acustic_brainstem_response_demo_idea.txt

If we reach the point where we want a fun distraction, I ran into
something in pediatrics that might be a neat demo of a different kind of
analysis of biopotentials we can do with the rev1 board: recording the
click-evoked acoustic brainstem response.

https://en.wikipedia.org/wiki/Auditory_brainstem_response

Basically this is looking for stereotyped EEG activity in the brain in
response to a sound.  It's widely used as a standard screen for hearing
problems in infants.  The trick is that this response is relatively
small compared to the electrical noise and all of the other activity
going on in the brain, so you have to average it over 1000+ times of
playing the sound (usually a short click played ~20 times a second, so
you could collect 1000 recordings in less than 1 minute).

The same approach is used for things like detecting the P300 potential
that can be seen when the brain "notices" something new, but this would
be a longer experiment (since most of us can't notice something new 20
times a second ).

Here's my rough guess of what would be involved:

1) build a splitter cable to go from a male headphone jack to two
touch-proof connectors and a female headphone jack.

2) make a wave file with the clicks and upload it to music player that
runs off a battery (e.g. a phone, so we don't bypass our isolation).

3) hook up the phone to the splitter cable and the splitter cable to a
pair of headphones and one of the channels on our device.

4) hook up the the remaining EEG channels (RLD in lower forehead,
positive in upper forehead, two electrodes on the mastoids as negative
electrodes)

5) play the sound and record the EEG and the synchronized sound track
from the patch cable.

6) Use the clicks on the soundtrack to chop up the EEG into ~40 ms
chunks and average them together to get the audiotory brainstem
response.