve called the vagus nerve or the tenth cranial nerve whichreceives stimulation from the limbic system.

Porges [8] and Porges and Lewis [9] discuss the func-tioning of the vagus nerve in setting up automatic bodilyresponses to sound as part of what Porges calls the “Poly-vagal Theory.” This theory relates automatic or autonomicfunctions in response to incoming stimuli, such as sound.These autonomic functions are regulated through what iscalled the autonomic nervous system orANS. Essentially, thistheory describes how the vagus nerve is innervated throughlimbic system connections. The information transmittedvia the vagus nerve innervates bodily responses to variousemotional states including stress and fear. For example, thevagus nerve innervates the heart and, under stress and fearfulconditions, a person’s heart rate increases. The vagus nerve

also innervates the larynx or vocal foldswhich allowpeople tovocalize and speak. Under stress and fearful conditions, onemay notice how a person’s voice “cracks,” raises in pitch, orbecomes weak. When sound causes people to have negativeemotional reactions (i.e., hypersensitivity), the vagus nervemay become innervated by the limbic system leading toANS reactions of “flight and fight” which are often seen inchildren who overly react to sounds, such as children withASD. Also, these children may “shut down” in listening andstart babbling incoherently.These changes may be affected byvagal nerve innervation.

4.2. Other Reactions Based on Limbic System Innervation.Mazurek et al. [10, 11] discussed their research looking at theeffects of stress (increased negative emotionality) in rats.Theyfound that under stress, these rats were highly oversensitiveto sound (i.e., auditory hypersensitivity). They identified thatthere were negative reactions after hearing these sounds inthese “stressed” rats. The reactions were measured in theirhypothalamus (a brainmechanism part of the limbic system),their pituitary glands, and their adrenal glands (the latter twobeing part of the ANS). This research suggests that childrenwho are hypersensitive to sound may have problems becauseof similar reactions in their hypothalamus, as well as theiramygdala; both areas are identified earlier in this paper aspart of the limbic system. Furthermore, the reactions to thesenontolerated sounds can set off ANS responses as well as thevagal nerve reactions previously discussed.

In the initial study byMazurek et al. [10] discussed above,the stress in their lab rats was produced by exposure toannoying sounds that were not very intense. This could berelated to child’s normal, ANS reactions to sounds which arenot tolerated which lead to infants and very young childrenbeing frightened by these sounds. For children with ASD,their limbic systems may develop negative memories of thesesounds (through the amygdala) and react negatively becauseof ANS innervation as seen with the animal experimentsdiscussed.

5. Other Neural Mechanisms Involved withHypersensitive Hearing

The nonclassical auditory pathways and the limbic systemare important neural mechanisms involved in hypersensi-tive hearing in children, especially those with ASD. How-ever, there has been recent research indicating that someother factors may be involved. One of these other factorsinvolves problems with neural innervation due to abnormalproduction of neurochemicals such as GABA or gamma-aminobutyric acid as well as 5-hydroxytryptamine (5-HT).This problem with neurochemical production may furtherincrease the auditory hypersensitivities in children. What theresearch indicates is that this abnormal production is foundin children with ASD.

5.1. Abnormal Neurochemical Production and Inhibition5.1.1. GABA. Rubenstein and Merzenich [12] identified thatone of the neural mechanisms found in people with auditory


hypersensitivity is a problem with the neurochemical GABA.They discuss how abnormal GABA production has beenfound in children with autism. Furthermore, they explainhowGABAhelps in the inhibitory control of sensory process-ing including auditory sensory processing.

