I vote for this video to be the best you have made in 2024! Thank you for sharing! Incredibly interesting and thought provoking. Thank you! I will read the article as well :)
Nice video! This also explains why different types of noise, like RFI, EMI, and ground-borne vibrations, change the sound, even though you can't consciously hear them through the speakers. I have spent the past two decades dedicated to controlling system vibrations, as I found that shielding techniques did not provide good sound quality. In the past, I used 100 sheets of Stillpoints ERS Paper and built a shielding cage around my system, but I no longer use them because they made the sound too dry and dull. In fact, some cables sound better without any shielding, resulting in a more open sound.
Not many in the hifi community recognising the importance of psychoacoustics in music recording and reproduction. Similar empirical investigations have successfully explained our aesthetic response to analogue AAA recordings over digital. As humans our measurement tools are way off (as you referred to) in explaining in particular our emotional and feelingful responses to music as well as other art forms. You’re ahead of the curve Lachlan. Thanks again
Super tweeters are a bad idea. Sure they'll give you higher frequency response above 20khz, but they'll give you serious combing issues in the crossover region with your normal tweeter unless you place them with a C-C distance of just millimeter, which isn't even physically possible to do.
a couple years ago when I had COVID and had to go to the hospital due to chest pain, when they were doing an ultrasound on me and when it specifcally touched/vibrated my bones I could hear it plain as day. I asked them what frequency their machine operated and they asked why, "well because I can hear it"
Yep. I get that with the ultrasonic tool used by dentists to clean teeth. It MIGHT be a lower harmonic or sympathetic resonance we hear or maybe it's something else - I'm not sure.
most likely an excitation of subharmonics. Also some of the supertweeters in highend offer not much more than their own subharmonics which are excited (by bad drivers) alongside frequency content in input signal.
If they didn't tell participants which versions of the music they were hearing (which they didn't and they randomised the orders they played the samples) then placebo isn't in effect.
Would've loved to see you present some of the research that presents evidence to the contrary. Just because one paper says something, doesn't mean it's necessarily true! With a controversial paper like the one you cite, it's definitely good to present both sides, I feel
Agreed ... one sided science is simply a sales pitch. But I would put more value in studies and research to find out how much this impacts the enjoyment of music. Also ... Who funded this research??
There's nothing controversial about this topic and there are many studies cited within that discuss similar measured phenomena. I'll be exploring them further so we'll see what we find as we continue the journey through the various studies on the topic.
@@PassionforSound Are we influenced by tympanic (acoustic) vibrations above 20khz ... *YES* ... we are. Are we influenced by tympanic vibrations below 20hz ... *YES* we are. There's no question of that and these surveys you rely upon are not new knowledge. They were actively experimenting with infrasonic weapons in World War II and, more recently ultrasonic weapons were used in Cuba to cause illness in the US Embassy there. None of this is new science. But before we go getting all excited and begging for ultrasonic content in recordings, we really do need to ask a few simple questions ... The first of these is whether it will actually improve the reproduction of recorded music in any meaningful way. Then there's that sticky bit about bandwidth allocations... and then we have to ask how much it will cost to rebuild every recording studio on the planet to accommodate this new phenomenon. Do you have any clue how much a recording console costs? Then there's the new gear we would all have to purchase... it won't be cheap either. And all of this over what? -50db harmonics from a musical spectrum that technically ends at 4,200hz? Really .... you guys all need to give this a _whole lot more thought._
I have argued for years that we can hear the sound or the effect of sound above 20Khz, try this simple experiment ; play and listen to a 10khz sine wave, 10khz square wave and a 10khz triangle wave, they all sound different ? The only way that they can sound different is because you are hearing the harmonics i.e 20Khz, 30kz etc. Anyone that has tried a good supertweeter will also attest to the airiness and 3 dimensionality that you get when you switch it on , easy to blind test by someone switching on and off.
"super tweeters" fed from a regular audio system, playing "ordinary" recordings, will just be increasing the audible high frequencies. Nothing "wrong" with that, if you like a lot of treble, but if your system already had a flat response, you've now "unflattened" it. Of course you can hear the difference between having it switched on or off...same as if you disconnected your "regular" tweeters! Unless you're pre-filtering a "super tweeter" to not cover the same frequencies as your regular tweeters, it's just additional hf "reinforcement".
That's possibly the case, but it's also possible that if the source chain and recording are reproducing sounds above 20kHz AND if the person is old enough to have the expected high frequency hearing loss attenuating sounds above 15kHz then the difference COULD also be due to ultrasonic content. It would require a controlled test with a deliberately tuned crossover (as per the study in this video) to test that effectively.
This is fantastic, and I'm not surprised our brains can tell when ultrasonic frequencies are present, but having a well done study confirm this is appreciated.
@@Douglas_Blake_579 Can't do peer review on your own? The peer review process is also corrupted and broken in academia, so good luck waiting on the indefinite feedback.
Interesting video. I have been saying, on my RU-vid channel that a wide bandwidth, extending up to 100Khz+ and a very fast slew rate is very important in HiFI preamps and amplifiers, which seem to add more detail to the sound compared with the normal 20Khz of most audio products. These test results would largely confirm my reasoning for wide bandwidth. I thought I was alone with such a hypothesize. I will recommend your video to my viewers, saves me trying to explain lol
Thanks Michael. I've found similar subjective experiences too. I have a feeling that the slew rate is important for timing accuracy. The frequency extension is curious because most music won't be captured with all that high frequency information and yet many of the devices with broader range seem to sound better. I'm still pondering how that works...
We not to hear ultrasonic as what we perceive as sound but we can perceive it as presence, I found this out last week testing tweeters and even at 22KHz I could detect it with my ears and I'm 61.
I am listening to an Audible book right now by Dr. Daniel J. Levitin. He wrote the book "This is your brain on music" and his newest is "I heard there was a secret chord". He is a Neuroscientist and a Musician. Very interesting work. His book was just released in the last month or so. I have tinnitus and hearing loss and I am grateful I can still enjoy and play music in spite of it all! God bless.
