Fun With Data: Listening to the Brain
In this video we’re listening to raw brainwave data that has been translated into sound and time-stretched to match the original length of the video clip (shot with a cell-phone). We’ve uploaded the original data file from from the EPOC in three formats – Excel, .txt, and CSV – along with the matlab algorithm we used to write the data as an audio file. If you’re interested in messing with the audio track, here’s the original audification, and here’s the time-stretched audio from the video clip. This audio was generated from a single column of data, and this is just one example of how data from the EPOC can be translated into sound… if you haven’t had a chance to get your hands on the device, feel free to download these files and play around!
Analysis of the Audio:
You’ll hear a hum enter at around 6 seconds, and leave around 17 seconds, which corresponds to a 10 second period when Steve closed his eyes. Going one step further… we can use a tone generator to approximate the frequency of this hum to 469hz with a +/- 10hz accuracy (when the file is played back at 1/8 the original speed). We can then calculate that 469hz at 1/8th the original playback speed (44,100 samples per second) corresponds to a periodicity of ~11.85 samples in the original data. This translates to a ~10.79hz periodicity in the original data file, as the data sampling rate of the EPOC is 128 samples/second…
“Hans Berger made many discoveries from the EEG recording and he found that the brain oscillate at about 10 cycles per second when the eyes are closed and relaxed and he called them alpha waves.”
Source: The Brain & the Mind. Psychology Volume 2. 2002: 97.
…and that’s how we can utilized auditory data analysis to confirm the existence of Alpha Waves!