Inhibition relates to functioning in the followingmanner.When we receive incoming sensory stimuli, we can allowthe stimulation to be transmitted from the sensory receptiveorgan (such as the inner ear) to the brain for furtherprocessing. In the brain, there are cells that transmit neu-rochemicals that “block” the transmission of the incomingsensory stimulation. This blocking is called inhibition whichleads to a reduction in responding. Thus, in the case ofnontolerated, annoying sounds, the brain can “block” orreduce the transmission of the incoming auditory sensorystimuli from getting to the receptor centers in the brain. Oneneurochemical that does this blocking is GABA. Rubensteinand Merzenich [12], as well as investigations by otherscited by these authors, have identified that release of GABAin the brain inhibits overreaction to sensory stimulationsuch as sound. Furthermore, they discuss that childrenwith ASD have a reduction in their GABA production.Abnormal GABA production and transmission leads to ahyperreactivity in the neurons of the brain because of thislack of inhibitory responding. Thus, the person’s brain is notappropriately processing sounds, and the body’s reaction tothis may be referred to as overreactivity. This overreactivitycan lead to negative emotional reactions that lead the childwith ASD to fear and dislike sounds they hear. Researchis needed to investigate GABA in children with autismand identify whether hypersensitive hearing may be due toabnormal production of GABA, inappropriate transmissionof this neurochemical, or a combination of both factors.

5.1.2. 5-Hydroxytryptamine (5-HT), Serotonin. Marriage andBarnes [13] identified that another neurochemical involvedin sensory modulation and, thus, sensory processing, is5-HT, also known as serotonin. Based on animal studies,these researchers describe that abnormal functioning of 5-HT caused a heightened startle response to auditory stimuliin animals. This suggested that auditory hypersensitivityin people might be due to abnormal functioning of 5-HT(serotonin). Baguley [14] stated that people with Williamsyndrome, who are typically found to have auditory hyper-sensitivities, also have serotonin abnormalities in their brains.As such, it is possible that children with ASD may also haveabnormal production of 5-HT. Further research is neededto look at 5-HT/serotonin functioning in these children andrelate this to listening and auditory hypersensitivities.

5.2. Sensory Gating. When we consider the neurochemicalfactors contributing to inhibition, we can see that thesefactors may relate to what some people call sensory gating.Some of the behavioral reactions we see in children who arehypersensitive to soundmay involve how the brain “gates” ordeals with sensory information such as sound and, due to thisgating, how the brain sets up behavioral reactions to sound.Gating relates to the regulation of how the brain handlesincoming sensory information. This “gating” deals with two

factors related to sound processing. One is the acceptanceand “passing on” of sound information to higher corticalcenters such as when we listen in conversations, our neuralsensory gating system allows what the speaker is saying tobe passed through the auditory system to higher levels ofauditory processing into the language centers for languageprocessing and on to the cognitive centers where we thinkabout what the speaker is saying. At the same time, theremay be background noises which our sensory gating systemsinhibit so they are not processed beyond a certain low neurallevel. This is often referred to as auditory filtering.

Some children with auditory filtering problems aredescribed as having abnormalities in something called exec-utive functioning or self-regulation. Executive functionsinvolve those regulatory mechanisms in the prefrontal cortexthat send neural messages to other parts of the brain tomanage the processing of information, including what wehear.These abnormalities are deficits in the frontal lobe of thebrain which suggest that children with ASD having auditoryhypersensitivities may have abnormalities in this part of theirbrains.

Orekhova et al. [15] and Mayer et al. [16] discuss thissensory monitoring or gating and state that our reactionsto how we respond to sensory input are strongly relatedby prefrontal cortical activity. Abnormal prefrontal corticalfunctioning can contribute to poor sensory gating and over-reacting to sensory stimuli. Thus, one factor in the frontallobe contributing to why children may react so stronglyto sound (which we call auditory hypersensitivity) is poorexecutive functioning which does not allow their brains toinhibit these negative emotional reactions from occurring.

5.3. Abnormal Functioning in the Frontal Lobe of the Brain.Another group of researchers have investigated what maybe involved with frontal lobe malfunctioning. Gomot et al.[17] looked at the electrophysiological measure called themismatched negativity or theMMNresponsewhich is relatedto functioning in the frontal lobe of the brain and is a responsethat occurs just prior to neural activity related to listeningattention.TheMMN response is a discriminatory response tochanges in auditory stimuli. For example, if two tones of thesame frequency or two monosyllabic words are heard, thereis a relatively low neural response measured by the MMN.Then, if one of the tones or words is changed, the MMNbecomes larger indicating that the brain has discriminatedand identifying the difference.

