This one is, admittedly, a bit of a risk. It relies on y'all hearing some things that can be pretty tricky to hear. If you can't pick it out, there may be a couple things to try: 1) It might be too quiet. Combination tones are inherently softer than the generating frequencies, so if those aren't playing loud enough, then the combination tones will be below the threshold required for perception. Turning up your volume might help, although of course don't do anything that could damage your hearing. 2) It's possible that the sound system you're using isn't high enough quality to play the isolated tones without additional background noise. If that's the case, maybe try another set of headphones or speakers if you have access to them? 3) They're just hard. Especially if the generating frequencies aren't moving, it can be difficult to actually identify the combination tone. That's why I started with the white noise example: All that chaos in the generators makes the relatively-stable combination tones stand out. It might be worth just listening to it a few more times to see if you can find them: Once you do they actually stand out quite well. If none of that works, I'm sorry. I promise they're there. I ran these by some non-musician friends and they were able to hear them a bit, so it shouldn't be impossible, but in the end it might just not work for you, especially if you don't have access to good audio equipment. Still, though, even if you can't hear them yourself, I think knowing about them is pretty interesting!
12tone in physics two opposing waves (in this case sound) of slightly different frequencies (for example a difference of 200hz) will interfere in alternating patterns of constructive and destructive interference. This is called a beat. This is why two very close but not quite in tune notes have audible "waves" or beats. So when you play two sine waves with a known difference between their frequencies (i.e. 200 hz) the resulting beat frequency (the difference tone) is heard.
Hey, thanks this is some edgy information! You might also like to do a video on Terzi Suoni which is the third note that appears above two notes played in an interval. It's easy to make them on my viola in higher positions and the notes are always complimentary to the interval in a major or dominant way (completing a major triad or dominant 7th).
12tone I've first noticed combination tones in a record sessions about ten years ago, as drummer of my former band. My part and the bass was already done but I was in the studio when the guitars were being recorded and I could hear these strange harmonics, at the time I was really young had no clue about this, my thoughts were there's some mic positioning issue or we needed to adjust the distortion a bit, but it wasn't the case. This is for real, I would say it's even clearer if the music is live, in this situation the sound equipment was awesome so yeah that helped a lot. I think your channel is great man, to share your knowledge and approach on music, witch is limitless and we don't quite get it yet, it's something, thank you.
I'm a private lessons instructor, and I regularly give saxophone lessons. I usually can't play with my student much because if we're harmonizing certain pitches I will hear _very_ strong fundamentals in my left ear, which are loud enough to cause me pain. The most prominent one I hear is when we are playing G4 and Bb4, and I hear a very, very low Eb fundamental. Crazy stuff!
This happens to me as well. It's so physically painful in my jaw and head, and I feel so nauseated when I hear them, plus the combination notes are so loud that I can barely hear the fundamentals, that I have to deliberately play slightly out of tune to stop the effect when I'm playing duets with people on violin or clarinet. I haven't met anyone else apart from my child, who is similarly physically repelled by the sound before, so this is very interesting.
Guitarists exploit this all the time: do a unison bend and move the bent string in and out of tune with the fretted note you are in unison with. You’ll hear the difference tone/beat frequency. Works best with a load of fuzz to get some crazy subsonic oscillations.
This is a really interesting effect that seems to be linked to beat frequencies. When two sinusoids are played together, or summed, the result is a new sinusoid that is enveloped by a sinusoid at the difference of the two initial frequencies. Ie, cos(A) + cos(B) = 2*cos(A/2+B/2)*cos(A/2-B/2). This causes the new sinusoid to fade in and out at the difference of the two initial frequencies, and is the principle at play when you tune an instrument from harmonics. What's interesting is that you can still hear the beat frequency if you just play two different sinusoids panned hard left and right. If you listen to the same two sinusoids panned to the center the beat is very clear, but with them panned hard left and right it is much more subtle. Physically, it's not there but our brain is filling it in. I'm not a neuroscientist, but it seems like our brain is filling in that beat frequency based off what it expects when it usually hears those two frequencies together.
Keep in mind that beat frequencies are really easy to "make real" by accident. While two pure sine waves together will not contain the difference tone itself in a perfect system, the moment you introduce any non-linear imperfection (e.g. distortion), the difference tone becomes real. You can try this out yourself in e.g. Audacity. Just mix together two frequencies, plot the spectrum (it'll be clean), then use a non-linear effect like "Valve saturation", "Valve rectifier", "Diode processor" or "Hard limiter" and plot the spectrum again. The difference tone will show up very strongly. Without our brain getting involved (when the two frequencies aren't hard panned), I bet the basic physics of our ear introduces non-linear distortion sufficient to bring out the difference tone. In fact, this is how radio tuners work. If instead of adding together the two frequencies you *multiply* them together, you actually get the difference as a result. Tuners work by generating a reference frequency and multiplying it by the input signal. The result is a frequency-shifted version of the original radio signal.
That was absolutely cool! After you explained it at the end I heard it and had to go back to the beginning. It's very low tones but after the end of the video they can be heard without head phones too. Probably because we are now knowing what to expect.
I can only hear them on the highest pitched part of the slide but that reminded me when I was young my sister and I would scream really high pitches together (must have been horrible for everyone else) because it created this lower unexpected pitch.
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
I think the fact that it's caused by a difference rather than a combination of overtones is due to the pure shape of the wave rather than the brain calculating overtones down to a fundamental. When you play the 1100Hz an 1300Hz sine waves together they form a pattern that repeats 200 times a second due to that difference, and therefore a 200Hz pattern, which our brain picks up on and hears as a separate note.
When I play a note on the pitch pipe app on my phone, and hum another note, I can sometimes hear a fundamental in my ear. I know it's not there, but I can hear it loud and clear. It's really weird, but strangely fascinating!
Thank you so much for making this video!! Sometimes in choir I get overwhelmed because I will start to feel this odd (previously indescribable) sensation where I, like, “/feel/ a sound” if I’m really in tune with the person next to me and we’re singing really high (this happens more when I’m singing with one other person). I think I’ve been feeling combination tones? The notes go by so fast so I don’t have time to identify the pitch, so it just feels CRAZY for a second and then it’s over. When you played the static with the melody under it, I heard it SO clearly and I physically FELT it in my ears. Is that possible? It feels like it’s such an odd and distinct feeling from hearing generated tones that actually exist.
I wonder if this is actually useful for anything, except for being awesome. Makes you think how much of music is our brains acting weird when exposed to different frequencies of sound. Great video!