I think this subject is super & the one you have made since. I first started watching you several months back concerning the hifi products you reviewed & they are good. This is so much more informative & shows ways to improve & learn on how to hear & listen. I surely want to see more videos about this! Thanks!
Interesting video. I know I have reduced hearing, but if I go too close to an ultrasonic pest repeller that rotates through 3 frequencies, I can 'feel' if 1 frequency in particular is on. I, therefore, usually set it to rotate through 2 if I am in the house. In my case at least, I don't need to hear the 65,000 Hz for it to have an effect.
I used to be able to hear them consciously when I was younger. I've lost some frequency bands in the meantime, but not contiguous bands - so eg my 6k band is impaired, but those above it are minimally affected. I currently have a bluetooth dongle that, when it not connected to anything, "pings", looking for something to connect to, and I can hear that. It was driving me a bit crazy as I had no idea what this regular, barely audible but annoying "peep" was. Then I noticed it coincided with the light on the dongle blinking on, then off when the peep was over. Unplugged it and the peep was gone. Crazy that something barely audible would capture my brain's interest that much, to the point I *had* to figure it out :D
I went to japan and had the top of the range berrilluim coklear tad ear implants.some specs include a 4hz to 160khz bandwith with a 140db dynamic range all at below 0.1 distortion so i agree with your assessment. I love them.
Did you have a different alternative before? I'd be interested in the differences you heard if you went from a smaller bandwidth version to a higher bandwidth version.
For those inclined to treat this as some grand revelation that is going to change music forever ... Stop and think about the time you spent listening to FM Stereo broadcasts. FM stereo uses different information on the upper and lower sidebands of the transmitted signal and carries a 19khz pilot tone to activate the stereo discriminator. How many of you actually heard those pilot signals? (I didn't) If they can "sneak" that one in on you... how much do you think low level harmonics above 20khz is going to affect your listening experience?
Thanks for this fascinating post. This is not entirely new. Decades ago, I purchased the Pyramid speaker system engineered by Dick Sequerra. This was a modular system with compact midbass/tweeter units that could be used by themselves, subwoofers, and the final upgrade, ribbon tweeter units. The ribbon tweeters reached into the ultrasonic region and were marketed by the claim they reproduced inaudible "formants," which nonetheless aided the brain in perception of spatial information. Now, it seems like the science has validated the marketing. It's not all snake oil.
I agree. There have been those who've understood this for quite a while and some of the studies reach back a fair way too so the science has been there as well - just not widely discussed.
I've always known that I can hear much higher than I used to think. Try this experiment. Get tone generator to produce a high frequency a bit higher than you think you can normally hear. Now modulate the volume up and down. All the sudden you'll be able to hear it if it's not too high.
There were some experiments cited in the main paper I discussed in this video where the modulation of inaudible frequencies was perceptible (not necessarily audible) while a fixed tone was not. It's interesting.
@@dangerzone007 While you're at it... study up on "Beat Frequencies" and "Intermodulation" ... both of which clearly explain your pehenomenon. For example: If you mix 30khz with 31khz you will also get both their sum (61khz) and their difference (1khz) as sidetones. The 1khz sidetone would be clearly audible. Yes, you can manufacture those effects ... but do they actually happen in music?
I imagine that any time you have multiple frequencies played concurrently (i.e. music) there'll be all kinds of interactions between the frequencies and our brain's perceptual processes.
Reading through many of the replies here, I find a lot of people making one rather simple mistake ... unless those "super high" frequencies are burned into the recorded material (which is extremely unlikely) there's simply nothing to hear. So messing about with filters and EQ is really just messing with silence and inviting more noise into the playback.
@@PassionforSound At what cost? Seriously .... this tempest in a teacup thing audiophiles do is getting pretty ridiculous. Not so long ago it was all about Post Filter FeedBack in class D amplifiers. Until people realized it was all about 1db of variation at frequencies that are virtually silent and very few people could hear, there was a loud outcry for it. Every reviewer, lots of audiophiles, all screeching that Class D is no good because it is load dependent... prices going up, equipment becoming more complex... and all of it over something literally nobody was going to hear. This is no different. Now that it's been announced, there will be a clamour for it that will continue until people finally realize that whatever difference it might make is so trivial as to not warrant even pennies of extra expense. It will be _literally_ not worth the headaches. You don't seriously think that pumping a room full of 30khz snaps and crackles that nobody can hear is going to make music any better... do you?
Also the playback equipment likely outputs only the standard 20~20 kHz range. This is why I think 24-bit is more important to us regular music listeners than just higher sample rates as the higher bits affects dynamic range - something we've been able to tell since the transition from vinyl to CD.
@@IvyANguyen Dynamic range is a whole other issue. The only reason that CDs appear to have low dynamic range has nothing to do with their capabilities ... it's the idiotic mixing and mastering used on CDs as part of the "Loudness War" (do a search). In terms of actual dynamic capabilities, CDs are capable of wiping the floor with even the very best Vinyl. We're talking 95db vs less than 40.
@@IvyANguyen Actually most playback equipment goes well beyond the 20-20k range. I've got mid-priced amplifiers here that easily handle 5hz to over 30khz. But that's done to ensure the 20-20k is covered properly with a flat frequency response. The limitation has always been the source recordings. They seldom get to the full 20 to 20k range.