Gomot et al. [17] found that in children with audi-tory hypersensitivities, the MMN from the left frontal lobewas abnormal compared with children who had normalreactions to high intensity sounds. Thus, one can concludethat children with auditory hypersensitivities may not beable to appropriately discriminate changes in loudness insound so that unexpected changes may lead to negativeemotional reactions. Thus, one other factor that may lead toabnormalities in brain (neural) functioning in children withASD is this abnormal functioning in discriminating sound.Further research is needed looking at the MMN in childrenwith ASD.


6. What May Occur in Children withAuditory Hypersensitivity

Children’s reactions to certain, intolerant sounds may be anatural, negative response which, over time, becomes filteredby the brain mechanisms discussed above. When we thinkabout how parents (and others) react to young children’sresponses to sounds the child cannot tolerate, the reactionsare usually hugging the child, comforting the child throughtouch, and similar physical reactions. As discussed earlier,somatosensory information is integrated with sound in thenonclassical auditory system. In the typically developingchild, these manual touches may be processed as comfortingleading to a reduction in stresswhich then becomes processedthrough the nonclassical auditory system to interpret soundsthat are annoying and intolerant as not being fearful. Thus,the child learns not to fear such sounds and not to be stressedout when hearing or expecting these annoying sounds. Incontrast, it is hypothesized that the child with ASD andauditory hypersensitivities may overreact not only to thesounds that cause the negative behavioral reactions but alsoto somatosensory stimulation, so that when people try tocomfort them as young children, their nonclassical auditorysystems react with further negative responses, and they learnto associate negative emotional reactions to the sounds.Thus,a focus of the treatment for auditory hypersensitivity has tobe to reduce this negative emotional reactivity, reduce thestress, and reduce the “fight or flight” reactions in people withhypersensitive hearing.

7. Treatment for Hypersensitive Hearing

In view of the above discussions, the underlying themeis that hypersensitive hearing involves neural mechanismsthat are related to emotional processing, emotional memory,and emotional reactivity which is considered negative. Thisnegative reactivity can lead to fight/flight responses affectingthe autonomic nervous system and secretion by glandsthroughout the body as well as neural motor responses thatcan lead to a deterioration or loss of vocalizing (vagus nervereactions) as well as behavioral responses of fighting and run-ning away. As such, the underlying factor for treating theseproblems is to focus on the negative emotional reactions.

In order to better understand how one focuses on theemotional responses, one needs to have a basic understandingof behavioral therapies. There are two general approaches tobehavioral therapy. One is called operant conditioning andthe other is called classical conditioning. Operant condition-ing is typically associated with the work of BF Skinner whileclassical conditioning is associated with the work of IvanPavlov. Operant conditioning follows the basic concept thatwhen we are presented with a stimulus (e.g., a sound of highintensity) and there is a response (e.g., the child runningaway), there is a reaction which occurs that reinforces orpunishes the response increasing (reinforcement) or decreas-ing (punishment) the likelihood that the response will occuragain when the same stimulus is presented. The therapist,educator, or parent providing the reinforcement presentsa reaction to the child’s behavior in order to reduce the

running away behavior (punishment) or to reinforce the childlistening to the sound (reinforcement). Classical conditioningworks slightly differently. We present a stimulus (e.g., thesame intense sound) but we teach the child a behavior thatis different from what is called the unconditioned response(in this example, the child running away is the unconditionedresponse). We may teach the child to count how long thesound is present and reinforce this conditioned response.Over time, the expectation is that the child hearing the soundwill just count how long it lasts, but not run away. Whenwe consider retraining or reprogramming children who haveauditory hypersensitivity, we need to think more in linewith classical conditioning for children who are responsiveand can handle such behavioral training. For some children,such as those with ASD, we may need to consider operantconditioning treatments similar in many respects to whatis often used with these children called ABA or appliedbehavioral analysis.