Sergej Bozinovic Don't know much about general music, but in Heavy Metal, playing fifths ("power chords") on a distorted electric guitar is a very common component of the music. If you play the root, but instead play the fifth one octave lower than it should (an inversion) you can create the illusion that there's a root note being played 1 octave lower, way below what the guitar tuning is capable of. Modern metal bands commonly use this technique to sound much 'heavier' without needing to lower their guitar's tuning.
iau I wasn't aware of this. It's quite interesting and makes sense now that I think about it. I know that a lot of church music(at least orthodox Christian) uses power chords frequently, probably the echo and distortion of sound in a church create a similar effect. Leave it to metal to make something holy into something heavy I guess. I also researched a bit and found that some earbuds use this to create sounds for which the earbuds are too small to create without the "extra sounds". Thank you for your comment, kind and knowledgeable stranger!
Interesting sidenote: I originally stumbled onto this topic while reading a paper on heavy metal harmony and the impact combination tones have on power chords. I'd heard of them before, but that was when I decided I could probably do a whole video on them.
I have a pretty mild tinitus and think this actually helps me hearing the differentiation tones... I've heard them since i was about 14 yo but never really got a responce from other people when I described the sounds. I described them as rubbery sounds that I heard in certain parts of some songs... For example in the Flower Duet from Lakme, the tones make a memorable appearence at one particular point in the song. I Always thought it was something only I was hearing. Blew my mind bro, thanks for giving me this peace of information!
That's really interesting! I would've thought tinnitus would interfere with hearing them, since it introduces another tone your brain has to process, but I guess not. Thanks for sharing!
What's crucial to mention here is that combination tones are mostly an artifact of _nonlinear processing_. That's why they're so evident in electric solo guitar (distortion is completely nonlinear), and also when singing into a flute or trombone. In most other situations, nonlinearities are avoided as best as possible. A perfect computer realisation of 1000 Hz and 1200 really does *not* have any difference- or sum frequencies. But to make such a signal actually audible, you need to pass the signal through an analogue amplifier and speakers, and these can't be 100% linear (it would require infinite engineering precision, as it were). The ear itself isn't perfectly linear either. On any _good_ speakers, the nonlinearities are small though. They are easier to hear on _bad_ speakers. Mind, this is a bit a matter of definition: one could argue that for a signal consisting of 1000 Hz and 1200 Hz summed together, 200 Hz is the _only_ frequency. After all, this combined signal is neither periodic after 1/1200 s nor after 1/1000 s, but it is periodic after 1/200 s. But, that's clearly not how our ears perceive pitch. What we perceive is mostly the Fourier spectrum, and in that spectrum, 200 Hz only turns up after nonlinear distortion.
On a guitar in standard tuning, play the A and D strings together. You will hear a much lower D note at the same time. It's what piqued my interest on this subject.
WOW at first I played the video at a normal volume, and didn't hear anything, I thought this was too difficult for me or whatever, BUT I turned the volume up (which I should have done in the first place) and I heard it ! I thought I had to really concentrate on the sound, but my brain did its work so I heard it without forcing. Great video !
That was mind bogglingly awesome! :O 12tone, thank you so much, your impressive videos are so profoundly good, I feel that I am learning something new every time I watch them :)
Sick, mate. I heard the difference tone melody as clearly as daylight. It sounded just like the bass in normal music. Edit: I did not hear the sum tone though :D
Sum tones are REALLY hard... I had to listen to that example like four or five times, holding a 900hz sound in my head while I did, before I could convince myself I was actually hearing it. It's really faint, and it's covered up by the relatively close generating frequencies, but it's there!
bruuhhh combination tones are literally a physical phenomenon and not an illusion, the undertone is found in the periodicity between the two ringing tones. think of it like a polymeter: you have a sequence that takes five beats to wrap up playing simultaneously with a sequence that takes four beats: they start at the same time and their beginnings meet again after 20 beats.
That's all true, but I'd argue that, in order to be described as an actual physical phenomenon, the frequency would have to exist within the spectral analysis, and it doesn't. According to my research, combination tones exist due to non-linearities in the inner ear that allow us to pick up on patterns that aren't actually components of the played note, and thus I think it's reasonable to view them as a psychoacoustic phenomenon rather than a physical one.
12tone then how do you explain the fact that when one of the tones comes solely to your left ear and the other to the right the combination tone is inperceivable
I haven't tried the experiment myself (I'm still learning how to use this sine wave program so I haven't figured out panning yet.) but my research indicates that it isn't, it's just quieter. In fact, another commenter on this video made the explicit claim that they could hear the combination tone in that exact scenario, although they described it as "much more subtle". A related phenomenon is binaural beats, which explicitly rely on dichotic listening and seem to have a lot of supporting research indicating that it exists.
A different sine wave in each ear generates "subjective beats" which is a big topic. It's possible to hear them even if one of the tones is too faint to be audible. People use it for brain wave entraining. This was all discovered in the 1960's and 70's and is easy to demonstrate with two sine wave generators and headphones. The beats can be at very low frequency, so they sound like tremolo.
Wow, that was fantastic! It's so crazy how good the human brain is at making up stuff and filling in the blanks. It sort of makes you wonder what else we're just "filling in" on a regular basis. (By the way, the brains looked great! 😜)
Thanks! I realized halfway through the process that it might've been a fun topic to collaborate with y'all on, but by that point I was too far into it already... Ah well, there's plenty more psychoacoustic phenomena out there!
It's not in your brain, it's in your *_eardrum_* . If you use headphones to pan the two tones with no crosstalk, no matter how loudly you play it, you won't hear the third tone. Increasing the volume under normal listening conditions doesn't increase the volume of the phantom tone, it increases *_production_* of the phantom tone by vibrating the eardrum harder. You can verify for yourself at szhorvat.net/pelican/combination-tones.html where the test tones are hard-panned in stereo. Through speakers you can hear the phantom tones, especially in the sliding-tone test, but through headphones...nope, at least not with sine waves (see footnote 2). The brain does not create the phantom tone...the tone is really there.
nothing i already didn't know except for the more math bits, it can be easier to hear with reverb added in, and i even created a sine wave arpeggio in a song be because i heard it while composing which may be because of timbre, just thinking outloud.
the tones are quite a bit louder than your voice. I figure you are careful about these things, so this is by design. But, I figured I'd mention it was painful for me to listen to the shifting tones section and that made me turn it down for the rest of the video.
