Relation between brain waves, summary chart, three sounds


#1

Here is a summary of my understanding, please correct me where I’m wrong. There are some questions at the end.

  1. The Muse headband measures five types of brain waves: alpha, beta, gamma, delta, theta.

  2. These are combined into a composite score on a scale from “calm” (goal for meditation) to “active”. This score over time is displayed in a graph, divided into three zones: calm, neutral and active.

  3. The exact algorithm for combining these is a “secret sauce”, but presumably higher alpha waves are a big part of the goal state of relaxed focus.

  4. The storm sounds get softer as the graph dips lower. There’s no delay in this feedback.

  5. The birds start chirping after you’ve been in the calm zone for five seconds.

  6. The waves lapping are a constant, which do not vary in presence or volume, and to help avoid startling you when the storm sounds cut out. (I’ve turned them off entirely to focus on the two sounds that actually provide feedback.)

So here then are my questions:

  1. Is there any inaccuracy in my summary above?

  2. At what level do the storm sounds cut out entirely? At 1/3? I don’t think so because I’ve heard storm and birds at the same time. At 1/6 – the lower half of the calm zone? At 1/10?

  3. I’ve read about bird wing flapping sounds for when you scare the birds away with a storm. I don’t think I’ve heardIs that for an earlier app? I’m using whatever is current as of December 2017.


#2

My best guess is as follows:

  • There are two sets of feedback, one for the running average of the two front electrodes, one for the running average of the two rear electrodes
  • On ambient (my favorite) the frontal average has a slightly higher tone whose volume corresponds to the alpha level. The rear average has a slightly lower tone which corresponds to rear alpha.
  • When rear alpha stays over a threshold for however many seconds, it starts playing “pulses”. When frontal alpha stays over threshold, it start playing chirps.

#3

There’s a 500-millisecond delay between what the headband is detecting and the app’s response. A discussion thread is here.

On Android, the flapping wings sounds were removed from the app when version 2 was released in early 2016. I think they were removed from the iOS app in 2015.


#4

Thanks. So there’s no purposeful delay in the storm feedback, but a necessary processing delay of half a second. For the birds, there is an intentional delay of 5 seconds before I get my chiping reward.

So it seems like my main remaining question is: Why do I often hear birds and storm at the same time?

Subquestions: Does the bird range exactly equal the lower 1/3 of the chart marked “calm”? Or is it the cut-off even lower, say the bottom 1/6 of the chart? Where does the storm go completely silent? At 1/3? I don’t think so. At 1/6, at 1/10?


#5

@Worn-out_Amygdala … did you used to be @linky7? Or is there a bug in the discobot forum software? I have a notification that I liked linky’s post, when in fact I liked amygdala’s. See screenshot:


#6

After three years of using Muse, I’m 99% certain that’s correct. Interaxon employees rarely respond to posts in the Using Muse forum, but you can probably get confirmation by sending a private message to Interaxon’s customer support. FWIW, I don’t think customer support has ever failed to respond to any of my inquiries.

I don’t know, but I have a suggestion: try using the “City Park” soundscape instead of whatever soundscape you’re currently using.

Version 5 of the Android app (released seven months ago) introduced a bug where the birds would unexpectedly stop playing while a user is in the “calm” state. This bug hasn’t been fixed in the current version of the app (v. 6),

The bug is a problem because it makes it difficult to detect when you’ve drifted from “calm” to “neutral”. Fortunately, the City Park soundscape contains an audio cue that’s not available in the other soundscapes: when you’re in a neutral state, this soundscape plays human voices – they’re indistinct (the language sounds like it might be Asian), but they’re clearly audible. And when you’re in a calm state, the human voices go away. This makes it easy to tell which state you’re in.

That’s a notification that @linky7 liked one of your posts. :blush:


#7

The exact algorithm for combining these is a “secret sauce”, but presumably higher alpha waves are a big part of the goal state of relaxed focus.

The storm sounds get softer as the graph dips lower

If higher alpha waves means relaxed focus, then should the strom sounds get harder as the graph dips lower. I am trying to understand on a high level what does high frequency of alpha waves mean?


#8

@Ven – I’m no expert in alpha waves, and apparently there are more than one kind, indicative of more than one mental state.

I didn’t mean to imply that higher alpha waves corresponded to higher positions on the Muse graph. In fact, I was guessing the opposite, that higher alpha waves (in combination with other patterns in the other kinds of brain waves, and in combination with other factors like timing, all mixed according to some secret Interaxon sauce) presumably corresponded to lower positions on the graph. The graph is indicating a range from calm (low on the graph) to active (high on the graph). And apparently calm ≈ focused and active ≈ distracted.

So lower on the graph means calmer, and one way that Muse might be concluding calm is by measuring higher alpha waves. But I don’t know and Interaxon won’t say.


#9

So, with the understanding that there are three kinds of sounds (monkey mind active feedback = “storm”, static background = “waves”, and reward continued calm = “birds”), and with the understanding that birds kick after 5 seconds in the calm zone (below the 1/3 mark in the graph), my remaining question is this: Does the variable-volume feedback ever drop to zero volume? Or, as I’m beginning to suspect, is the only way for it to be completely absent is to have a chart that shows a flat line along the very bottom: that if you are 1/10th up the chart, the volume of the feedback will be 1 on the volume dial, and hover just within the calm zone, you will hear both birds and also feedback at just below 1/3 of full volume?

Note that if you have the background sounds on, it will be harder to notice one way or the other. The background sounds for the cityscape seem to include children’s voices, for example. I’ve been setting the static background volume to zero, and I’ve never heard complete silence, even as I sometimes dip very low in the summary graph.


#10

The variable volume feedback would be zero, or at least at it’s minimum value, when both the front and rear metric values are below the threshold for “calm”


#11

Right, I should have mentioned in my previous comment that, like you, I set the “Background” audio level to zero:

I agree that the Background audio makes it more difficult to detect changes to the “Feedback” audio level.

Not in my experience. Even in parts of sessions that have shown a flat line along the bottom of the session graph, the Feedback audio was still slightly audible.

There’s one exception to this: in the current Android version of the app (v. 6), there’s a bug that will sometimes cause the Feedback audio to stop playing. This, combined with the other audio bug that sometimes causes the birds to stop playing, has resulted in a few sessions where there was several minutes of dead silence. I’ve found no correlation between this Feedback silence and the level of calm – it appears to be a random bug.


#12

I’ve been Musing for only a couple weeks. Early on, I selected the Rainforest soundscape and turned off the background. I have feedback, the storm/weather noise, set at about 1/3 volume. I have the birds set at full volume. So far this works well for me.

I did not like the background sound. To me, it was just added confusing noise which made it more difficult to hear the weather, and did not help my meditation.

I have the most recent version of Muse (bought in Feb. 2018). For me, the feedback disappears when I enter the calm level. Maybe this is because I have it set to 1/3 volume? But to me, it doesn’t make sense to have the feedback still audible when we have reached the calm level. That’s when the birds are useful as a cue. The weather feedback is redundant. The less noise the better, especially when the noise does not convey any useful information.