The frequency Hertz range defines which brainwave you’re talking about. For example, Alpha for example is any brain activity occurring between 7.5Hz and 13Hz. Since there is activity in all areas at all times, we quantify each of these brainwaves by measuring the amount of power within the range and we call this the Power Spectral Density (PSD for short). Think of this like the signal strength of an old FM radio station. This is measured in dB.
The gauges at the bottom are the average values for the session. Many believe that what you should be looking for regarding meditation is increased Alpha, these gauges help with that, so that you can see how your average Alpha has varied from session to session.
The chart on the left shows left brain vs right brain activity. Some believe that balancing left and right (coherence) brainwaves is important, so this chart helps with that.
For non-professionals, the RAW data view is mostly helpful for showing interference to let you know how clean your data is. The better the signal the less variance you will see here. Blink and Jaw Clenching will show big spikes. If the headband isn’t making good contact on one sensor, you will see the data jump up and down much higher than on a clean signal. For the absolute best result keep your eyes shut and remain still, then compare this to how it looks when you blink and move your head while talking.
Accelerometer and Gyro are movement sensors, again useful to know if someone is moving their head. If you see very high Delta and lots of movement, then the Delta is probably interference.
Battery I think is self explanatory If you’re trying to do a sleep study this will let you know exactly how long your Muse can last before it dies. It’s worth noting that if you’re in the middle of a recording with Muse Monitor and the battery on the Muse dies, Muse Monitor will pause the recording and give you as much time as you need to reconnect the Muse before continuing automatically. If you are running a study, you can use two Muses and just swap them out during a recording and Muse Monitor will reconnect to the second to continue recording.
Interaxon have a really good beginners guide to brain waves here.
Lastly, for an interesting read on identifying relaxation, check out the research paper “My Virtual Dream: Collective Neurofeedback in an Immersive Art Environment” by Natasha Kovacevic, Petra Ritter, William Tays, Sylvain Moreno, Anthony Randal McIntosh.