Perhaps that's the reason people didn't like Yggdrassil More is Less but liked More is Better despite the distortion improvements being outside of audible range
I have no doubt that vibrations below 20hz and above 20khz do affect us in some ways. But... We also need to be aware that the "20 to 20khz" everyone always talks about has next to nothing to do with human hearing. It is, in fact, a Bandwidth Allocation in the EM spectrum, just like FM Radio (88 to 108mhz) or Cell Phones (700 to 900mhz). These allocations exist to prevent important services from interfering with each other and to provide protected space needed for certain functions. (Radar, for example.) It was arrived at by looking at the "bandwidth" of music. The lowest note on a standard piano keyboard is at 23hz, the highest is at 4,200hz ... _yes that's right_ ... four thousand two hundred hz. But it was also noted that these musical notes produced both overtones and sidetones that could reach much higher and to remove or limit them would impact the quality of reproduced music. So it was decided to preserve the first 3 harmonics of the highest note... 8,400hz, 12,600hz and 16,800hz, in order to preserve the musical timbre of various instruments. Add in some guard space to minimize interference both with and from other services on the spectrum and you end up with 20hz to 20khz. Thus; the eventual decision to reserve both Electromagnetic and Percussive bandwidth from 20hz to 20khz for "quality musical reproduction". Since this is a reserved EM bandwidth, no radio transmitter or other sources of radiated EM emissions can operate between 20hz and 20khz... preventing mass interference with audio equipment. Any consideration of what humans can actually hear was secondary to that decision. So, when you listen to music, what are you actually listening to? Well, Middle A, used for tuning, on a piano keyboard is 440hz. The fifth harmonic of Middle A is at a measly 2,200hz. Those ultra trashy cymbals in your favorite orchestra are probably at about 800 to 1,000hz, the ride cymbals in a typical drum kit are at about 600 to 800hz. Even the tinkly little triangles seldom get over about 3khz. Above that 4,200hz demarcation it is all harmonics decreasing exponentially in amplitude as their pitch increases. Above about 10khz there is almost nothing to hear. While extended hearing is an interesting discovery, I seriously doubt it will change the way we experience the world or how our beloved stereos work. And before you call "BS"... do your homework. I can't post links here but you can do a few searches and find all this and more... and it's a very interesting read.
This all makes FAR too much sense for an audiophile to believe! 😄 As a professional in audio/video engineering, however, I enjoyed your post. I'd actually never realized quite how "low" the fundamental frequency of a piano's highest note is! While this ultrasonic-frequency research is "interesting", as a "curiosity", unfortunately it just fuels the audiophile "high res" fire. Now we'll have audiophiles demanding that everything must have a flat response all the way up to 100KHz, or else it's not audiophile-enough for them. That should keep them "happy" though...another thing for them to obsess about, in their never-ending quest for perfection 😄 While I certainly don't miss the "old school" audiophile issues such as wow & flutter, at least those were real, audible problems, and higher-end gear had audibly higher quality. These days it's like audiophiles have run out of actual problems to worry about, so they just invent new ones 😄 Thank God there isn't a modern-day video equivalent to "the audiophile". Well, there would be, I suppose, were it not SO much easier to disprove their BS. With a visual medium, there's literally no room for subjective opinions of quality. Poetic nonsense about "inky blacks, sparkling highlights and dazzling rainbows of colour" would quickly be proven, or disproven, with basic test gear or anyone with normal colour vision. "Opinions" would be irrelevant. The "invisible" nature of audio leads it to be wide open to subjective opinions. At least for audiophiles. Engineers tend to trust our measurement devices 😉 Some companies have TRIED to do the "audiophile" thing, with $1000 HDMI cables and the like, but it really is so much easier for anyone to call BS on that. *EVERYONE* can literally see with their own eyes that these things make no difference 😄
@@njm1971nyc On the home theatre side of this, they're calling themselves "Videophiles" and, yes, they're buying $1,000 HDMI cables and $150 per foot speaker wire. Some people just never learn. I would strongly advise any "audiophile" to grab one of the free "signal generator" downloads and spend a bit of time learning to recognize various frequencies. It's a rather rude awakening to realize just how shrill 1khz is or how far beyond music 10khz is. Once familiar with the actual pitch of sounds it will change their entire perception of music and, yes, even movie sound. The look on people's faces the first time they realize the drummer's high-hat is actually lower pitched than the solo guitar rif is pretty entertaining. Of course the same is true on the other end. Infrasonics is a truly fascinating study. For example... finding out what 60hz sounds like usually brings wide eyed surprise. Then comes the realization that most of what they consider to be "deep bass" is actually above 100hz. Understanding the lowest note on a double bass viola or bass guitar (41hz) is a full octave (twice the frequency) above the lowest piano note changes your whole perception of music. I'm not blessed with perfect pitch... not by a long shot. But over the years of running test tones through stuff, learning to recognize their sounds, my expectations of what a good stereo system has to do have changed rather pronouncedly. Certainly, discovering the top octave (10khz to 20khz) of the audio bandwidth is largely silent when playing music was a real big eye opener... Finally for those dealing with age-related hearing loss in the top octave of the band ... Don't worry. As long as you can still hear 8khz, you're hearing the whole song.
This is all interesting information, but I think it's also important to understand that all decisions made in areas such as the sampling rates for digital audio (i.e. 44.1kHz), and probably much of what has been decided for video reproduction too, is decided with the knowledge available at the time. Whole industries evolve by integrating and leveraging new information and studies. Some brands are already leveraging the type of understanding discussed in this video so it will probably take some time and may never be completely mainstream, but I suspect it will continue to influence the designs of products from those companies truly seeking excellence and innovation.
@@PassionforSound Except for one small problem you appear to have overlooked ... "Audio" is a bandwidth allocation, agreed by treaty with multiple countries. There are vital services such as medical, scientific and security systems using the EM and Tympanic bands directly above 20khz that cannot be moved. If you expect to just "take up more bandwidth" with "high definition" audio, you are sadly mistaken. The minute audio gear starts interfering with sonograms, echolocation or tripping bank alarms, the hammer will come down pretty hard. In Canada this is overseen by Industry Canada, in the USA it's the Federal Communications Commission... Not sure what the agency names are in other countries... but any country issuing callsigns to radio services will be a party to the treaties. Sure we are influenced by more than 20 to 20khz ... no argument. But it is very unlikely that any such information will be coded into recordings any time soon. Moreover, it's influence would be so minor that it would not make any sense to do so in light of the technical difficulties it raises.
