Lecture delivered to the
World Organization Meeting of the
Institutes for the Achievement of
Human Potential. May 1994, by
William P. Mueller Vice Chairman of the
Board of Directors
Transient
Electronic Auditory Stimulation
The Institutes have
known for forty years that certain brain-injuries cause hyperactive
auditory sensitivity. In the past twenty years others have also begun to
study this problem. I first beame aware of that condition when I met
David, an eight year old brain-injured child at The Institutes who had
this problem. He screamed at the slightest noise. In fact, he screamed
eight hours a day. His parents whispered all day to keep from setting him
off. When they arrived at The Institutes he was given the auditory
stimulation program as part of his overall program. His parents were
instructed to bang pots and pans randomly around the house! David's mother
told me she laughed all the way home after that initial visit. However,
they did The Institute's auditory stimulation program and within two weeks
David was no longer hypersensitive to sound.
Posterior cortical mid
brain-injured children ( those children commonly labeled autistic) are
known to have dramatic auditory hypersensivity. Some report being able to
hear water running in the pipes underground and the beating of peoples'
hearts. Others display obvious pain at the slightest sound and cover their
ears if someone touches their hair.
Rub inside your ear canals with
your fingers and you might get a small sampling of the kind of sound that
would be experienced when someone gently puts their hand on the head of
such a brain-injured child. If you do it while someone is trying to speak
to you you will find you are functionally deaf and unable to follow what
is being said..
About a year ago the Institutes received a machine
called an AudioKinetron. The AudioKinetron was designed by Guy Berrard to
treat brain-injured children using music as a kind of
stimulus.
Parents have been reporting positive changes occurring in
their children after treatment with the AudioKinetron. Some parents have
observed a marked
decrease in
their child's sensitive to sounds, decreased screaming , decreased
hyperactivity, less tendency to have temper tantrums, deeper, better
quality sleeping, increased attention, interest in their surroundings and
improved language . Some of the children have shown affection for their
family and friends first time in their lives.
The
creators of the device believed that the machine exercised and trained the
muscles in the ear. "Earobics" they called it. Further they described
sound as "nerve food" or a source of energy for the body. They also
ascribed a kind of intelligence to the ear muscles.
The changes
in the children were undeniable and they were important changes. The
children themselves reported that the auditory stimulation helped them by
making their lives easier and more enjoyable. However, as we studied the
device and the results of treatment we began to formulated a completely
different view on how and why the machine worked.
Since
brain-injury is in the brain not the ear we knew that these children's
problems were not in their ears any more than a mid brain-injured child's
problem is in his legs.
The study of psycho-acoustics is helpful in
defining the links between a healthy auditory pathway and the
brain-injured child's auditory pathway. Unlike the eyes which can be shut
when looking into the sun, the brain has limited mechanical ability to
control over-modulation. However, the brain does have the capability to
affect and manipulate incoming auditory stimulation.
The brain has
the ability to rest from auditory stimulation simply by ignoring it.
Children are especially capable of "zoning out" when something they don't
want to hear is being said. The brain also has the ability to "normalize"
auditory stimulation. When we first turn on a transistor radio the sound
is awful. No low frequencies, no high frequencies, very low fidelity. But
we quickly become "accustomed" to it and it no longer sounds "bad" or
"wrong".
Another psycho-acoustic ability is called the "Cocktail
Party effect". Someone can be talking to a person in a large crowd when
suddenly another voice catches his attention. If the new voice or subject
is interesting enough, a person can tune out the person in front of him
who is producing the loudest acoustic wave form and focus on the much
softer auditory stimulation from across the room. This function is a
filter, but one of astonishing complexity. In order for a system (the
brain) to be able to filter out higher volume stimulus of a similar
frequency to lower volume stimulus, the system must be able to predict the
behavior of both sets of stimulus simultaneously. Speech pattern
recognition is fundamental to this activity.
New analog to digital
encoding schemes used in digital audio systems are designed around the
brain's ability to "fill in the missing information" thereby allowing the
converter to throw away audio data and compress the bit stream. The
smaller bit stream allows more information to be stored in less disk
space.
The brain has the ability to normalize and remember acoustic
environments. When a person first enters a very loud room he is accosted
by the sound, his adrenaline levels rise and his ears hurt. But after a
few minutes his hearing changes to accommodate or "normalize" the
environment. This is not so much his tensor muscle tightening but his
brain making sense of the noise in the room. In fact the next time that
person enters the room it will not be so uncomfortable. Speech recognition
will be easier and the sense of "loudness induced confusion" will be less.
My wife and I have three young boys and they can make a real racket when
they want to. Our last house had a large ambient kitchen. The boys were so
loud in it I wondered whether I could even live in the house. Within a
couple of weeks the room didn't bother me at all. The blind singer Stevie
Wonder is reported to have a legendary ability to snap his fingers when
first entering a room and from the echoes learn and remember it's
boundaries.