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
Playing high F and B and seem to hear both a D and a G#? Is that the sum + the difference both being in easily ''audible'' range? Is it my terrible speaker resonating it's casing? Never felt so uncertain making music haha. Also, seems you get a major triad in third inversion if you play a sharp 5, I'd love to see this used
I can hear the Mozart melody now! I had understood that the low ghost Mozart melody was the frequency difference between two lines being played together over time. But then this sentence confused me, "This creates a constant difference tone even though the actual played notes keep changing." By "constant" do you mean "same tone?" I thought the "difference tone" WAS the Mozart melody. Maybe by "constant" you just meant continuous sound over time (but playing the ghost melody). ?
There are clips that demonstrate this better, generally of lower speech on land line telephones, which can't actually reproduce the fundamental for such low notes. I wish I remembered the scholarly set of online articles I learned this from.
Hey 12tone! I'm quite late to the party, but don't you have any idea, why I can hear combination tones (both low and high, with volume loud enough) in your video clearly, but can't hear any in "Maryanne Amacher - Sound Characters". Can you hear them I also hear other tones when overdriven guitar plays, let's say, D and E on in higher register simultaneously and bends the D towards E... Does it mean that they aren't there too? Because I think I can feel them in my body.
How did you create the Combination Tone? that part got me interested and it went fast ;p So you did this in a DAW software like FLstudio and wrote a melody first or created that white noise, if so how did you manage to create the white noise? is that additional plug in? Thank you and i really know i am asking too much but my hunger to know and the curiosity got the better of me. Thing is i wish to compose music and harmonics using this. Thank you once again and forgive my utter rudeness to ask so much of what you already are and will share.
They were made with a program called SuperCollider. The code I used was based on the stuff from this article: earslap.com/article/combination-tones-and-the-nonlinearities-of-the-human-ear.html
In the topic of combination tones, obviously not combination tone itself but i wish to use this opportunity to dedicate something for you, speculator artist. Enjoy, ruclips.net/video/dO12h46EOyQ/видео.html Thank you once again, Its just the fact that i am struggling to get a job once there I a;ready considered myself becoming a Patreon.
Sorry to dig up an old post, but just stumbled upon this naturally as I was working on some music. Can you elaborate on it being all in your head? Interestingly enough, I'm actually seeing these frequencies present in spectrums/spectrograms/etc, so it seems to me as if they're actually frequencies that are produced and not just something internal to your head?
I'm always concerned with 'pure' sine waves. The longer I listen to them the more convinced I become that I can pick out the harmonics. My interpretation of this is that in any realistic setting ( office, bedroom, sitting room and even studio) there will be sympathetic vibrations that will add to the tone. These may even originate in the speakers themselves (since the amplitude is highest there as well). So really I doubt that there can be a real pure single-frequency tone that we can experience if it is not produced in a quiet room where no objects can resonate with the source. Also, I'm pretty certain that the complex materials of real life will modulate the tones, leading to anharmonicity and even beating that it's heard even when a single frequency is being played.
True, true. I suppose "pure" is probably an overstatement. In the case of sine wave generators, though, those harmonics are very quiet, at least, so even though they're probably there in some capacity, they're not getting in the way all that much. They're not pure, but they're the closest we can get.
I think there is more to the physics of that. When you play two notes at the same time they'll make the air vibrate at their respective frequencies wich will overlap and interfere. If you graphicly add those two notes they'll produce a kinda weired looking mumbo jumbo, but if you pay close enaugh attention to the notes you'll see the difference in pitch. I'll link a picture real quick: imgur.com/a/6gVfP
I don't know if this is just me but the non existing note in the end of Mozart's melody sounded a bit detuned, it was recognicable as the fundamental but it was a bit off, Is my brain detuned? How can my brain pick up the detuning of my own brain?
I'm just not hearing it at all. I turned up my volume, am using pretty high quality headphones and listened multiple times. I can't hear the tones at all.
Hmm... I'm not sure what else to recommend. Unfortunately, they can just be really tricky to pick out. I find the white noise example to be the easiest so that's where I'd focus on first. It might especially help if you did the one at the end, so you hear the "real" version of the melody first and then try to explicitly listen for that. Beyond that... I don't know, sorry!
Neither can I. I read about Tartini tones before and I knew what to look for... And still didn't hear it. I used decent headpones, played at comfortable volume, and nothing. But I wouldn't say that it's bad. This effect bases on the way our brain processes information, so anything can happen depending on a person - from not hearing at all to hearing clearly. So, our case proves the point - other people hear tones that aren't there :)
sihplak Here is a little tip for you: when you hear these weird noises try to sing the melody that you should hear in your head as if it's there. That will help your brain to find the melody in these weird noises. Sorry for bad english i hope it worked out for you.
For me, it sounded like the melody wasn't really coming from my speakers, but from "inside my ears". Try this if focusing on different parts of a soundstage helps you pick sounds out like it does for me.
Cool videos man, but watch out with those pitches volume, especially using headphones. Isolated frequencies above 1khz can be really harmful for your hearing, in fact many factory workers are exposed to machinery that resonates around a 1khz peak and being constantly exposed without protection will consequently develop an attenuation around that freq over time (sorry, not a native english speaker).
What happens, if I hear this two different tones separated stereo each in only one ear? It reminds me of binauralbeats, where I don't hear the "ghost tones" but my brain wave starts moving in this difference.
This is known as beating. You say the note isn't there, but it actually is. If you look at a scope, you can actually see the two notes form a beating freaquency; that is what you hear. In fact power chords on guitar are a prime example if a beating note, with the first and fifth creating a very pronounced note one octave below the root. FM synthesizers also exploit this principle to build complex sounds.
Okay, that's just freakish... At first, I couldn't hear anything but garbled, alien-like noises, kinda what I would expect to hear at a Karaoke club for R2 droids. Then I heard your explanation and tried again with better headphones, and I could actually faintly hear that Mozart-melody... It's vague, but it's there... Except it's not there... And yet it kinda is?
Hello! This is very interesting, I didn't know about it. However, you played loud unpleasant sounds that I had not enough time to anticipate with the pacing of the video which also sounded louder than the speech. That made watching this video pretty unpleasant for me and I think you may have needed to give that more consideration though I guess many people are less sensitive to such things. Good luck!
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
Thanks for paying attention to my criticism and replying. Of course, apology accepted. I appreciate you took volume into account but I think the unexpected timing was more significant. I watched another of your videos and I realize the fast pace is part of your regular format but I think that in this video it may have been a significant part of what created the unpleasant effect. Maybe it would have been better if you had a warning and a pause before each of these sounds. Also, your videos seem pretty interesting, I subbed.