@Douglas_Blake_579 I would understand that for the wide transmission of audio, but ultrasonic sounds already exist in the world and don't cause those problems. Having them included in the playback of personal audio would be no different than someone playing the actual instruments live with their full sonic range. I think you're overthinking it.
They came out of the woodwork for this one brother. Well done. In other news I the audiologist I saw recently dismissed my concerns about my tendency to listen very loudly to my OG Kennerton Valis and Yamaha YH E600s. Dismissed selective hearing too, or at least condemned us all to it. He was funnier than me and I was trying. Anyway spent some time in the time machine and was shocked to discover my hearing is normal for my age. Seems the guys on Head Fi were wrong. I suspect the Audiologist would laugh at your video. Nevertheless I love your work.
This backs up what I’ve thought for a long time. The brain, like many things in nature is way beyond human invention. One thing I’ve noticed since buying the HE1000SE, which many say is “to bright” is that some music sounds awesome, and some music that sounds great on my cheaper headphones sounds pretty terrible. So I had a play around with oratory’s EQ settings for this head phone. A lot of modern pop is digitally recorded quite compressed. This sounds great on head phones like the Arya stealth, HD 600 etc, but the HEKSE pulls it apart and you can hear a lot of faults. When you EQ to oratory/ crinacle etc, the biggest change to match Harmon curves etc is reducing 16khz by 9-11 db.. suddenly the modern pop (swift, dua lipa etc etc) sounds a lot easier to listen to…by reducing a frequency that at 52 I can’t hear .. however, when listening to live recordings, orchestral music, a lot of jazz and well recorded rock (for example Stevie Ray Vaughan, dire straits) the opposite applies. The Harmon auto eq settings just take the life out of the music. Switching off the eq somehow opens the sound stage, and the ambience of the music.
EQ alters frequencies by shifting the timing of the signal to create constructive and destructive interference. Unfortunately, in most cases this smears the timing of the signal and damages some of the tiny, largely imperceptible cues that our brain needs to make proper sense of the sound. That's why everything can sound more "right" once the EQ is off, even if the tonal balance isn't as enjoyable.
I learned in electronics class when I was studying to be an electrician, that humans on AVERAGE can hear 20-20KHz, but that when you`re young you have a broader spectrum, and some people can also hear higher/lower as they age. We played around with frequency generator, speakers and oscilloscopes to see exactly what frequencies we could personally hear, which was very interesting and fun (: IIRC my range at the time was about 18Hz to 24KHz, and I still have sensitive hearing as well, to quote the audiologist in the service after my sideman had a premature discharge at the range, followed by a reflex shot from me (oops): "your hearing is severely accute and extremely robust". This was after having tinnitus for about 90 minutes prior to being ordered to see the doctor. Needless to say I recovered quickly and still scored VERY high on the test, and I can`t say I`ve noticed a degradation the last 2 decades (: TL;DR: the 20-20KHz thing is an average, not an absolute ;)
The 20 to 20khz is not even about the capabilities of the human ear. It is a band reservation in the EM and Tympanic spectrums that is derived from the frequency ranges of music and other sounds. It does not matter if we hear more or less than that... that is the space reserved for audio.
@PassionforSound : You should have selected as intro the music from the 1975 movie Jaws .. just smiling and adding some humour to the brain. Kidding aside: I have a training in biochemistry and pharmacology, and you have a very good talent to explaining basic research science into spoken word. My gut feel tells me, that the study is spot on and on the right track. Thank you for sharing here.
Thank you. I'm glad you liked the video. I think my formal education helps me to understand what's going on when it comes to research and hearing so I can (hopefully) make it clear for anyone to understand. 🙂
Fascinating stuff. I wish recordings were done in 32-bit float and included a much higher frequency range. Then the user could dial in some filters to their liking. Much like how a camera can shoot in some kind of Log format to capture very high dynamic range and then edit and filter it in post to make it look good.
Yep. AFAIK, the bit-depth isn't the issue as that's about dynamic range. What we need are high sample rates for the capture and playback of music plus the gear that can receive (microphones) and reproduce (amps, speakers, etc.) those frequencies
Listen to a recent Darko podcast that also talks about the importance of high frequencies and how they affect the phase relationship of the high frequencies you can “hear”.
It kind of matches some people's experience with high-quality up sampling on 44.1 recordings using hqplayer or Rob Watt's upscaler - me included (and I thought it was all BS, until I tried it... although it becomes less obvious with high-res recordings). However, I am guessing it probably has something to do with time domain information instead of frequency information - this is somewhat supported by their finding that "none of the subjects recognized the HFC as sound when it was presented alone" and "no enhancement of alpha-EEG was evident when either an HFC or an LFC was presented separately". Love this kind of video! I wish there were more this kind of content around psychoacoustics. It would be great to have a discussion around this with other reviewers, maybe from theheadphoneshow, and manufactures such as Schiit, Geshelli, Chord, and even Benchmark and Topping, for diverse opinions on this topic!
I'm glad you liked the video! I'll be sharing more content like this in the future. As for the upsampling question, that's definitely timing-based and not at all frequency based because there's no way to create frequency information that wasn't captured in the original recording. I agree though that the timing stuff does make a significant difference too.
I recently listened to a descending frequency test starting at high khz extending to low end. I pick up audible sound at about 16khz. Later i used EQ to kill these higher frequencies and found i could definitely hear the difference. So, there's an easy way to test for yourself. More grear content from one of the best!
That's an interesting test. Thanks Peyton. Actually, as I think about it, introducing EQ will immediately alter the sound due to phase shifts which will (I think) also affect harmonics so it might have been more a test of EQ's subtle influences than just isolating high frequencies.
