**
**
**Recording**

The following charts were obtained from an off-line analysis of a recording session in
which the subject was asked to produce and suppress the Mu rhythm in 30 Sec time
intervals. The first 30 Sec time interval of each file, the subject was asked to
produce the Mu rhythm. The Electroencephalogram signals were amplified and digitized
at a sampling frequency of 500 samples/sec. The off-line analysis was performed
using the MATLAB software.

**Off-line analysis**

Frequency analysis on the Electroencephalogram signals was performed using two
Goertzel algorithms. The two frequencies investigated using the Goertzel algorithms
were 6 Hz and 12 Hz. The Goertzel algorithm provides a meaning result after N
samples of the signal being studied have been processed. In our experiments we chose N =
500 such that within a given 30 Sec time interval, a total of 24 windows can be
taken. Therefore, within a 30 Sec interval in which the subject was asked to produce
the Mu rhythm, there should be 24 Mu rhythm detections. A Mu rhythm detection was
determined when the following was true: (Power in 12 Hz band)/( Power in 6 Hz band) >
1.

**Interpreting the charts**

The blue bars corresponds to Mu rhythm detections made by the algorithm which
implemented the two Goertzel algorithms. The purple bars corresponds to Mu rhythm
collapse detections made by the algorithm. Therefore, in the 30 Sec time intervals
in which the subject was asked to produce the Mu rhythm, there should be a total of 24 Mu
rhythm detections (i.e., blue bar -> 24 and purple bar -> 0). Similarly, in
the 30 Sec time intervals in which the subject was asked to suppress the Mu rhythm, there
should 24 Mu rhythm collapse detections (i.e., purple bar -> 24 and blue bar -> 0).

In the charts below, the first window corresponds to the subject being asked to produce
the Mu rhythm, the second window to the subject asked to suppress the Mu rhythm, the third
to the subject being asked to produce the Mu rhythm, and so forth in an alternating
fashion (i.e., Mu, No Mu, Mu, No Mu, etc.).