Could a Simple Hearing Test Diagnose Autism?

Big Ear

A recent study published in Autism Research is stirring controversy over reports that a simple hearing test may help with early autism diagnosis. The test is the auditory stapedial reflex (ASR) test which measures how one of the two middle ear muscles called the stapedius contracts in response to loud sounds.  According to the authors of the study an absent reflex would indicate an autism risk factor.

The reflex attenuates sudden loud sound to protect the delicate inner hair cells from damage. Without this sound dampening the auditory system is bombarded by sound which results in a number of behavioral responses such as covering of ears, running from the sound, aggression, and more.  These are characteristically fight/flight behaviors seemingly in response to sound, in this case a stressor. Last year I published an article with Dr. Jay Lucker in Autism Science Digest identifying that in most cases the response is an emotional rather than auditory response that can be trained with music listening therapy and behavioral techniques and is not exclusive to people diagnosed with autism.

If you read the research abstract (link below) you’ll see the investigators are making an argument for absent reflexes as an autism biomarker. My concern is they tested children with autism compared to a smaller group which was “neurotypical” but not other neurodevelopmental disorders which based on my experience would very likely yield the same results… Auditory deficits are a common feature in autism chief among them hypersensitivity to sound in which the brain appears unable to filter out undesirable sound resulting in pain or discomfort.  However this is also true of Sensory Processing Disorder, ADHD, Auditory Processing Disorder, etc.

I’m pleased to see the attention on the auditory system in the autism research field, but caution looking to the ASR as a reliable autism biomarker without further study. What are your thoughts?

Abstract:  Quantification of the Stapedial Reflex Reveals Delayed Responses in Autism Autism Res 2013

Happy 4th of July America!

fireworks

If you are an American like me, then very likely tomorrow will be filled with parades, bbq’s, and fireworks as we honor the adoption of the Declaration of Independence.

Hopefully also like me, you’ll be picking up ear plugs for you and your kids so you can protect your hearing when those spectacularly loud 140-165 dB fireworks start filling our skies in celebration of our freedom.

Our hearing is precious, let’s preserve it so we can enjoy the sweet sounds of liberty for years to come… You with me?

Happy 4th of July America!

 

The ear bones connected to the head bone…

Bone Conduction

Guest Post By: Seth Horowitz, Ph.D., Neuroscientist and author The Universal Sense

When we think about hearing (if we think about it at all), we tend to focus on its ephemerality.  Sound comes from vibrating air molecules moving so gently that we can’t feel them (unless we’re standing dangerously close to a speaker), inducing motion in micron scale tufted cells waving in a fluid filled inner ear, needing to go through complicated processing to bringing out powerful cognitive, emotional or even physical responses from a listener.  But what we think of as a soft interface between air and fluid will actually reflect away most sounds without something to bridge the divide.  Something that, based on its stiffness and structure, can act as a natural or induced amplifier and overcome the normal difference in impedance that lets us hear air borne sounds in our fluid filled ears.  And while James Wheldon Johnson’s old song is wrong and the ear bones (ossicles) are not connected to the headbone (skull), bones are critical to normal hearing.
Hearing airborne sounds requires a tremendous amount of amplification, and much of it depends on lever action by the ossicles, the three tiny bones that link the air outside the eardrum to the fluid in the cochlea via the oval window.   The malleus (Latin for “hammer”) attaches to the eardrum which has an approximate surface area of 55-60 square millimeters.  The innermost surface of the malleus articulates with the much smaller incus (anvil) which then passes the pressure onto the stapes (stirrup) whose faceplate contacts the oval window with a surface area of only 3 – 3.5 square millimeters.  This allows the three bones to provide 22 times more pressure to the inner ear than received at the eardrum, while still responding fast enough to maintain the exquisite timing needed for proper pitch discrimination. But despite their rigidity compared to the other elements of the peripheral auditory system, these bones are delicate and subject to all the other woes that precise skeletal joints are heir to, ranging from dislocation to arthritis.  While many clinical treatments have emerged to treat damage to the ossicles, they still remain critical and highly vulnerable elements in the hearing pathway and pathology or injury can have serious and sometimes permanent effects on detection of airborne sounds.
But we hear with more than just our ears, as you can tell if you go to a concert for the deaf or watch Evelyn Glennie perform.  Due to her severe hearing loss, she often performs with her feet bare to pick up vibrations from the stage and her body placed precisely to pick up vibrations directly from the instruments.  Like her, your entire body is sensitive to vibrations and your skeleton can act as a series of rigid low frequency transducers. In humans, this pathway is limited to detecting (not hearing) very loud low frequency vibrations (or, more often, a pathway to induce vibroacoustic disease as often experienced by heavy machinery operators).  However, it is a remnant of the earliest way vertebrate animals detected sounds when they emerged onto the land hundreds of millions of years ago.  Many non-avian and non-mammalian land animals still rely on transmission of lower frequency sound through skeletal pathways, called the “extratympanic pathway” that transmit vibrations through their limbs to their shoulder girdle and finally to their skull and ears.  But this evolutionary “remnant” has provided us with an opportunity for overcoming some forms of damage to our tympanic pathway.  By vibrating our skull, some hearing aids such as the Baha® bone anchored system or Advanced Brain Technologies’ wearable Bone Conduction System called WAVES™ use this lower frequency pathway transmit vibrations to the inner ear directly to overcome some of the drastic effects of damage to the tympanic system.   So while it seems counter intuitive, our densest bodily structures are critically important for maintaining one of our most fluidic and delicate sensory systems, and highlight how no one system is ever truly isolated from the rest of our physiological makeup.