I am using headphones and I know that these effects are real. But sadly I wasn't able to hear any of the sum tones. Or most of the difference tones. I did make my own overtone series though and I usually couldn't hear the difference tones without at least 3 sine waves. At least at the distances from the fundamental similar to those in the video. Maybe my hearing is just bad. Edit: On a second watch through at higher quality, I was able to hear the 900Hz sum tone.
Yeah, the sum tones are really, really hard to pick out. I had to try it four or five times, relistening to the 900 first every time, before I could convince myself I was actually hearing it.
It's actually not really in your head, if you have two sine waves added together, they can be written as the sum of the two frequencies as an overtone of the difference!
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
I suspect it has to do with your headphones. I found out after putting this out that some portion of the tone is actually manifested in the signal due to distortion, so if your headphones don't have a strong low end it's possible that you're losing that part of it, making it harder to hear.
I absolutely love your channel, everything about it, your theory, communication style, everything ...but your explanation of the base Tartini Tone here is outdated by about 40 years. Dr. David Kemp proved in 1978 that "otoacoustic emissions", intermodulation distortions, actually occur on the basilar membrane. For decades now, the field of medicine has sent two tones, just like in your example, into the ears of infants with two isolated speakers and a microphone on a same probe to detect the "echo," in order to capture and analyze one of the higher distortions (than the tone you describe here.... Two isolated speakers are used to help insure the distortion doesn't occur before the sound leaves the device because that, too, can be problematic. Your "signal chain" in your computer software might tell you one thing is happening, but by the time the entire signal makes its way through all the circuitry to the final computer output...a distortion may still occur electronically. Two isolated speakers, one for each tone entering a single ear, help insure that is not occurring....because intermodulation distortions are a phenomenon that doesn't just occur with acoustics. It occurs with radio waves and electronics as well, and the basic math is the same.) But researchers and physicians still see the distortion tone you're describing (f2-f1) all the time as well, in the ears of humans and dozens of other species. Otoacoustic emissions is a deeply researched subject since Dr. Kemp...and combination tones are part of that. Point is that f2-f1 isn't being "created by the brain." It's an actual vibratory distortion on the basilar membrane itself. In 2020 researchers in Oregon even saw the 4f1-3f2 distortion on the reticular lamina (parallel to the basilar membrane). In other words, they're finding more difference tones now than they were 40 years ago with refined methods. The Music Pedagogy world seems to be catching up slowly. All that said, your channel here ROCKS. I learn new things from you all the time when I pass by this channel, and I really appreciate you putting it up.
Yeah, they're pretty faint. I didn't want to make it too loud, though, to avoid blowing out people's ears unexpectedly. Glad you could get it to work, though!
What software did you use? I want to run some experiments. Any software that can receive an input of hertz, and output a soundwave with those values, will work. Preferably with a timbre, but sine waves work too.
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
This one is, admittedly, a bit of a risk. It relies on y'all hearing some things that can be pretty tricky to hear. If you can't pick it out, there may be a couple things to try:
1) It might be too quiet. Combination tones are inherently softer than the generating frequencies, so if those aren't playing loud enough, then the combination tones will be below the threshold required for perception. Turning up your volume might help, although of course don't do anything that could damage your hearing.
2) It's possible that the sound system you're using isn't high enough quality to play the isolated tones without additional background noise. If that's the case, maybe try another set of headphones or speakers if you have access to them?
3) They're just hard. Especially if the generating frequencies aren't moving, it can be difficult to actually identify the combination tone. That's why I started with the white noise example: All that chaos in the generators makes the relatively-stable combination tones stand out. It might be worth just listening to it a few more times to see if you can find them: Once you do they actually stand out quite well.
If none of that works, I'm sorry. I promise they're there. I ran these by some non-musician friends and they were able to hear them a bit, so it shouldn't be impossible, but in the end it might just not work for you, especially if you don't have access to good audio equipment. Still, though, even if you can't hear them yourself, I think knowing about them is pretty interesting!
And put the volume at max (it worked for me, when it wasn't high enough I could not listen)
Thanks for the reassurance! I can't seem to pick out the difference and I was starting to question my sanity.
12tone in physics two opposing waves (in this case sound) of slightly different frequencies (for example a difference of 200hz) will interfere in alternating patterns of constructive and destructive interference. This is called a beat. This is why two very close but not quite in tune notes have audible "waves" or beats. So when you play two sine waves with a known difference between their frequencies (i.e. 200 hz) the resulting beat frequency (the difference tone) is heard.
Hey, thanks this is some edgy information!
You might also like to do a video on Terzi Suoni which is the third note that appears above two notes played in an interval. It's easy to make them on my viola in higher positions and the notes are always complimentary to the interval in a major or dominant way (completing a major triad or dominant 7th).
12tone I've first noticed combination tones in a record sessions about ten years ago, as drummer of my former band. My part and the bass was already done but I was in the studio when the guitars were being recorded and I could hear these strange harmonics, at the time I was really young had no clue about this, my thoughts were there's some mic positioning issue or we needed to adjust the distortion a bit, but it wasn't the case. This is for real, I would say it's even clearer if the music is live, in this situation the sound equipment was awesome so yeah that helped a lot. I think your channel is great man, to share your knowledge and approach on music, witch is limitless and we don't quite get it yet, it's something, thank you.
I'm a private lessons instructor, and I regularly give saxophone lessons. I usually can't play with my student much because if we're harmonizing certain pitches I will hear _very_ strong fundamentals in my left ear, which are loud enough to cause me pain.
The most prominent one I hear is when we are playing G4 and Bb4, and I hear a very, very low Eb fundamental. Crazy stuff!
Wow, that's really interesting! thanks for sharing!
Do you recal having tinitus in your left ear by any chance?
Are those concert pitches or the transposed pitches?
This happens to me as well. It's so physically painful in my jaw and head, and I feel so nauseated when I hear them, plus the combination notes are so loud that I can barely hear the fundamentals, that I have to deliberately play slightly out of tune to stop the effect when I'm playing duets with people on violin or clarinet. I haven't met anyone else apart from my child, who is similarly physically repelled by the sound before, so this is very interesting.
Guitarists exploit this all the time: do a unison bend and move the bent string in and out of tune with the fretted note you are in unison with. You’ll hear the difference tone/beat frequency. Works best with a load of fuzz to get some crazy subsonic oscillations.
Right. Distortion is in fact what brings out the difference- and sum frequencies. It's a _heterodyne_ to name the technical term.
Don't forget power chords!
Thats so weird! At first I couldn't hear anything but after finishing the video i went back to the start and I heard it
Crazy, right? For some of them I had to try four or five times before I could pick it out, but once you do it's awesome.
