Technical
Information
Information
about The EASe CD Series 1
A
wide array of individuals have demonstrated hypersensitivity to normal sensory
input. This sensory hypersensitivity can be tactile, visual, auditory or other.
Brain-injured children often exhibit sensory control problems. Auditory and Visual
hypersensitivity has been demonstrated by children with symptoms described as
Autistic. Often these and other brain-injured children exhibit a startle reflex
that does not abate with continuation of normal stimulus. One successful method
of desensitizing these children has been auditory stimulation in the form of transient
sounds, (wood blocks, horn bursts, etc) to randomly stimulate the auditory pathway
of the brain . The transient nature of the stimulation does not over stimulate
the child like a continuing noise might. The frequency of the stimulation eventually
builds enough information in the auditory centers of the brain to help it reach
the next stage of development in which it can control auditory startle reflexes.
Another method of response to this auditory problem has been the use of electronic
auditory stimulation. This method utilizes a machine which modifies music with
random bursts of high frequency energy to deliver auditory stimulation to the
patient. Children afflicted with auditory hypersensitivity have demonstrated positive
effects. These effects include lessoning of their auditory hypersensitivity, increased
communication and an increase of affection.
However, this therapy is expensive
in both money and time. It is not available everywhere so parents must travel
long distances and incure travel expenses in addition to the treatment fee itself.
Studies have concluded that in regard to these particular individuals, the basic
signal of the machine is as effective as the signal when input filter shaping
is used (Edelson, et al, 1994). This information suggested that the signal from
the machine could be recorded onto a suitable medium and distributed to many more
individuals than who were presently able to afford the use of the machine.
In
an effort to make this type of electronic auditory stimulation more affordable
to parents of brain-injured children, Vision Audio Inc. has transferred licensed
music through an auditory stimulation device to Compact Disc with encouraging
results.
To test the electronic viability of such a procedure, Vision
Audio Inc. recently analyzed the performance of the machine. The procedure was
thus.
1.
A white noise source was equalized for constant amplitude and applied to the input
of the machine. The signal level was adjusted for unity gain in and out of the
machine.
2. The machine's sensitivity was adjusted so that proper level and
efficiency action (encoding) was achieved with the given source signal.3. The
resultant signal was digitally encoded and recorded using a digital hard disc
recorder.
4. Fast Fourier Transform analysis (FFT) of the signal, both directly
from the machine (figure 1) and from the digital hard disc recorder (figure 2)
was done and time slices of that analysis were saved as PICT files.
5. Analysis
of the direct output of the system and the digital recording revealed very little
differences in frequency response or dynamic range.
figure
one
 |
figure
two
 |
CONCLUSION
The
dynamic range of the the auditory stimulation device exceeded seventy decibles,
the high end performance of analog recording devices. The real story though was
in the high frequency requirements ot the auditory stimulation device. During
the BURST mode the device output a signal exceeding eighty decible dynamic range
at twenty thousand hertz. The only medium capable of handling that kind of extreme
frequency content with acceptable linearity and distortion is digital.
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