The brain has the ability to differentiate between
direct and reflected sound. The difference between the perceived sound in
a room and the sound recorded by a omni directional microphone is
dramatic. The microphone always sounds more reverberant and hollow. I
could never record a symphony from the balcony, the orchestra would sound
too far away. But it can be a very satisfying musical experience from
there, especially if you can see the orchestra.
So far we have seen
psycho-acoustic effects in well systems range from manipulation to mild
defense. But now lets look at the severely distorted system in the
brain-injured child. Because of his brain-injured auditory pathway.
Certain sounds scream at him like a runaway locomotive's brakes,
overwhelming him.
We have seen that the brain can manipulate
auditory stimulation and does so routinely. When a hurt child experiences
uncomfortably high sound pressure levels his brain goes through a series
of self protective steps. The first step is like the "cocktail party"
effect, selective listening. The second is compression, the ability to
reduce or try to control the effect of loud auditory stimulation. The
third level of self defense may be called suppression.
Stimulus
induced deafness.
Some brain-injured children live in a world of
chaos caused by the bombardment of auditory stimulation. Their brains are
in a state of sensory defensiveness, suppressing or distorting all
input.
Why does the AudioKinetron work?
System response time
delay.
All systems whether mechanical or biological have a finite
duration of time between the command to action and the response. In
electronic devices this time is the speed of light. In mechanical systems,
response time is a function of efficiency of motion. In biological
systems, response time is widely variable and dependent on a host of
factors. Restedness, nutrition, alertness and most importantly wellness.
Glenn has described the time delay experienced by stroke victims which
makes it almost impossible for them to do something as fundamental as
answer a simple question. Even when they know the answer! Because of
system response time delay, by the time the victim has mustered a response
to the question, the person asking the question has left or moved on to
another question. As a graduate of the How to Multiply Your Baby's
Intelligence Course, I have been taught to be patient and wait for my baby
to respond to my attention, allowing his newly developing brain time to
affect a response.
Brain-Injured children do not have a well
system. Therefore their system response time is delayed. When one combines
auditory hypersensitivity with a delayed response time a picture emerges.
Only a signal sufficiently long enough to exceed the response time of the
system will elicit a defense mechanism.
The AudioKinetron is a two
stage device. The first stage is a simple cuts only graphic equalizer that
is designed to lower certain sound frequencies by forty decibels. This
allows contouring the stimulus music to the particular patient's
hearing.
The second stage functions by taking music and creating
from it a series of powerful, short duration, random, high frequency
pulses. As the child listens to the music, he is attacked by the
accompanying pulses. His hypersensitivity causes his brain to react but by
the time his brain overcomes the time delay, the pulse is gone. The brain
no longer has anything to defend against so it relaxes. Eventually the
brain learns it is futile to either try to predict or respond to the short
duration stimulus. Hyperactivity starts to diminish, the child begins to
emerge from below.
This therapy, which I call Transient Electronic
Auditory Stimulation or TEAS is electronic pots and pans. The music is
there to entice and relax the child, the stimulus is unpredictable and
short duration, consequently the brain can't defend against it.
How
can we become more successful using this information to treat
brain-injured children who have these kinds of auditory
problems?
Our first goal is to improve therapy procedures using
existing or available equipment.
What are the biggest problems
facing us in this goal?
First and foremost,
analysis.
Brain-injured children have severe problems communicating
with the outside world. The standard audiology exam requires skill in
listening, concentration, sophisticated communication and is only designed
to be effective within a normal to low hearing range because it is
designed to reveal hyposensitivity or loss, not
hypersensitivity.
We need a
way to perform an active, non-invasive, safe, highly accurate, high
resolution frequency analysis of the auditory pathways of all
brain-injured children.
We began investigating the Evoked Potential
method of audiology about a year ago. Evoked Potentials are electrical
signals evoked within the brain by exterior stimulus. This technology
seemed promising at first but a number of things made it inappropriate for
our work. We could not find a system that was more than a simple Pass/Fail
test. This gave us none of the specific frequency sensitivity that we
needed to use the AudioKinetron properly. Second, we were told that
uncooperative patients needed to be sedated for the test. That was the end
of that.
A number years ago it was reported that high frequency
whistling could be heard coming from the ears of cats. As a result it was
thought that our auditory system was not, as we believed, a passive system
receiving stimulus in the form of sound waves, but was instead an active
system somewhat like an AM or FM radio station. Sound waves, generated by
nerve endings in the middle ear, are transmitted to the outer ear where
they are modulated by external sound sources and are then re absorbed by
the ear drum. The carrier wave is stripped away from that signal
neurologically and the resultant signal is what we perceive as
sound.
These whistles are now called Otoacoustic
Emissions.
Whether the original theory is correct or not is
somewhat irrelevant to our needs. Otoacoustic Emissions seemed to promise
a new insight to the function of the Neuro-auditory system. However when
we first discussed this with the manufacturer they told us that
autoacoustic emissions were only a resonance of the nerves in the inner
ear. But I was sure that otoacoustic emissions were a result of active
control from the hearing center in the brain. Consultation with Glenn
confirmed that there are more nerve pathways from the brain to the ear
than from the ear to the brain. Once again we found ourselves on the other
side of the fence from a manufacturers theory of operation of his own
machine.