It's easier to pick out something when you know what's coming ^_^
This is a really interesting effect that seems to be linked to beat frequencies. When two sinusoids are played together, or summed, the result is a new sinusoid that is enveloped by a sinusoid at the difference of the two initial frequencies. Ie, cos(A) + cos(B) = 2*cos(A/2+B/2)*cos(A/2-B/2). This causes the new sinusoid to fade in and out at the difference of the two initial frequencies, and is the principle at play when you tune an instrument from harmonics. What's interesting is that you can still hear the beat frequency if you just play two different sinusoids panned hard left and right. If you listen to the same two sinusoids panned to the center the beat is very clear, but with them panned hard left and right it is much more subtle. Physically, it's not there but our brain is filling it in. I'm not a neuroscientist, but it seems like our brain is filling in that beat frequency based off what it expects when it usually hears those two frequencies together.
Really interesting! I'd read that about panning, but I hadn't actually tried it yet. I'll have to give it a go!
Keep in mind that beat frequencies are really easy to "make real" by accident. While two pure sine waves together will not contain the difference tone itself in a perfect system, the moment you introduce any non-linear imperfection (e.g. distortion), the difference tone becomes real. You can try this out yourself in e.g. Audacity. Just mix together two frequencies, plot the spectrum (it'll be clean), then use a non-linear effect like "Valve saturation", "Valve rectifier", "Diode processor" or "Hard limiter" and plot the spectrum again. The difference tone will show up very strongly.
Without our brain getting involved (when the two frequencies aren't hard panned), I bet the basic physics of our ear introduces non-linear distortion sufficient to bring out the difference tone.
In fact, this is how radio tuners work. If instead of adding together the two frequencies you *multiply* them together, you actually get the difference as a result. Tuners work by generating a reference frequency and multiplying it by the input signal. The result is a frequency-shifted version of the original radio signal.
I made some graphs that should show whats going on with the adding frequencies stuff, feel free to use those
imgur.com/a/6gVfP
4:50 And remember, ＩＴ＇Ｓ ＡＬＬ ＩＮ ＹＯＵＲ ＨＥＡＤ
I ain't happy, but I'm feelin' glad...
That was absolutely cool! After you explained it at the end I heard it and had to go back to the beginning. It's very low tones but after the end of the video they can be heard without head phones too. Probably because we are now knowing what to expect.
Anyone else throw their headphones out their ears when you heard that 200hz tone?
That was the coolest thing I've heard in a long time! It's like the ghost notes are buzzing from within my ears haha
I know, right?
That’s because they literally are.
I can only hear them on the highest pitched part of the slide but that reminded me when I was young my sister and I would scream really high pitches together (must have been horrible for everyone else) because it created this lower unexpected pitch.
Woah, really cool! It's awesome that you were able to find that combination tone with just your voices.
Volume Warning @ 3:07
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
Yup that's when I had a heart attack lol
I wish I had paid more attention to this
I think the fact that it's caused by a difference rather than a combination of overtones is due to the pure shape of the wave rather than the brain calculating overtones down to a fundamental. When you play the 1100Hz an 1300Hz sine waves together they form a pattern that repeats 200 times a second due to that difference, and therefore a 200Hz pattern, which our brain picks up on and hears as a separate note.
When I play a note on the pitch pipe app on my phone, and hum another note, I can sometimes hear a fundamental in my ear. I know it's not there, but I can hear it loud and clear. It's really weird, but strangely fascinating!
Thank you so much for making this video!! Sometimes in choir I get overwhelmed because I will start to feel this odd (previously indescribable) sensation where I, like, “/feel/ a sound” if I’m really in tune with the person next to me and we’re singing really high (this happens more when I’m singing with one other person). I think I’ve been feeling combination tones? The notes go by so fast so I don’t have time to identify the pitch, so it just feels CRAZY for a second and then it’s over. When you played the static with the melody under it, I heard it SO clearly and I physically FELT it in my ears. Is that possible? It feels like it’s such an odd and distinct feeling from hearing generated tones that actually exist.
I didn't hear the Mozart at first, but now when I listen to it again it's the dominant line! This is insane.
@12tone, big thanks for clear explanation. I wanted to understand combination tones for some time now.
My violin produces super loud combination tones, it's absolutely amazing ^^
This is literally the coolest thing!!! I love your channel! All this super nerdy stuff makes me really happy!
Aw, thanks!
I almost gave up, but after listening to the sample about 8 times at ever increasing volumes I finally heard it. Cool stuff man. Keep it up.
Thanks, glad you got it working!
This is so cool. I may be wrongly categorizing this video, but I'd love to see more psychoacoustic phenomenon explained.
Thanks! Yeah, "psychoacoustic" is the right word, and it's definitely an area I want to look into some more!
Phenomena* (plural)
I wonder if this is actually useful for anything, except for being awesome. Makes you think how much of music is our brains acting weird when exposed to different frequencies of sound. Great video!
Sergej Bozinovic Don't know much about general music, but in Heavy Metal, playing fifths ("power chords") on a distorted electric guitar is a very common component of the music.
If you play the root, but instead play the fifth one octave lower than it should (an inversion) you can create the illusion that there's a root note being played 1 octave lower, way below what the guitar tuning is capable of.
Modern metal bands commonly use this technique to sound much 'heavier' without needing to lower their guitar's tuning.
iau I wasn't aware of this. It's quite interesting and makes sense now that I think about it. I know that a lot of church music(at least orthodox Christian) uses power chords frequently, probably the echo and distortion of sound in a church create a similar effect. Leave it to metal to make something holy into something heavy I guess. I also researched a bit and found that some earbuds use this to create sounds
for which the earbuds are too small to create without the "extra
sounds".
Thank you for your comment, kind and knowledgeable stranger!
I kinda figured that on my own playing my guitar, and I'm glad I can finally explain it
It's incredibly useful for learning to play in tune.
Interesting sidenote: I originally stumbled onto this topic while reading a paper on heavy metal harmony and the impact combination tones have on power chords. I'd heard of them before, but that was when I decided I could probably do a whole video on them.
I have a pretty mild tinitus and think this actually helps me hearing the differentiation tones... I've heard them since i was about 14 yo but never really got a responce from other people when I described the sounds. I described them as rubbery sounds that I heard in certain parts of some songs... For example in the Flower Duet from Lakme, the tones make a memorable appearence at one particular point in the song. I Always thought it was something only I was hearing. Blew my mind bro, thanks for giving me this peace of information!