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Use It or Lose It

Use it or lose it, we are all familiar with this adage. It is true for the body and true for the brain.

Without sufficient sensory stimulation a child’s brain does not develop as it should. Nor does an adult brain maintain full  functionality as a  result of negative plasticity. The auditory system thrives with the right input and suffers if deprived of sound or overstimulated by noise.

A new study by researchers from the Perelman School of Medicine at the University of Pennsylvania shows that declines in hearing ability may accelerate gray mater atrophy in auditory areas of the brain and increase the listening effort necessary for older adults to successfully comprehend speech.

Hearing aids can be an effective intervention. Another approach to  consider is music listening therapy. This is  neuroauditory training to improve sound brain fitness in part by stimulating the frequency bands where the deficits exist with specially modified music.  There has been good success helping people with mild hearing loss through the use of The Listening Program®. In many cases listeners no longer require hearing aids, because they trained their brain to better understand what it hears (auditory processing).

Many audiologists will share that when patients with mild hearing loss wear hearing aids for a period of time that their auditory discrimination improves on tests without the hearing aids. This is due to the brain now being able to perceive the auditory signal through sound amplification. The increased signal is enough to improve brain processing. In my opinion, a course of The Listening Program should be considered prior to using hearing aids in cases of mild hearing loss, and definitely needs to be used along with hearing aids. This is something proactive that can be done to stimulate the brain so people can continue to enjoy the richness that exists within the sounds of our loved ones voices, music, and nature.

Read more about this study published in the Journal of Neuroscience here.

Music Shown to Improve Communication in Toddlers with Cochlear Implants

A new study reveals that music activities can improve communication in toddlers who have received cochlear implants.

Some infants who are born with impaired hearing and who cannot benefit from hearing aids are likely to gain 90% normal hearing ability by undergoing a cochlear implantation procedure. Following the operation, however, the child — who never heard before — undergoes a long rehabilitation process before he or she can begin to speak.

In the present study, Dr. Dikla Kerem of the University of Haifa examined the particular effects that music therapy has on the potential development of toddlers (aged 2-3 years) who have undergone cochlear implantation, specifically in terms of improving spontaneous communication.

“Music comprises various elements that are also components of language and therefore as a non-verbal form of communication is suitable for communication with these children, when they are still unable to use language. Communicative interactions, especially those initiated by the toddlers, are critical in the development of normal communication, as they are prerequisites for developing and acquiring language,” explains Dr. Kerem. She adds that the toddlers undergoing rehabilitation are under much pressure from their surroundings — especially the parents — to begin talking, and sometimes this pressure makes them become introverted. As such, music therapy lends itself to strengthening these children’s nonverbal communication and thereby lessens the pressure on them for verbal exchange and response.[1]

Music can serve to open up the auditory receptivity of these children, lowering their defenses and providing an opportunity to gradually process and understand the components of sound that make up receptive and expressive language.  It is a way into a fragile system in need of gentle stimulation and support.

Read the full article.


[1] University of Haifa (2010, January 7). Music therapy can assist toddlers’ communication rehabilitation process. ScienceDaily. Retrieved January 7, 2010, from http://www.sciencedaily.com­ /releases/2010/01/100106093636.htm