Freesound Forums
binaural beat as content
Started June 20th, 2011 · 19 replies · Latest reply by AlienXXX 6 years, 2 months ago
Binaural beats are the case, when two frequencies interfere, and produce third tone, which is a difference between them.
fb = |f1 - f2|
But... I have the "fb signal"; it is not a "single constant frequency", but "timeline signal". This fb signal - I'd like to get as a "binaural result" of two tones/frequencies (f1 and f1) interference.
Does anybody know, how to manipulate f1-signal and f2-signal in order to get the third (fb) virtual and irregular tone? And how to make it both sides (neither f1 nor f2 constant; rather move them in relation to center between them)?
In spectral It would be like so:
-----------------
f1 upper range
f1 lower range
-----------------
dynamic binaural content
[and (f1+f2)/2 center]
-----------------
f2 upper range
f2 lower range
-----------------
Plus perhaps the "center" movement according to some algorhithm or other carrier.
I know, that the depth of fb is limited.
I'd like to get f1 and f2 signals as separate wave files.
This might be helpful:
http://www.sfu.ca/sonic-studio/handbook/Combination_Tones.html
http://www.faculty.ucr.edu/~eschwitz/SchwitzPapers/TitchDemo030417.htm
I'm looking for a software solution, some generator or vsti plugin or synth (with "how to"
.
pitch of one, single freq voice would change down,
and pitch of second single freq voice would change symetric up,
center between two pitches - selected by user.
Ring modulator ? ... http://www.freesound.org/samplesViewSingle.php?id=114457 
ayamahambho
I'm looking for a software solution, some generator or vsti plugin or synth (with "how to"pitch of one, single freq voice would change down,
and pitch of second single freq voice would change symetric up,
center between two pitches - selected by user.
Try this...
You need a VST synth with two oscilators and an LFO and which is capable of playing at very low octaves.
1) set osc 1 to sine wave and osc 2 to sine wave.
2) Set pitch modulation to +x% on osc1 and -x% on osc 2 (you will have to work x out to give you the frequencies you are after).
3) Center freq will be determined by the pitch of the note played.
4) switch off filters and effects on the synth, if any. Set the amplitude envelope to your preference (you will provavly want fasta attack, no decay and 100% sustain and then play looooooooong notes).
Good luck !!!
This one seems easy to use, probably at the expense of possibilities for the carrier tone.
If you want to process a sound from any source you might go this way and experiment with the Shift parameter; in this case, your sound would directly be one of the channels and not the center.
Either I did not understood something, or must clarify something else (-;
I don't wan't to create "whatever binaural" between two tones. I'd like to put there concrete wave file, which will result as a binaural/virtual content.
It's like this:
Input "wave file" for binaural content is in range 0-100Hz or a little bit more.
Center frequency would be for example 400Hz (or is defined as a noise range between 400 and 500Hz or by some other algorhithm; floating center so to speak)
Two audible signals are used (one below 400Hz, another above 400Hz, both moving symetric to the center point, but according to the input "wave file".
Input wave file is translated into something, that exist only as a binaural (differential) information.
What I'm missing?
(-:
Hi ayamahambho
OK, I admit I missunderstood your request (or something was missing initially).
I thought you wanted to create a binaural beat which would comply to a certain intended 'format' and/or 'rules' and produce a certain intended 'result'.
If I now understand your request correctly, you want an input wave file to drive a 'binaural generator' to produce the intended results. The difference from my previous understanding being that you do not want to fiddle with knobs on a VST or to have a LFO driving the 'binaural generator'. You want the 'program' to come from a wave file that you feed as input to the 'binaural generator'.
To my knowledge, no existing VST or standalone software synth does this.
This is something that you may be able to create in a modular environment (try Buzz Machines) or more likely will need to be programed from scratch (try SynthEdit or SynthMaker).
If this sounds too complicated or you do not want to try to build your own VST to produce the binaural output, you can still achieve a similar result... Instead of a wave file as the input you can try to use the method I suggested initially and are willing to program the "input file" as pitch automation on your DAW... or if you can find a sequencer or envelope generator where you can program a pattern for the desired behaviour and use it to drive the VST synth setup as I suggested.
I am sorry if these methods are all somewhat complicated, but the effect you are trying to achieve IS complicated and not already cathered for in any VST that I know.
If you do set this up, I would be very interested to see any samples of the results that you care to post on Freesound.
Thanks for advices.
I'm not familiar with these environments, so I don't know how it will go.
But perhaps someone is interested to build such virtual machine?