That's really interesting! I would've thought tinnitus would interfere with hearing them, since it introduces another tone your brain has to process, but I guess not. Thanks for sharing!
tinnitus may infact generate some kind of tone of reference maybe? hmmmm.
I couldn't hear it at first, but then I turned it up really loud and I could hear it.
Nice! Yeah, they can be tricky... Did you get the sum tone? That one took me quite a few tries!
What's crucial to mention here is that combination tones are mostly an artifact of _nonlinear processing_. That's why they're so evident in electric solo guitar (distortion is completely nonlinear), and also when singing into a flute or trombone.
In most other situations, nonlinearities are avoided as best as possible. A perfect computer realisation of 1000 Hz and 1200 really does *not* have any difference- or sum frequencies. But to make such a signal actually audible, you need to pass the signal through an analogue amplifier and speakers, and these can't be 100% linear (it would require infinite engineering precision, as it were). The ear itself isn't perfectly linear either. On any _good_ speakers, the nonlinearities are small though. They are easier to hear on _bad_ speakers.
Mind, this is a bit a matter of definition: one could argue that for a signal consisting of 1000 Hz and 1200 Hz summed together, 200 Hz is the _only_ frequency. After all, this combined signal is neither periodic after 1/1200 s nor after 1/1000 s, but it is periodic after 1/200 s. But, that's clearly not how our ears perceive pitch. What we perceive is mostly the Fourier spectrum, and in that spectrum, 200 Hz only turns up after nonlinear distortion.
On a guitar in standard tuning, play the A and D strings together. You will hear a much lower D note at the same time. It's what piqued my interest on this subject.
WOW at first I played the video at a normal volume, and didn't hear anything, I thought this was too difficult for me or whatever, BUT I turned the volume up (which I should have done in the first place) and I heard it !
I thought I had to really concentrate on the sound, but my brain did its work so I heard it without forcing.
Great video !
Thanks! Yeah, volume really helps on these, the ghost tone is inherently a lot quieter than the generating ones.
That was mind bogglingly awesome! :O 12tone, thank you so much, your impressive videos are so profoundly good, I feel that I am learning something new every time I watch them :)
Aw, thanks!
Aaah, so i have to listen to it REALY FUCKING LOUD in order to hear the melody.
Yeah, they're inherently much quieter than the frequencies that generate them, so in order to pick them out you need pretty loud generators...
my volume was normal and I could hear. Is it possible we all have different levels of sensitivity to this kind of thing?
I could not hear any melody from speakers, but good headphones made the miracle! :) Thank you!
^_^
Sick, mate.
I heard the difference tone melody as clearly as daylight. It sounded just like the bass in normal music.
Edit: I did not hear the sum tone though :D
Sum tones are REALLY hard... I had to listen to that example like four or five times, holding a 900hz sound in my head while I did, before I could convince myself I was actually hearing it. It's really faint, and it's covered up by the relatively close generating frequencies, but it's there!
Same bro... Do you have tinitus in any case?
bruuhhh combination tones are literally a physical phenomenon and not an illusion, the undertone is found in the periodicity between the two ringing tones. think of it like a polymeter: you have a sequence that takes five beats to wrap up playing simultaneously with a sequence that takes four beats: they start at the same time and their beginnings meet again after 20 beats.
and then think of the beats as wavelenghts of the ringing tones and the generated undertone
That's all true, but I'd argue that, in order to be described as an actual physical phenomenon, the frequency would have to exist within the spectral analysis, and it doesn't. According to my research, combination tones exist due to non-linearities in the inner ear that allow us to pick up on patterns that aren't actually components of the played note, and thus I think it's reasonable to view them as a psychoacoustic phenomenon rather than a physical one.
12tone then how do you explain the fact that when one of the tones comes solely to your left ear and the other to the right the combination tone is inperceivable
I haven't tried the experiment myself (I'm still learning how to use this sine wave program so I haven't figured out panning yet.) but my research indicates that it isn't, it's just quieter. In fact, another commenter on this video made the explicit claim that they could hear the combination tone in that exact scenario, although they described it as "much more subtle". A related phenomenon is binaural beats, which explicitly rely on dichotic listening and seem to have a lot of supporting research indicating that it exists.
A different sine wave in each ear generates "subjective beats" which is a big topic. It's possible to hear them even if one of the tones is too faint to be audible. People use it for brain wave entraining. This was all discovered in the 1960's and 70's and is easy to demonstrate with two sine wave generators and headphones. The beats can be at very low frequency, so they sound like tremolo.
My violin is asking me to practice playing difference tones to help my intonation. This is so cool!
Wow, that was fantastic! It's so crazy how good the human brain is at making up stuff and filling in the blanks. It sort of makes you wonder what else we're just "filling in" on a regular basis. (By the way, the brains looked great! 😜)
Thanks! I realized halfway through the process that it might've been a fun topic to collaborate with y'all on, but by that point I was too far into it already... Ah well, there's plenty more psychoacoustic phenomena out there!
That's interesting, and this looks like a really good channel. Subscribed!
Thanks!
Your 40 Hz made my window shake and made me fucking shit myself
It's not in your brain, it's in your *_eardrum_* . If you use headphones to pan the two tones with no crosstalk, no matter how loudly you play it, you won't hear the third tone. Increasing the volume under normal listening conditions doesn't increase the volume of the phantom tone, it increases *_production_* of the phantom tone by vibrating the eardrum harder.
You can verify for yourself at szhorvat.net/pelican/combination-tones.html where the test tones are hard-panned in stereo. Through speakers you can hear the phantom tones, especially in the sliding-tone test, but through headphones...nope, at least not with sine waves (see footnote 2). The brain does not create the phantom tone...the tone is really there.
The most frustrating episode. I'm not hating, just dealing with my own, internal frustration. Keep on rockin'.
VERY interesting. Yes, I could pick them out.
This was a good lesson. Thanks.
nothing i already didn't know except for the more math bits, it can be easier to hear with reverb added in, and i even created a sine wave arpeggio in a song be because i heard it while composing which may be because of timbre, just thinking outloud.
the tones are quite a bit louder than your voice. I figure you are careful about these things, so this is by design. But, I figured I'd mention it was painful for me to listen to the shifting tones section and that made me turn it down for the rest of the video.