Therapy or training, which can also be called retraining,is to associate the negative sounds with some behavior thatwill lead to a more calming response and, thus, reduce thenegative emotional reactions to the sound. There are twoproposed methods for doing this. One is through a straightbehavioral training program. The other is through the use ofa listening therapy. The following is a discussion of each ofthese approaches.

7.1. Behavioral Training for Sound Desensitization. Theunderlying concept of a behavioral approach is to reconditionthe person’s system so that the emotional memory is changedfrom negative to more neutral and, if possible, positive.Then,if the person is faced with those stimuli which originally “setoff” the negative emotional responses, the person would havea more neutral response. The goal of behavioral training isto desensitize the person to the previously feared sounds.An example of a behavioral approach would be as follows.Consider a person being annoyed by sounds and havingstrong negative emotional reactions to people eating becauseof the sound of crunching food. The person might be taughthow to relax his/her body and feel more calm which wouldlead to a more positive emotional feeling. Then, the personwould engage in the relaxation exercise while hearing foodcrunching first presented at a low volume level for shortperiods of time then having the volume and length of timeincreased. Eventually, the person would start associating thisrelaxed, more positive feeling with the crunching sound andfeel that he/she can control his/her reactions to the sound.

As one can see, this desensitization using a behavioralapproach takes time and a level of involvement on the partof the person that may not be available for many childrenwith ASD. For them, another approach might be moresuccessful.This approachmay be called “in vivo exposure.” Inthis approach, the person who presents with hypersensitivehearing is slowly introduced to the sounds and situationsinvolving the sounds that led to the negative emotionalreactions. This is done in a controlled manner in real life (invivo) situations. For the same example as used above, theperson may be exposed to someone softly crunching foodonce. The volume of crunching and the number of crunches


as well as the length of time having to listen would then besystematically increased until the person is able to sit througha meal with people. The child going through this systematicdesensitization training would be rewarded for success insitting still while the person is hearing the food crunchingsound (an operant conditioning approach).

An example of in vivo exposure is seen in the research ofKoegel et al. [18]. In their research, they used this approachwith a small group of children identified as being on theautism spectrum and found that even one year after training,the children were desensitized to the sounds which theyoriginally feared. Furthermore, generalization of the trainingoccurred so that the children became desensitized to manysounds that were not part of the original training program.

7.2. Use of Listening Therapies. Along with desensitizationtraining (whether a classical conditioning approach or invivo exposure is used) one can use a sound intervention orlistening therapy. A listening therapy is the use of speciallyrecorded music and environmental sounds having nothingnecessarily to do with the sounds to which the person hasnegative emotional reactions.Themusic and recorded soundsare carefully chosen and systematically produced to enhancepositive emotional and calming reactions when listening.This type of training involves a more passive method todesensitize the limbic system and reprogram the emotionalmemory system with the aim of making sounds somethingto which one desires to listen rather than avoid. The listeningmethod described here uses specially recorded instrumentalmusic. The music is acoustically modified to lead the childto react less negatively to sounds and, thus, reduce the child’shypersensitivity.

Although a number of listening methods have beendeveloped, one specific method found beneficial for childrenwith ASD is The Listening Program (TLP). In TLP, a trainedprovider, usually a professional such as an occupational ther-apist or speech-language pathologist, oversees the training.The provider typically establishes the actual protocol basedon the individual child’s needs andmay carry out the trainingin the child’s home or at the child’s school. When using TLP,especially through specially designed air and bone conduc-tion headphones, the sound signal is believed to travel alongboth classical and nonclassical auditory pathways. One ofthe first outcomes that parents, educators, and professionalsoften see in children undergoing TLP training is that thechildren are calmer.This is a good indicator that the listeninghas tapped into the emotional areas of the limbic systemvia the nonclassical auditory pathways. Over the course oftraining, children often are reported to be more attentiveto sounds, better able to detect (discriminate) sounds theyhear, and are more verbally communicative likely becausethey are more open to listening. As the training proceeds, thechild continues to relax and become calmer when listening.It is hypothesized that this is because a reprogramming ofemotionalmemory in the amygdala is occurring.The trainingalso helps improve stress regulation so the child no longer hasfight/flight responses to nonthreatening sounds. When thechild then finds him- or herself in real-world situations andhears sounds that may have been frightening or annoying in

the past, the training allows the child to process the soundsin a more neutral manner.