I'm curious too how it would sound, and to what degree such virtual/differential sound can be made.
combining f2 and f1 can give you the impression of |f1-f2|, as you mentioned, but if you modulate f0 = (f1+f2)/2 by |f1-f2| (your beat freq), you get the combination of f0, f1, and f2. Given your example, if you start with 400Hz tone, you can add 500Hz and 300Hz and end up with the effect of the 400Hz being modulated by 100Hz. This is alternative approach you might consider.
As for how to do it, or do what you originally asked for, it really depends on what you've got to start with. Are we talking about pure frequencies, or arbitrary signals, here? Pure frequencies is easy. If you have just a drone (target) signal that is, say 40Hz tone, then you take your carrier sound that we also assume is a pure tone (that's all you want, really), and pitch it up or down 40Hz. Combine the original with the shifted, and voila. Software like Cool Edit Pro can do this easily, but you can also get it from any synthesizer. Analog Box can do it easily.
If you are not dealing with pure tones, then we've got some issues. I don't know if it is generally possible, but here is how I might approach it, theoretically. If you start with a target signal that is entirely < 100Hz, say, a deep bass drone or rumble, and then you want to create any sort of signal at all that ultimately creates that target as a virtual result, then you might have to change all your signals to frequency domain with FFT -- you then take any signal as your carrier, get the FFT, convolve it -- no, not convolution, something else, but I was going to say convolve it with the FFT of the drone. You have to shift each value in the carrier FFT by the frequency amount represent by each bucket of the drone FFT (times its magnitude). Not sure what you call that. We're looking for a constant shift in Hz here, regardless of where we are in the spectrum, not a linear shift by some factor. What do you call that, anyway? I think I would have to program such a thing from scratch, which is a lot of trouble.
I've done it with pure tones, but never with general signals with complex content.
I don't know if I'm helping or hurting here.
I think ayamahambho's problem is that he wants the signals to change in time.
First, f0 = (f1+f2)/2 is to remain constant at all times, so the variation needs to be created by f1 going down whilst f2 goes up by exactly the same amount.
Even this is not too difficult... if you are willing to program/automate pitch up/down effects, almost any daw and VST synth could be used to do this.
The problem is really that ayamahambho wants to input the 'program'in the form of a wave file. He wants this file to be one tone that moves up and down in freq, call it fi(t), and he wants this tone to control the movememtn of f1 and f2. Effectively he wants the generated binaural beat to match the frequency of this input signal:
fi(t) = f1(t) - f2(t)
Most VST synths can reat to virtual control voltages or midi signals, so the described effect is easy to achieve with programing / DAW automation.
But I do not know synth or effects that will react to an input signal's pitch, which would allow the construction of the effect ayamahambho is after.
I am afraid this woud require the building of a dedicated effect (using Synthedit or a similar environment), hard programing (i.e., stuff like C or other languages). Maybe it can also be constructed using MatLab or similar mathematical modelling software.
Whichever approach, it will require a significant amount of knowledge and effort.
If the purpose is simply to listen how it would sound, then it can be constructed using DAW automation.I could even offer to creae a couple of examples.
The creation of a VST or program that takes the proposed wave file as its input and generates the resulting effect is beyond my programming knowledge and the time I can spend on this. Sorry.
Well - there is more behind that, but this is step-by-step process/experimentation.
I guess, the middle frequency (to which left and right channels are related via 1st wave file) would be driven by 2nd wave file.
Thanks for tips.
Can vary the beat frequency using Audacity and a few lines of Nyquist code ... http://www.freesound.org/samplesViewSingle.php?id=123636
I used a simple sine sweep, but any low frequency signal (content below 30Hz) could be used.
Frequency-modulate one channel by the low-frequency control signal, and frequency-modulate the other channel by the inverse of the control signal.
Ayamahambho,
From reading everything, I get the feeling that you essentially want to vary the generating (high) tones pitch while retaining a binaural effect (3rd tone), but also having an option to adjust the binaural beat's frequency?
I have been using Gnaural (http://gnaural.sourceforge.net/) - I've found that even if it doesn't give you the exact sound you want, it still helps visualize the timeline that you're looking at to be re-created in your DAW. The program allows for any variation of rising / falling tones, with the binaural beat pulsing faster the further away the two generating (high) tones are from each other. You can start with a very fast binaural beat and draw an automation for the generating tone's pitch to slowly bring them closer together in frequency, thus slowing the binaural beat down... Just be careful, if the difference in the generating tone's frequency is getting down towards the >1Hz range, the binaural beat slows to the point where it can appear to be in only one ear at a time.
