Binaural beats | Hacker News Reader

Binaural beats

en.wikipedia.org

35 pointsmdturnerphys46 comments

See also the coolest auditory illusion I know of: https://en.wikipedia.org/wiki/Shepard_tone

I knew that sounded familiar!

"In The Dark Knight and the follow up The Dark Knight Rises a Shepard tone was used to create the sound of the 'Batpod' - a motorcycle that the filmmakers didn't want to change gear and tone abruptly but to constantly ascend."

I can clearly hear when the tone loops, so I don't really get what's the illusion. So it is as "impossible" to hear the beginning or the end of the given scale as it is "impossible" to see when the two pictures begin and start to fade in and out.

Many years ago I worked on a now defunct project (RapidLingual.com) that mixed binaural beats over spoken language lessons. Binaural beats had been marketed for a long time as a 'super learning' technique that could induce a state of mind that's more focussed and receptive of a lesson (though the theory was there, there was no study that confirmed it).

Unfortunately the guy who was supposed to write the lessons never really did his part and the whole thing collapsed, but it gave me a chance to play around with it and noticed:

- Binaural beats are common in urban environments for things like air conditioner units that resonate at slightly different frequency, but pair up for a loud binaural pulse

- Adding white-noise enhances the effect of the beats (you find similar backing noise in products like Holosync)

- You can only encode to FLAC. Because of the lossy psycho-acoustic nature of Mp3 encoding, it strips out the inaudible part of waves that you apparently need

- For a trippy experience, I wrote a program that fades the screen (red-black) in sync with the beats

> - You can only encode to FLAC. Because of the lossy psycho-acoustic nature of Mp3 encoding, it strips out the inaudible part of waves that you apparently need

This is not correct. You can lossily compress the audio that produces binarual beats and it's just fine. All it really is is two pitches being played, one of the left channel and one on the right. The two channels play tones that are almost the same pitch (but not quite, usually separated by 4-20 Hz). There's no inaudible part of the waves. Two sine waves work great, with no harmonics, and nothing inaudible about them. Unless your mp3 encoder is changing the pitch of the sine waves (which it isn't), it will work perfectly.

You can find all sorts of (compressed) Youtube videos with binaural beats that are reproduced correctly.

I said "apparently" as I never noticed a difference between flac and mp3.

What I read was along the lines of - one technique mp3 uses is to remove the parts of a sound file that the human ear doesn't actually hear - parts which would appear in flac and that apparently do have an effect of the beats.

Could have just been marketing hocus pocus, but who knows as all the encoded beats online appear as mp3s.

MP3 tends to remove some of the phase information (though I don't know how applicable this would be at lower frequencies) from the signal, which would quite likely have some effect on binaural beats.

It depends on whether you're using pure tones, or phase shifted audio. Binaural beats in phase shifted audio do not survive MP3 encoding, and require a high quality setting to survive Vorbis.

While we're on the subject of the brain handling things at a more raw level than you might expect, here's another interesting group of experiments: http://en.m.wikipedia.org/wiki/Mental_rotation. At university, we carried out some of Shepard and Merzlar's experiments to measure the rate at which our minds could rotate objects. Even though it subjectively feels like the mind has a graphics card that can rotate objects, it was still surprising to discover that the perception isn't an illusion—and to be able to measure our own mental rotation rates in degrees-per-second. It's not mentioned on the Wikipedia page, but I remember carrying out an experiment that showed that if it takes you, say, one second to mentally rotate an object by 60 degrees, then at the 0.5-second mark, you really do have a mental representation of an object that's rotated halfway (i.e., by 30 degrees). Maybe this isn't surprising to some people, but psychology is full of examples of the brain taking outrageous shortcuts, so it surprised me that mental rotation—which would appear to require a prohibitive amount of processing power—isn't being fudged by the brain.