For many children, the use of a program such as TLPis sufficient to reprogram their systems so that sound is nolonger frightening. The child may still react verbally sayingthat he or she does not like such sounds or the situationsin which the sounds occur, but after TLP training, thechild should no longer lose control of his or her behaviorwhen hearing such sounds. Additionally, the child may bemore willing to listen to parents or teachers who can modeldesensitization by saying, “The sound is annoying, so let’smove over here,” or “If we walk more quickly toward [ourgoal], we can get away from having to hear that sound.”

Research using TLP has largely been anecdotal, butthe evidence base is growing as studies continue to beconducted. For example, Gee et al. [19] present a casestudy of a child with ASD who was overly sensitive tosound and completed TLP training. They report that thechild showed a decrease in negative behavioral reactions topreviously “annoying” and feared sounds after completingthis training. A review of other studies and descriptions ofindividual cases can also be found at the Advanced BrainTechnologies website (http://www.advancedbrain.com/).Theresearch has demonstrated that after going through thislistening program, children, adolescents, and adults findtheir abilities to tolerate sounds are improved. Many findlistening to be more pleasurable and positive so that negativeemotional reactions rarely occur.Thus, professionals workingwith children who have ASD and auditory hypersensitivitiesas well as parents of these children might wish to try TLPtraining on an investigative basis focusing on seeing changesin the children’s reactions to sounds in their environment. It isthe expectation of these authors that completing TLP trainingshould lead to reduced negative emotional reactions whenlistening increasing the child’s listening and communicationskills. Since listening is an important part of learning, itis hoped that the improvements in listening will improvelearning for these children as well. Further research is neededcarefully investigating these educational and communicativefactors.

8. Conclusions

The underlying theme throughout this paper is that the pri-mary neural mechanisms in hypersensitive hearing involvenegative emotional reactions to sound via connectionsbetween the auditory system and the limbic system aswell as the limbic system and other parts of the body.Research has demonstrated issues involving the auditorysystem connecting with the limbic system as well as frontallobe involvement that can contribute to negative emotionalreactions. Research has also identified some problems basedon poor neurochemical functioning, specifically GABA andserotonin, which eventually lead to negative emotional reac-tions when listening.

Children with ASD may have negative emotional reac-tions to some sounds (i.e., auditory hypersensitivity) thatcan involve some degree of a fight or flight responses. Thetreatment for these hypersensitive hearing problems is felt to


focus on changing the negative emotional reactions to moreneutral and, hopefully, positive responses. This can be donethrough desensitization training which can be in an activeform of behavioral reconditioning or a holistic form calledin vivo exposure. Additionally, the use of a listening therapy,such as The Listening Program, can lead to more neutral orpositive reactions when listening to these annoying sounds.

The focus of this paper was to help the reader understandthe underlying mechanisms involved in hypersensitive hear-ing and the treatments that can help reprogram the person’smechanisms to be more open to listening. In the end, thefocus is to help the child with ASD be more involved incommunicating with the world around him/her. It is hopedthat professionals and parents will consider these factors andthe treatment recommendations discussed. Future researchshould focus on these factors and their direct relationshipto hypersensitive hearing in children with ASD so that wecan obtain a greater understanding of specific mechanismsinvolved with hypersensitive hearing and the evidence basefor the use of treatments such as desensitization training andlistening therapy.

Conflict of Interests

Alex Doman is the Founder and President of AdvancedBrain Technologies, the developer and distributor of TheListening Program and the listening therapy discussed inthis paper. Dr. Jay R. Lucker is a member of the ScientificAdvisory Board of Advanced Brain Technologies. He is alsoa certified/licensed audiologist and speech-language pathol-ogist specializing in auditory processing disorders providingassessments of children, adolescents, and adults with auditoryprocessing disorders including auditory hypersensitivities.

References

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