I've made some with generative tones other than sine waves, you can still get good results but it can slightly change the feel depending on your waveform. Try creating the basic tone (Sine / Triangle / etc) and add some very slight modulation or combining waveforms, being careful about anything too crazy- multiple detunes/stacked oscillators, I found it detracts from the effect somewhat.
Remember that panning makes a big difference too: Ex - 400Hz (hard left pan) & 398Hz (hard right pan) would roughly make a 2Hz binaural beat. The harder the panning, the more pronouced the binaural beat appears. At least in my experiments.
Googling around may warrant other programs, but Gnaural has been satisfactory for my goals. Be REALLY careful if you come across BrainWave Generator (www.bwgen.com)- I never got around to installing it because Kaspersky security said it detected Spyware / Trojan.
(Appologies if the numbers are not 100% accurate, etc. I'm not near my studio PC 
)
Hope this may be of some help!
Regarding binaural beats and other brain entrainment techniques (including my own):
http://planetaziemia.net/special-001-mtt-extreme.htm
http://planetaziemia.net/mtt.htm
- this is my level of creation and understanding of this topic.
But what I would like to create is... Hmm... An audio illusion of complex sonic structure, like "speech-filtered similar", produced from independent (stereo) sources. But the left/right sources should give no indication of what is in between.
Binaural beats are a good comparison here, because third tone is produced by the brain. I'd like the brain to produce something else (-;
p.s.: never used anything else than my old synrillium cool edit. Unfortunately - Adobe decided to remove in current 4.x version both - noise generators and tone generators, and I think - FFT filter too, but I'm not sure about the last one. While these are one of the best tools you could get there.
Problem solved.
It was a matter of understanding the signal processing.
It can be done by simple amplitude modulation plus sideband separation.
Of course the content must be limited in relation to carrier range.
Check out the free PC program SBaGen.
Just code your file like:
theta: pink/5 108+5.6/95
alloff: -
NOW theta
+00:10:00 alloff
This gives you 5% pink noise and 95% of a 108hz have that has a 5.6hz difference between the two ears.
As you can see by the bottom text, it starts the first beat listed then plays it for 10 min before shutting off.
You can just add times and more data to the list to make it change throughout the sequence.
You can right click your *.sbg file and "write to wav" then blend into your song in a DAW.
Hope you find this an easy solution.
-OzeroniX
This post just 're-surfaced'...
Summarizing what has been said:
The binaural beat is the illusion of a third frequency when 2 frequencies are combined. Typically this is done with sine waves.
You can get this effect by playing two sustained notes next to each other on the keyboard. The sound is unpleasant. It has a chirping to it at high frequencies, in the lower octaves you can ear it as a wobble.
If the two signals change in frequency (e.g.) modulated by an LFO, you can get this binaural beat to change speed. for low frequency sounds this would sound like: wooob - wooob - wooob - wob -wob - wob - etc...
Actually, ayamahambho's request went a bit further, and can be translated like this:
I want a complex signal to modulate the two frequencies (F1 and F2) so that the illusory frequency (F3) evolves in a complex way.
This is easy to achieve if you use Reason. As follows:
1) Load an instance of the Thor synth
2) Load a sampler and load into it the sound you want to use as modulation source.
3) You don't have to, but makes everything much easier if you put the Thor and Sampler inside a combinator. - this beacue the same midi will be fed to both instruments simultaneously
4) Re-route the left output from the sampler to "Audio in 1" on the Thor. Discard the right output from the sampler (you could actually do stereo modulation, but I will use mono for my example)
5) Reset the Thor, then set OSC1 and OSC2 on the Thor to analogue sine wave. Switch off envelopes and filters
6) You will need the modulating signal to be much lower frequency than the signals being modulated. If not, it will greatly distort the 2 frequencies from sine waves (frequency modulation) and introduce lots of unwanted frequencies.
You can achieve this by lowering the tuning on the sampler by a 2 octaves OR by setting an aggressive Low Frequency filter, or a combination of both.
You also need to raise the tuning on the Thor oscillators by a couple of octaves.
7) In the modulation matrix assign 'Audio in 1' to modulate 'Osc 1 frequency" by 'x', also assign 'Audio in 1' to modulate 'Osc 2 frequency' by '-x'.
8 ) Play some notes on the keyboard. - Warning: The sounds produced are unlikely to be pleasant!
9) adjust 'x' to taste.