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
For me it was the other way around. I guess I just have the volume turned down lower than most people have it though.
muncs thought i was the only one ! Lol i turned it all the way down
Playing high F and B and seem to hear both a D and a G#? Is that the sum + the difference both being in easily ''audible'' range? Is it my terrible speaker resonating it's casing? Never felt so uncertain making music haha. Also, seems you get a major triad in third inversion if you play a sharp 5, I'd love to see this used
After listening to it like 10 times i was able to hear it. That's really cool :)
I can hear the Mozart melody now! I had understood that the low ghost Mozart melody was the frequency difference between two lines being played together over time. But then this sentence confused me, "This creates a constant difference tone even though the actual played notes keep changing." By "constant" do you mean "same tone?" I thought the "difference tone" WAS the Mozart melody. Maybe by "constant" you just meant continuous sound over time (but playing the ghost melody). ?
I hear it! That's so crazy!
There are clips that demonstrate this better, generally of lower speech on land line telephones, which can't actually reproduce the fundamental for such low notes. I wish I remembered the scholarly set of online articles I learned this from.
Yeah, I read some of those in preparation for this! The missing fundamental effect is wild.
Is the D at the end of the mozart quote so flat it's a Db or has my ear just gone to shit?
Hey 12tone!
I'm quite late to the party, but don't you have any idea, why I can hear combination tones (both low and high, with volume loud enough) in your video clearly, but can't hear any in "Maryanne Amacher - Sound Characters". Can you hear them
I also hear other tones when overdriven guitar plays, let's say, D and E on in higher register simultaneously and bends the D towards E... Does it mean that they aren't there too? Because I think I can feel them in my body.
How did you create the Combination Tone? that part got me interested and it went fast ;p
So you did this in a DAW software like FLstudio and wrote a melody first or created that white noise, if so how did you manage to create the white noise? is that additional plug in?
Thank you and i really know i am asking too much but my hunger to know and the curiosity got the better of me. Thing is i wish to compose music and harmonics using this.
Thank you once again and forgive my utter rudeness to ask so much of what you already are and will share.
They were made with a program called SuperCollider. The code I used was based on the stuff from this article: earslap.com/article/combination-tones-and-the-nonlinearities-of-the-human-ear.html
In the topic of combination tones, obviously not combination tone itself but i wish to use this opportunity to dedicate something for you, speculator artist. Enjoy,
ruclips.net/video/dO12h46EOyQ/видео.html
Thank you once again, Its just the fact that i am struggling to get a job once there I a;ready considered myself becoming a Patreon.
I play notes that aren't there all the time, not only with various diads and triads, but with droning pads and ring modulation.
Mind blown!
Sorry to dig up an old post, but just stumbled upon this naturally as I was working on some music. Can you elaborate on it being all in your head? Interestingly enough, I'm actually seeing these frequencies present in spectrums/spectrograms/etc, so it seems to me as if they're actually frequencies that are produced and not just something internal to your head?
I couldn't hear the white noise melody, but I did hear the phantom note in the descending tones.
Wis it possible to create triads that arent there?
Combination tones are why I dislike equal temperament. Cause if you play, say Bb and D, I hear a Bb that is sharp underneath.
I'm always concerned with 'pure' sine waves. The longer I listen to them the more convinced I become that I can pick out the harmonics. My interpretation of this is that in any realistic setting ( office, bedroom, sitting room and even studio) there will be sympathetic vibrations that will add to the tone. These may even originate in the speakers themselves (since the amplitude is highest there as well). So really I doubt that there can be a real pure single-frequency tone that we can experience if it is not produced in a quiet room where no objects can resonate with the source.
Also, I'm pretty certain that the complex materials of real life will modulate the tones, leading to anharmonicity and even beating that it's heard even when a single frequency is being played.
True, true. I suppose "pure" is probably an overstatement. In the case of sine wave generators, though, those harmonics are very quiet, at least, so even though they're probably there in some capacity, they're not getting in the way all that much. They're not pure, but they're the closest we can get.
It always drives me crazy whenever I'm tuning and I hear unexpected beating that I don't know where it's coming from.
I think there is more to the physics of that. When you play two notes at the same time they'll make the air vibrate at their respective frequencies wich will overlap and interfere. If you graphicly add those two notes they'll produce a kinda weired looking mumbo jumbo, but if you pay close enaugh attention to the notes you'll see the difference in pitch. I'll link a picture real quick: imgur.com/a/6gVfP
Really cool!
Thanks!
I don't know if this is just me but the non existing note in the end of Mozart's melody sounded a bit detuned, it was recognicable as the fundamental but it was a bit off, Is my brain detuned? How can my brain pick up the detuning of my own brain?
Amazing. Would these be called sonic illusions or so-lusions? It's kind of a strech...
I'm just not hearing it at all. I turned up my volume, am using pretty high quality headphones and listened multiple times. I can't hear the tones at all.
Hmm... I'm not sure what else to recommend. Unfortunately, they can just be really tricky to pick out. I find the white noise example to be the easiest so that's where I'd focus on first. It might especially help if you did the one at the end, so you hear the "real" version of the melody first and then try to explicitly listen for that. Beyond that... I don't know, sorry!
Neither can I. I read about Tartini tones before and I knew what to look for... And still didn't hear it. I used decent headpones, played at comfortable volume, and nothing.
But I wouldn't say that it's bad. This effect bases on the way our brain processes information, so anything can happen depending on a person - from not hearing at all to hearing clearly.
So, our case proves the point - other people hear tones that aren't there :)
sihplak Here is a little tip for you: when you hear these weird noises try to sing the melody that you should hear in your head as if it's there. That will help your brain to find the melody in these weird noises. Sorry for bad english i hope it worked out for you.
For me, it sounded like the melody wasn't really coming from my speakers, but from "inside my ears". Try this if focusing on different parts of a soundstage helps you pick sounds out like it does for me.
That thing at the beginning is the first few notes of Eine Kleine Nachtmusik, if you didn't guess that
Yep! The first version I found used Ode to Joy, but I've always been a fan of the Nachtmusik.
I'm sending you the bill, to clean my brains off the ceiling.
^_^
Cool videos man, but watch out with those pitches volume, especially using headphones. Isolated frequencies above 1khz can be really harmful for your hearing, in fact many factory workers are exposed to machinery that resonates around a 1khz peak and being constantly exposed without protection will consequently develop an attenuation around that freq over time (sorry, not a native english speaker).
Yeah it HAS to be loud, but its very clearly there!
Yeah, that's part of the problem is in order to hear it you need some pretty loud, unpleasant noises, but I think it's worth it!
What happens, if I hear this two different tones separated stereo each in only one ear? It reminds me of binauralbeats, where I don't hear the "ghost tones" but my brain wave starts moving in this difference.
Oh wow! I just had to crank the volume and it's there.
Nice!
This is known as beating. You say the note isn't there, but it actually is. If you look at a scope, you can actually see the two notes form a beating freaquency; that is what you hear. In fact power chords on guitar are a prime example if a beating note, with the first and fifth creating a very pronounced note one octave below the root. FM synthesizers also exploit this principle to build complex sounds.