@@PassionforSound true. I was a little surprised and a little relieved. I'd be very interested in knowing more about EQ's effect on the signal chain. How about a sequel?Maybe episode on DSP?
@@PassionforSound Shorty after noticing I could perceive something, i did room correction using Wimi Pro. I was amazed how much the sound was "improved," but was left wondering about what that really meant. Not sure i can call myself a signal chain purist. Maybe trying to avoid that level of commitment....
@peytonsnead3114 I'll see what I can find for a follow-up. I am similar to you where I'm often on the fence about signal purity. With headphones, I never use EQ, but with speakers, it all depends on the circumstances and whether I'm critically listening (no EQ) or enjoyment listening.
So the room correction. It really tamed the bass, which I've read is difficult to achieve with room treatment. The adjustment is based on Harmon and was definitely more pleasing to the ear.
this is so cool, and I have to say I'm not quite surprised that we can "sense" these things without having a conscious experience. I mean, we are still animals after all, and in terms of evolution we are not so far away from our primitive origins where heightened sensory perception would be important for survival if nothing else. From my own experience, not too long ago I wanted to reality check what different frequencies sound like - just to put the number on the tone - and at some point I got down to 30 hz. I couldn't really hear it, but my head felt like it was vibrating, and I started to feel nauseous in no time - and this was at very moderate volume with speakers that are only rated down to 40 hz. Obviously it's not normal to hear a constant tone like that, there was probably some distortion generated, and I think this is at least partly to blame for feeling icky as a result, but it stuck with me - this physical response to something I could not have identified if I wasn't clued in to the experiment. It also makes me wonder about the claims that eg NOS dacs "sound more natural" because they are not guesstimating values during oversampling, and that the brain is more disturbed by incongruous information than by missing info (which it will interpolate itself, if necessary, to something that naturally fits). And I'm also thinking of the PFFB implementations that push load dependency spikes out to the 30k+ range "so you never hear it" (or do you?) I have no idea, but all of this if very fun to geek out over - special thanks for this one!
That's really interesting about the PFFB influence because I just found myself preferring the sound of the ZA3 amps (no PFFB) over the otherwise identical V3 Mono amps because it seemed somehow more natural...
Very interesting video, well presented and edited. One small note, please get rid of the popping sounds, very irritating, with or without the high frequency content. 😉
It would be so fascinating to get Rob Watts take on this, given his thoughts on how so much of the timbre reconstruction and spatial and timing awareness comes not, if I remember, from an appreciation of high frequencies beyond our supposed hearing range but many decibels below what we can hear. But the principles would seem to be the same - the ears as an instrument supply X - but the brain extrapolates X squared plus possibly Y and Z from all the other things we capture with our bodies possible not even with our ears. This opens up a whole new avenue of research and in some respects is confirmation of what that likes of Rob Watts have been telling us for years and designing for - well beyond that narrow band of hearing because the brain is more sophisticated than just what we have discovered its users as one of its sources of creating an auditory landscape
Absolutely! I've chatted to Rob about this offline and it's all a part of what he considers when designing DACs. I wonder, however, how the digital filtering needed to remove aliasing noise might alter the ultrasonics of the actual music. That's a topic we haven't covered.
Very interesting. It sounds like its opened up a lot more questions where experimentation would be interesting. For example it would be really interesting to take the necessary highend recording equipment to different natural locations such as a rain forest and I wonder about the outback deserts or caves with river flowing through them and see if these sounds above 20kHz exist and either way, play this soundscape back to people in a specially designed room with the participants surounded by acoustically transparent projector screens (so as to hide the audio equipment and project high resolution video of the scenes where the recordings took place and measure their brain activity and what they themselves perceive within the audio, video soundscape. I know you could take the groups to the locations but apart from the expense, you would introduce tiredness and potential irritation within the group on the way to the destination, skewing their mood and thought process. You want people fresh and relaxed as possible for such an experiment. That can only really be done in a controlled environment.
Very interesting video this. I used to be able to hear well above 20 kHz, with my actual ears. I could hear high frequencies from the high Voltage transformers in the old Cathode Ray tube TVs which from what I remember was about 27 kHz. I also heard those plug in ultrasonic bug repellers. I've always thought that this was my reason for getting into high end audio in the first place because on crappy audio the high frequencies seem to be most prevalent and distorted. Now after seeing this video, I'm going to have to re-think all this. Of course, those freaky ear days are now well and truely behind me, but I would still like to do an experiment to see how high I can still hear. For reference, an ordinary audiologist I believe only measures up to 8 kHz.
@@njm1971nyc I'm Dutch so we were using PAL. No idea if I'm right about the 27k though. It's just a vague memory. What I do know for sure tough is that many people couldn't hear them and I did easily.
Our brain is more than a DAC 😝 interesting. Really nice video. Ps i did a quick uncontrolled experiment with my son who is 7 years old. He was able to hear the frequency around 2k ( if he was actually hearing it) while I could only hear it around 14k. Another video it was mentioned that our ear drum has finite no of hours dedicated and the more we use them the number goes down. Your video changes everything 😇
It blows me away when people say that burn-in isn't real and headphone cables make no difference. It's obvious to me that they just haven't learned how to measure it. People get very emotional when you tell them there's a difference in sound. A lot of times, they'll insinuate that you're delusional for suggesting the differences.
fact on fact...for me, to detect it, its a kind of minuscule tone shift and pitch which I can detect--which most people, for some reason, cant. It like how a person can have or detect 'perfect pitch', which is a skill most people dont have...same with this with audiophiles hearing about 20hz and differences of sound in cables, bitrates,etc.
Yep. I believe it all comes down to the fear of uncertainty (which we all have to varying degrees). Proposing that something is possible despite lacking or even seemingly contradictory evidence (e.g. no shift in measured frequency response) can really push people's fear buttons and that leads to some strong reactions.