Here's some software for generating them;

http://gnaural.sourceforge.net/

http://discord.sourceforge.net/

http://sbagen.sourceforge.net/

http://entrainer.sourceforge.net/

Or, since this is Hacker News, you can use ChucK, which is a realtime programming language for processing audio:

    SinOsc left => dac.left;
    SinOsc right => dac.right;
    300 => left.freq;
    310 => right.freq;
    while (1) 1::second => now;

The last time I looked at ChucK had to have been almost 5 years ago. I was doing some interesting phase shift work where I would offset one channel by a few samples. Lots of fun.

Are you talking about a fixed offset, as in https://en.wikipedia.org/wiki/Haas_effect, or a variable offset, sort of like a flanger?

or:

xmms tone://300;310

I used rhybag, from the author of sbagen, to create a melody for a song I've yet to finish writing. It's a very cool tool.

Some good, more general purpose and programmer-y alternatives:

ChucK => http://chuck.cs.princeton.edu/

Pure Data => http://puredata.info/

SuperCollider => http://supercollider.sourceforge.net/

There's also http://overtone.github.io/, which sits over super collider. Overtone provides an emacs mode, but you can also use it in http://www.lighttable.com/ which is a bit more accessible.

It's funny, here I was futzing around to make emacs part of my PD workflow... Thanks for the link, I hadn't heard of it before.

There is another open source software which generates binaural beats. The software is Paulstretch, an extreme-audio time stretching software I wrote few years ago: http://hypermammut.sourceforge.net/paulstretch/

Here is a screenshots of binaural-beats generator: http://hypermammut.sourceforge.net/paulstretch/screenshot3.p...

But I don't know if there are real psychological effects of the binaural beats :)

Paulstretch and ZynAddSubFX are both great software. Thanks for writing them!

Another entrant in the fascinating club of "weird but cool sounding things tried in our teens/20s in the hope they blow your mind but invariably don't" alongside lucid dreaming, smoking banana peels, and staring at the back of someone's head to see if they can sense your voodoo powers.

Lucid dreaming is actually pretty cool and did blow my mind. It's essentially not that different to temporarily being a god, with complete control over your environment. Takes a bit of getting used to, to not wake up as soon as you realise you're lucid dreaming ("oh my god, how exciting! Wait, no, don't wake up now!"), but once you get that down, your imagination is the limit. Pretty mind-blowing imho.

Make sure to try the demo at the top of the page. Our auditory system is really neat.

I have been running http://healingbeats.com/forum a large forum related to Binaural Beats for awhile, some good sbagen presets there.

Here is a good place to create and listen to binaural beats on your browser using the new html5 audio apis:

http://mindstate.michielroos.com/binaural-beats/

90 percent of them dont seem to have much effect, but i found a few that seemed to put me in a super deep sleep... like an audio mind massage. pretty sure it was a 3hz delta state, with out any weird static noises mixed in. i find those static sounds somewhat annoying, but did find a pleasant one with nature sounds mixed in there.

You get theese when the instruments in a section of an orchestra or band are out of tune. It's a very good "lazy" way of checking to see who's out of tune if you don't have perfect pitch.

As pointed out elsewhere in the comments, this is different.

This can be easily heard on a piano. Just play two adjacent low notes at the same time and volume.

No, it's different. That's a real beating effect. This is an phenomenon that happens when the two tones are heard separately in each ear and the beating just happens in your head. It tells us that our auditory system retains some waveform data, up to about 1000 Hz.

This is what I find fascinating about it.

I understand from a math/physics perspective why a microphone places betwen two sound sources playing slightly different frequencies "hears" the beat pattern. I don't understand why that still works once the two individual signals have made their way into your audio nerves and brain. (If I didn't have actual work I shoukd be doing now, I suspect I'd happily drop into a 6 or 8 hour wikipedia and google mediated deep-dive laymans research session.)

It's a phenomenon that happens to all waves, whether they are acoustic or electromagnetic. In fact, it's how your clock radio tunes to various stations. This property is a mathematical property of all waves, hence even when your brain mixes an electrical representation of the sound going into your left and right ears, you still get the effect.

For higher frequencies your auditory system doesn't retain the waveform information, so this doesn't happen.

I wonder if that's an evolutionary thing – somehow we evolved out the ability to retain phase difference information outside the frequencies where it's useful for stereo angular location?