Okay, that's just freakish... At first, I couldn't hear anything but garbled, alien-like noises, kinda what I would expect to hear at a Karaoke club for R2 droids. Then I heard your explanation and tried again with better headphones, and I could actually faintly hear that Mozart-melody... It's vague, but it's there... Except it's not there... And yet it kinda is?
Hello!
This is very interesting, I didn't know about it.
However, you played loud unpleasant sounds that I had not enough time to anticipate with the pacing of the video which also sounded louder than the speech. That made watching this video pretty unpleasant for me and I think you may have needed to give that more consideration though I guess many people are less sensitive to such things.
Good luck!
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
Thanks for paying attention to my criticism and replying. Of course, apology accepted.
I appreciate you took volume into account but I think the unexpected timing was more significant. I watched another of your videos and I realize the fast pace is part of your regular format but I think that in this video it may have been a significant part of what created the unpleasant effect. Maybe it would have been better if you had a warning and a pause before each of these sounds.
Also, your videos seem pretty interesting, I subbed.
3:10 I almost had a heart attack and went deaf, geez dude...
This may be a bit silly but would you be able to make a video that analyses Party In The USA by Miley Cyrus?
I'll add it to the list!
*Gets barraged by noise *
AHHHHHHHHHH DAMN YOU SENSORY ISSUES AHHHHHHHHH IT HURTS.
i can't hear the 200 note when 1l and 1.2k are playing but i can hear it with the other combinations
Interesting! That's much stronger for me than the 1.1 and 1.3k one. Not sure why that'd happen, but the human brain is really complicated...
Nonlinear distortion is the name. :D
where can we get hertz tone waves?
The audio for this video was generated with SuperCollider, which you can find here: supercollider.github.io/
Thanks so much! Downloading, time to learn code.
So, this is the concept behind beat frequencies, yeah?
I am using headphones and I know that these effects are real. But sadly I wasn't able to hear any of the sum tones. Or most of the difference tones.
I did make my own overtone series though and I usually couldn't hear the difference tones without at least 3 sine waves. At least at the distances from the fundamental similar to those in the video. Maybe my hearing is just bad.
Edit: On a second watch through at higher quality, I was able to hear the 900Hz sum tone.
Yeah, the sum tones are really, really hard to pick out. I had to try it four or five times, relistening to the 900 first every time, before I could convince myself I was actually hearing it.
It's actually not really in your head, if you have two sine waves added together, they can be written as the sum of the two frequencies as an overtone of the difference!
You can really hear these when in a small practice room playing a vibraphone lol
needed a warning before that sliding pitch awfulness at 3:08
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
12tone no need to apologize!! love your vids, this one included. super interesting and great presentation keep it up!!
i like it... what not means I understand full out
In your version of Eine Kleine Nachtmusik, I could only hear the last two notes. Additionally, I couldn't hear the 40 hertz tone. Am I too young (16)?
I suspect it has to do with your headphones. I found out after putting this out that some portion of the tone is actually manifested in the signal due to distortion, so if your headphones don't have a strong low end it's possible that you're losing that part of it, making it harder to hear.
I absolutely love your channel, everything about it, your theory, communication style, everything
...but your explanation of the base Tartini Tone here is outdated by about 40 years.
Dr. David Kemp proved in 1978 that "otoacoustic emissions", intermodulation distortions, actually occur on the basilar membrane. For decades now, the field of medicine has sent two tones, just like in your example, into the ears of infants with two isolated speakers and a microphone on a same probe to detect the "echo," in order to capture and analyze one of the higher distortions (than the tone you describe here.... Two isolated speakers are used to help insure the distortion doesn't occur before the sound leaves the device because that, too, can be problematic. Your "signal chain" in your computer software might tell you one thing is happening, but by the time the entire signal makes its way through all the circuitry to the final computer output...a distortion may still occur electronically. Two isolated speakers, one for each tone entering a single ear, help insure that is not occurring....because intermodulation distortions are a phenomenon that doesn't just occur with acoustics. It occurs with radio waves and electronics as well, and the basic math is the same.)
But researchers and physicians still see the distortion tone you're describing (f2-f1) all the time as well, in the ears of humans and dozens of other species. Otoacoustic emissions is a deeply researched subject since Dr. Kemp...and combination tones are part of that.
Point is that f2-f1 isn't being "created by the brain." It's an actual vibratory distortion on the basilar membrane itself. In 2020 researchers in Oregon even saw the 4f1-3f2 distortion on the reticular lamina (parallel to the basilar membrane). In other words, they're finding more difference tones now than they were 40 years ago with refined methods.
The Music Pedagogy world seems to be catching up slowly.
All that said, your channel here ROCKS. I learn new things from you all the time when I pass by this channel, and I really appreciate you putting it up.
ow
Apparently I'm terrible at perceiving sounds that I'm not hearing.
This was a super annoying video to watch when the rest of the family has already gone to bed.
I've had tinnitus for almost all my life and I hear combination tones almost too easily.
That's too bad, tinnitus is never fun. It's nice that it works for you here, but still, unfortunate that you have to deal with it.
Whoang..
Were we supposed to hear something when you played 40Hz at 0:49? 'Cause I heard nothing.
Hmm. It's possible that your headphones don't have a enough bass to play that note audibly, maybe try a different speaker if you have access to one?
had to turn it up alot
Yeah, they're pretty faint. I didn't want to make it too loud, though, to avoid blowing out people's ears unexpectedly. Glad you could get it to work, though!
12tone is left handed
0:54 sounds like 8kHz to me
Huh, weird! I programmed it with a sine wave generator so I'm fairly confident that it was 4k. Not sure why that's happen...
What software did you use? I want to run some experiments. Any software that can receive an input of hertz, and output a soundwave with those values, will work. Preferably with a timbre, but sine waves work too.
Cool.
Thanks!
WATCH YOUR GODDAMN VOLUME
Tinnitus in one ear is more than enough for me already.
Sorry! I tried to keep them reasonably close to my voice's volume and I played them for my brother to make sure, but they do have to be somewhat loud otherwise the effect is lost. I apologize if I messed up that balance.
Blown = Mind
^_^
I didn't hear anything
I hate you
just kidding
but in the sliding tone part I missed the volume down button and turned the volume up... and it hurts
Sorry! I tried to set the volume around where my voice was, but I kinda screwed up the balance on that sliding tone...
Holy shit! 8-o
Those two chordswrr 8 days a week