"burn in" of certain components has some validity, such as speaker driver units, but burn-in of cables is just voodoo nonsense. Complete and utter nonsense. People also believe in "God" and the power of prayers though, so...go figure! People will believe literally ANYTHING if they trust the person they're hearing it from. Unless you're able to identify a "burned in" cable, from a "non burned in cable", audibly, and prove it, then I'd suggest not believing all the rubbish that audiophiles are telling you. It would be a super-human skill almost on a par with mind-reading to be able to distinguish between burned-in and "virgin" audio cables. I'm not wealthy, but $10k says you'd fail if I tested your ability (and I'm good for the $10k!). Hell, if you really could tell the difference, under test conditions, it would end up being the most viral audiophile video on RU-vid, and I'd quickly recoup the $10k 😄 up for the challenge?!
This is why I hate the idea of ringing in digital filters, it might not be audible as some say but I think it has an effect on listening fatigue. Ringing is not natural in the real work so I believe it should be reduced as much as possible. Just a thought that I think could relate to this video.
Ringing is totally natural and ordinary. How do you think bells, triangles and cymbals work? Basic principle of resonance: Any object, when struck, will vibrate at it's natural frequency. Everything rings.
@@Douglas_Blake_579But how many things in the natural world pre-ring, before they’re struck, is his point I think, at least in part. The amount of a digital filter’s pre-ringing ahead of the transient edge depends on the filter selected (linear vs minimum phase etc), as will the extent and amplitude of the post ringing.
@@Douglas_Blake_579 Agree re the natural world (that was a rhetorical qn), but a quick google will bring up some plots of standard digital filters, showing pre-ringing ahead of the recorded ‘transient/excitation’ is a real thing with linear phase filters, it can be avoided with minimum phase filters but at some cost of introducing phase anomalies at different frequencies.
Ringing in digital filters doesn't equate to the analog sound that's reproduced AFAIK. Rob Watts discussed this in an interview with me a few years ago and explained how the pre and post ringing is actually important for the mathematical processes used to calculate the correct output signal
Great video. For me it confirms what we all "seem to know already"... we are perceiving frequencies, that we cannot hear, in some way to reconstruct spacial information. Especially for soundstage depth the high frequencies are key and how they are reproduced by the audio gear. If this is "correct" then the space between instruments is credible and the soundstage has real dimension instead of just being airy. Much of those high frequencies of reflections have a very low volume and therefore your noise floor must be really low to take advantage of them. This is my experience with the audio gear I use.
Oh my goodness obviously I was referring to a high end system playing hi res, you would assume that from the comment , you can measure it and you can hear it. If you havn't heard it for yourself then have not heard a high end system
Such a great video: I convinced myself that I couldn't hear anything over 16,000 even though I could hear more. I will try it again with no non-scientific methods and equipment.
It's likely you can't consciously perceive sounds above 16kHz. What this study showed is that there are other mechanisms affecting our perception of audio beyond the "conscious hearing"
@@hugoanderkivi That would be interesting, maybe the sensitivity isn't to the treble itself but to the abrupt cut-off at 20-22khz with modern playback equipment? Equipment with a treble roll-off would smooth out that abrupt drop when frequencies hit the bandwidth limit of digital.
@ResilientME This makes sense. I feel the Topping DACs seem to do that, especially. The Chord Mojo 2 sounds significantly more open and natural as compared to my E50, and I imagine some of the difference is just that cut-off in the high frequencies and possibly above.
@@shipsahoy1793 Yes, and some people wear glasses and some people wear hearing aids. There are tons of variables for any subject. There is a frequency range that whoever made it up says humans can't hear above or below it is it a fact? 🤔
🤔I have a highly resolving system but I am old and I can't hear a 15 KHz hertz oscillator like I could when I was younger. Through DAC filtering experiments, I found that if I filter out the higher frequency content on the DAC above 18 KHZ, as opposed to allowing the full range attenuating above 24 KHz, I sense warmer more relaxing sound, even though I barely hear a difference. The music sounds slightly brighter, but I prefer the truncated bandwidth, which seems more pleasant. I've tried to disprove this with many different headphones, as I felt the room speakers have yet more variables, but I can't come to any real conclusions bc of the potential bias of a priori knowledge of the comparison. i've gone over this many many times on many different occasions with many different pieces of source material and the result is either always the same or barely perceptible so I don't know I guess everybody draws their own conclusions based on their experience, but I can't even rule out potential bias from within my own flawed "human" brain.😉
The filtering bandwidth can affect time domain behavior all else remaining equal. Phase shift, as limiting bandwidth tends to introduce, can make sound warmer/relaxing in my experience as it ever so slightly delays transients in the higher frequencies. I think this is why certain brands prefer minimum phase filters for their DACs.. full range bandwidth + subtle phase shift.
There's also the influence of noise in the ultrasonics and the influence of those. The aliasing noise in DACs is all pushed into ultrasonics and that's why we have the various filters to cut them out again. This poses some interesting questions though when we start talking about needing to reproduce ultrasonic musical content.