Supporting our view is a just released study by the Mayo
clinic which confirms the efferent action on autoacoustic emissions
through the neural pathway from the brain. We were relieved to learn of
this report. Without this confirmation, Otoacoustic Emissions Analysis
could have been another expensive dead end. Now we may have a powerful
tool to accurately analyze the hearing of a brain-injured
child.
Two months ago Gabriel Medick volunteered to be tested by
the Virtual 330 otoacoustic emissions system. Gabe is extremely hyper
sensitive to many sounds and is receiving Transient Electronic Auditory
Stimulation at the Institutes. On his first test on the machine Gabe
exhibited a narrow band hypersensitive spike of forty to fifty decibels at
4KHZ. When the spike literally jumped off the computer monitor's display I
turned to Glenn and said "There it is! That's what we've been looking
for!". The audiologist who was demonstrating the machine, turned to me
wide eyed and said "I have never seen anything like that in my life!".
This was the first time he had tested a brain injured child with the
machine. We continued to test Gabe but it was soon obvious that he was in
abject pain every time the machine's test frequency approached 4KHZ. He
would start to create noises and writhe but continued with the test
because he knew he was helping us with something important. We took a
break and Gabe typed a message to his mother that he had to block the
sound because it was painful! So we stopped the test.
Later we set
up the machine again in order to do a demonstration for the staff and the
board of directors. While one member was being tested, I noticed the
computer was running much more quickly and with higher resolution. I asked
the audiologist what was going on and he told me he was now using a much
shorter duration test pulse and taking far fewer samples per frequency.
That day even our failures had supported the theory. The test signal that
we used for Gabe was of a much longer duration than that for the board
member. Just long enough to elicit a defense response from Gabe's brain,
except for the first time when it was a surprise. Because the tones used
by the machine are sine waves progressing evenly from low to high
frequency he was able to predict the tones after the first test. He even
told us so.
The optimum instrument parameters for testing
brain-injured children should be:
1. Shortest duration pulse.
2.
Smallest number of samples needed to get a result.
3. Lowest amplitude
signal, so as not to present a painful stimulus to the patient.
We
learned something else that day. Even a test that is benign to most
children, even preemies, can be disturbing to brain-injured children
unless the test parameters are contoured specifically for them. Since that
time there has been a published study citing the discovery of a 4KHZ
hyperactive anomaly in some brain-injured children using otoacoustic
emissions analysis techniques.
During a board meeting after this
test the entire clinical staff discussed this issue and decided that if
the children were to wear ear plugs that the level of unwanted auditory
stimulation would drop and their condition should improve. This alone
would not be an acceptable therapy, only a crutch that would not be self
eliminating. However, if we had the kids wear the ear plugs before TEAS,
their chemical wall of defense should be at low levels and therefore TEAS
should be more effective. The staff started with the ear plugs and the
response from the children and their families was immediately positive. By
improving the effectiveness of TEAS the plugs are self
eliminating.
The next step is to improve the TEAS machine itself.
Right now the machines are like shot guns shooting at a bullseye on the
wall because the stimulation signal is fairly broad band. Without
extremely accurate audiology exams this is the only way to be effective.
In fact the staff have so little faith in the conventional audiology exams
that they are not even using the multi-band filter stage of the machine.
However with more accurate otoacoustic emissions analysis we can first
start to use the machines more effectively and second begin the design of
a second generation of machines that focus directly on the hypersensitive
frequencies of the child making the therapy more comfortable and
effective.
We envision a machine that can, at the push of a button,
perform a complete audiology exam, adjust the necessary filters
automatically and then administer appropriate TEAS directly to the child.
In addition, we intend to design a better TEAS system using pulsed noise
as the stimulation signal and music composed specifically for the children
in this project. We are also designing a digital recording/storage system
that will allow TEAS to be administered to children at home by parents as
well as on campus. This could increase the frequency of treatment as well
as make it more cost effective to the parents.
Even though we are
only at the beginning of Transient Electronic Auditory Stimulation, the
Institutes for the Achievement of Human Potential have been successfully
administering mechanical Auditory Stimulation for many decades. I hope our
forays into the technological side of this subject can lead to more
understanding of the problem and so further the successful treatment of
brain-injured children.
Note: Since this lecture was given a major study (Rimland
and Edelson) concluded that there was not a significant difference in the
results whether a filtered or unfiltered signal was used in regard to
Autistic children. The significance of this finding for us was:
1. The
importance of the audiogram was lessened. If the mother said her son was
hypersensitive to sound then we could assume he was, instead of trying to
get an audiogram from an individual who could not give us an accurate one
in the first place due to his condition.
2. If the filters did not have
to be used, then encoded music could be transferred to an appropriate
medium and distributed directly to parents, thus bypassing the high cost
of travel, hotels, etc.
3. This was good news for parents.
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