The "~1000Hz" upper limit is pretty close to a 1/4 wavelength for a "phased array" of two ears ~100mm apart. That'd make it pretty ideal for angular discrimination based on phase difference.

You're pretty spot on here -- up to approximately 1500Hz, the auditory brain can make use of so-called inter-aural time differences which allow estimation of a given source's azimuth. After that, phase differences become ambiguous and the brain relies more heavily on inter-aural volume differences.

http://en.wikipedia.org/wiki/Interaural_time_difference

it's the pulsing that induces the altered states, you can use a metronome-like sound for similar results, this ones at 9hz which is mid alpha - absorbed in a good book frequency

a quick bit of supercollider code: play{SinOsc.ar(369.99,0,LFPar.kr(9))}

Knew about them for a long time. I am still not sure if these work for some people or not, because they don't work for me at all.

The following youtube video is a decent intro on binaural beats - make sure you listen with headphones. Also, everything after the 5:55 mark starts becoming an infomercial so you can stop there. http://www.youtube.com/watch?v=QCfUbFjin00

I don't think they work at all, especially because there are no studies proving binaural beats to be good for anything (except making money?). The only blind study Wikipedia cites was published in the "Journal of Alternative and Complementary Medicine", which isn't really a journal at all.

Edit: Found this study [1] looking at binaural beats and changes in EEG: "Analysis of changes in broad-band and narrow-band amplitudes, and frequency showed no effect of binaural beat frequency eliciting a frequency following effect in the EEG". This study is (conveniently) not cited in the Wikipedia-article.

[1] https://www.sciencedirect.com/science/article/pii/S016787601...

They are, however, good at sounding cool.

I'm convinced they "work" when done correctly. If the current brainwave frequency is too far from the desired state, the entrainment may not work, from what I've read. I hope they do more studies.

I first found out about binaural beats and brainwave entrainment in the 80's reading a book called MegaBrain by Michael Hutchison.

I went to his seminar. There was a device that generated binaural beats via audio and some flashing lights.

I closed my eyes, put on the headphone/helmet thingie. Did the program. My mind was 100% on the ball. Pshaaaw. Felt like nothing happened. Was skeptical. Gave up on it. Took off the helmet. Stood up. And fell back into the chair. Because the brainwave entrainment put me into a sleepy state.

While I understand that placebo's are powerful, I find it hard to believe that I imagined that deep a sleep, particularly when I had decided that it didn't work.

Flash forward years later, I figured they must have an app for the iPhone by now. So I searched and found several, but settled on an app called Brain Wave, by Banzai Labs. It isn't quite as strong an effect as with the light machine combined, but it does seem to get me into a deep sleep.

I understand this is anecdotal. Try downloading an app, do a program and judge for yourself.

I'm not sure to what specific beats you've been listening to but they surely did "work". I listened to a few hemi-sync beats some time ago (http://www.hemi-sync.com/) and they've brought me the worst nightmares I've ever had. On the next they I got sick. I've also talked to people who said they've had OBE (http://en.wikipedia.org/wiki/Out-of-body_experience) after listening to those beats. This never happened to me though. Just the nightmares. I guess it really depends on your current state, in what frequency these waves put your brain in, etc. So it's highly individual.

What do you mean by "work"?

Are you unable to hear the "warbling" variation at the frequency difference rate? Or are you expecting some meta-physical woowoo to happen just 'cause you're listening to it?

I hear the "warbling", but I don't get sleepy or dizzy or whatever the described effect is it.

OK, same here.

Suspect sounding claims with pseudo-science-y sounding justifications/explanations – I wasn't even interested enough to check whether I was effected that way.

I have used brainwave entrainment before, to aid myself in meditation and to help me visualize. It did help me feel that I got into more of a meditative/trance state while using them, but sometimes it worked too well and I fell asleep (it doesn't help that I meditate lying down in my bed).

When I actively used stuff like that (many years ago), I had the impression that bineural beats in particular weren't useful. However I tried to Google it and I wasn't able to easily confirm my memory, so I guess it's up in the air for me.

The UAE has banned some of the aps. Thats what finally got me to try them out.

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