I have a really really fascinating experiment for you to try. Get yourself a ultrasonic dog training device. The type that has a bunch of ultrasonic transducers on the front and blast ultrasonic sound when you press the button. Just a cheap one from aliexpress is fine, as long as its got at least 2 transducers. 3 is better. Place it at the location at the base of the scull, where it meets the spine and press the ultrasound button. You might need to move it around a bit, but for some people there is a location where they suddenly hear the sound in this location. As in, you detect sound at the base of the spine. My personal, extremely limited experiments with friends seem to suggest about half of people can detect this. It's extremely weird to hear sound in this way, in this location. It sounds kinda like you're underwater in a very strange way. It's so hard to describe. It does NOT sound the same as if you heard it with your ears. It doesn't sound like bone conduction. It sounds more like you're blasting sounds directly into the nerves, it's extremely hard to explain, but I suspect you could "hear" all the way past 20khz, I just don't have a cheap way to test it. (I purchased this as a cheap way to test an idea I saw somewhere in the net) These devices blast between 15-22khz. You'd need something fancy to test higher. I think these cheap dog trainers are good because as well as being extremely high output, I suspect they have loads of distortion, either from the electronics or the driver itself, and that distortion will likely fall at a higher frequency than the fundamental, (disruption is typically made of higher frequencies than the fundamental) meaning it proves a little more high frequencies to detect. Again, it's a very odd sensation to "hear" frequencies that I don't normally notice in my friggin neck of all places. One last thing that's very interesting. Electroboom did a video where he electrocuted himself with different frequencies. He found as he approached 20khz, it hurt less and less, and above 20khz, it was hard to detect. I do wonder if 20khz is roughly the maximum frequency that a "normal" nerve can detect? Perhaps there is a lot of losses above that frequent in what is essentially an electrochemical data transmission system (the nerves)? That unless the nerves are placed right next to the brain, the losses are too much to detect frequencies above 15-20khz? Perhaps hearing loss is mainly the deterioration of the cochlear, but also degradation of the frequency response of the nerves themselves? Perhaps placing an ultrasonic transmitter at the base of the skull is vibrating the nerves directly and because of the short distance from there to the brain, it's detected, possibly from a system that may or may not normally deal with sound? Perhaps it is reminiscent of being underwater because high frequency sounds in water would efficiently vibrate and push on these nerves directly due to the uncompressable nature of liquids VS air, which cannot efficiently press on those nerves sure to airs compressability and thus a poor acoustic impedance miss match? Please go down this rabbit hole! Lol
@@Douglas_Blake_579 Perhaps, but given that it doesn't sound very loud, for example the amount of sound I was hearing, I'd compare to speakers playing at around 65-70db, or spent seem dangerous. Of course that SPL estimation is subjective, and only based off comparisons to music and tones, but I'd definitely not call it "loud" by any stretch of the imagination. Around the same volume as the sensation I detect underwater. A quick Google says that high intensity ultrasound is used used therapeutically, and used incorrectly can damage nerves via heat from vibration. These devices however, operate in the power range of around 10-100w/cm². The devices used for dog training are in the mw range, lower than even low intensity ultrasound used for imaging. If it was even slightly painful, or if it was aimed at the ears, then yes, I'd call this careless. Also if ultrasound can be blasted at unborn fetuses without damage at a slightly higher power level, (up to a few watt or so) with track record of over halfa century, i really feel that doing this experiment for a second or two to learn something new about the way our bodies perceive sound should be fine. If you read through the comments, there's a handful of others that have "heard" ultra sound during medical examinations too. I'm not saying its totally safe, but it checks out that it should be fine. In saying that I totally respect if doing something like this makes you uncomfortable, especially if you have personal experience with nerve damage. (asI do) I couldn't fault you for seeing a red flag and posting that comment to warn people to be cautious. It's all good. Each to their own. ☺
I would definitely not expect a dog training device like that to cause any damage, but I also wonder if it's actually testing ultrasonic perception. It may be that the ultrasonic vibrations are exciting the bones of the spine and skull which then create resonances of their own that we're hearing. It's still interesting that you can perceive something and might relate to what was discussed in the study, but it also might be different.
@@PassionforSound it definitely doesn't sound like bone conduction. The dog training device Is not above human hearing, I admit, but the video I saw that demonstrated this used 40khz as the tone and people where hearing it through the back of their head. Weird. I can't remember what that video was though. I'll try to find it
Very interesting indeed! The next step is for an other scientific team to reproduce those results… I’ll be curious to hear what “Audio science review” think about this… ;) . When you say reproduce “live music” experience, you know that 90% of what we hear in a live event is through sound system that are not made to transmit over 20khz? But it is true that when I listen to my live grand piano, it is not the same as any 192khz recording of it. (I have a recording studio). Keep on the good work!
That's a good point about the "live music" thing. I was more referring to a small venue, non-reinforced setup (other than regular guitar amps, etc.) like a jazz club or pub band, but probably should have specified. As for other teams reproducing this, there's a long string of related studies cited in this one that I'll look at for a future video to continue this topic on the channel.
@@PassionforSound No. We can't. I'm 73 years old, my hearing runs from about 40hz to 14khz ... beyond that, nope, nothing. Howeverl we can be affected by ultrasonics ... but that is not the same as hearing them.
Most digital recordings are filtered to 22khz by the DAC's reconstruction filters. Vinyl cartridges seldom get over 16khz. So, there is no reasonable expectation that you have music with embedded ultrasonic content.
That's something that would need to occur in the future, along with more research to understand exactly what level of inclusion is required. For example, having major roll-off of those frequencies might be fine so long as they're not completely removed or maybe the frequency response needs to be flat - I don't know that there's research on that yet. As for the recordings capturing it, high sample rate recordings of 96kHz and above will have the potential to capture those frequencies and native DSD recordings even more so, but the whole recording and playback chains would need to be designed to handle a wider bandwidth before this makes a significant difference for us music lovers.
Audio Jesus! Jokes aside, here's my take on this issue. I began my audiophile journey in 2015. When this next thing happened since then I cannot say but it is going some years back. First I heard that audio on CD's would or do "clip" the high- and low frequencies which are beyond the traditional understanding of human hearing. The reason being was to fit all of the data in the wav files on the disc. "Unnecessary information". More recently I'm hearing reference to a sort of golden "CD-quality" standard. That in an age of streaming and compressed audio, CD quality audio is the benchmark to achieve. This makes me wonder. Is it with the frequencies "clipped" as previously described or is it full range? I am not an audio purist so I do not own or use vinyl or DSD. Do these formats include the full audio spectrum? My intuition has always been that the full dynamic range of the audio should be present for the best sound and here's my reason for believing so. Sound is waves, right? Vibrations that move through a medium. For us humans the medium is gas (atmosphere). For our finned cousins in the oceans, the medium is a liquid - saline water. The medium can also be solid materials. Ever been in an office building when someone is drilling into the concrete walls? Yes, we humans are still using the atmosphere to hear those sounds but the sounds are conducted through the structure of the building. Go ahead and put your ear against the wall. Sure, there's still some air in your ear canal but I betcha you will feel the vibrations on your ear, not only in your ear. So all sound is wave and vibrations. All listening is essentially sound bounced off of reflective surfaces. The size, shape and materials of your headphones and the earpads are the reflective surfaces. For loudspeakers its the dimensions of the room and the surface of every material in it, including what the walls are made of. If we artificially remove the frequencies which are "beyond human hearing capabilities", then of course we are affecting the sound of the frequencies which remain. For a visual representation, think of it this way. Drop two balls of some material into water. Same size, same height, same aerodynamic resistance. Let's assume that all conditions are absolutely equal. One difference: The mass. One is one gram and the other is ten grams. We know that despite the difference in mass that both will fall into the water at exactly the same velocity, 9.8 m/s2 (squared), if all other conditions remain equal.. The more massive object will have more momentum (p=mv) which in turn will generate a more forceful impact (F= delta p / delta t). Further, there will be a larger transfer of kinetic energy (KE= 1 / 2 mv2). As it pertains to sound, when soundwaves encounter obstacles or reflective surfaces in the environment, interference and diffraction of the sounds with a fuller frequency range will have a more complex propagation pattern. So it makes complete sense to me that the findings in this study revealed that people experienced the full-range music as being more spacious. It is quite simply a more accurate representation of what we hear in the real world environment. It's not that we are hearing those frequencies per se but we are absolutely hearing how those to us non-audible frequencies affect the to us audible frequencies and how the sum of these frequencies impact the reflective surfaces in the environment. Basically, vibrations. It would seem that the focus has been too much about human anatomy and too little about physics. Some scientists put headphones on test subjects and played single tones to derive the spectrum of human hearing and concluded "this is it". Strictly speaking in the test environment, yes. But that's "not it" because they forgot to ask physicists. Those who took this audible-range information as gospel made a fatal error. They replaced the real environment with the test environment. They assumed the test environment as the conclusion. So yes, these results make perfect sense to me. Credit to those who created the test environments for these studies. They covered a lot of bases to get richer results. This will have to suffice for now. And no, brevity is not one of my qualities. /Will
_"More recently I'm hearing reference to a sort of golden "CD-quality" standard."_ Do a search for "Redbook CD Standard" ... it's very well documented. _" If we artificially remove the frequencies which are "beyond human hearing capabilities", then of course we are affecting the sound of the frequencies which remain."_ Assuming, of course, those sounds were present in the first place. The vibrational sources in audio are transducers ... speakers and headphones... that covert electrical signals into changes in air pressure; sound waves. This is also very well documented and understood. I agree that we are affected by acoustic vibrations at frequencies we cannot hear, but that does not automatically mean their presence or absence is going to affect the sounds we do hear and it is gross overreach to claim they do in the absence of reproduceable tests showing otherwise.
I'm wondering if what you are referring to as "clipping" is not actually the excessive compression of dynamic range which has been applied since - oh I dunno, I think it started in the late 90s in earnest. If you only got into music in 2015, it's very possible you've never heard an "original" master for cd (or anything else) that has not had all the life compressed out of it, in some cases so much so that indeed there may be audible clipping. But the reason for that is not due to inherent limitations of the medium, it's in service of making the recording "louder" - everything is pumped up and yeah, lots of stuff falls off the table as a result. As someone who started with vinyl and cassettes (my dad even had a reel to reel!), then adjusted to cd, and who now tries desperately to find discs that have not been sonically mutilated...it's absolutely horrid. If you are curious about that, the trend is known colloquially a the loudness wars. You can check the loudness wars database if you want to find releases of a given recording, pre or post compression. Don't get me wrong, in the sense that not all "original" recordings/masters that were intended for cd from the start sound great, a lot of them don't. But I don't know if it's fair to blame cd's per se, vs the musical styles in vogue at the time, and there was a learning curve wrt making a switch from recording for analog (vinyl especially) vs leveraging the increased potential DR of cd.
@@lisar3944 Gotta agree with you on this one. The crappy sound from CDs is not because of the CDs, it's because of the idiot mixing and mastering engineers who use compression and limiting to the max and then turn up the recording levels. As for a CD's capabilities ... they are capable of more than double the dynamic range of Vinyl (95 vs 40 db) far better frequency response (2hz to 22khz vs about 40hz to 18hz) and massively lower distortion (0.001% vs 0.1%). There is no doubt that CDs (and digital files) are the superior medium. It is indeed the loudness wars that are to blame for this. In the 60s and 70s Vinyl releases averaged 15db of dynamic range and less than 1% distortion. In the early 80s CDs were pulling off 40db and 0.01%. When the loudness wars started in the 1990s, CD sound quality took a fatal nose dive... Thanks to garbage mixing and mastering some came out with as low as 1db of dynamic range and as high as 20% distortion. They became an assault on our hearing thanks to demands to be the loudest song on the radio and total disregard for sound quality. Toss in the more recent developments of AutoTune and Quantization making sure every note was exactly on pitch and perfectly timed and you have the recipe for some really really bad music. As you suggest... If people want to know the dynamic range of their favourite CDs they can do a search for "Dynamic Range Database" and look them up there. But be warned... the results can be quite depressing. Can digital (including CD) sound as good as Vinyl? Absolutely. I have a whole bunch of Vinyl I transcoded to digital (mp3/320) around the turn of the century. Once I got the levels right, I could not tell them apart. In A-B testing I often had to look to see which was playing. Today I have thousands of digital music files that sound terrific. I would caution the OP on this thread (@WillieBloom) to do a bit of homework from sources far more credible than online reviews and/or advertising websites. The truth is not always what we think it is.
is this true for both speakers and headphone reproduction? I mean... as the ultrahigh frequency can't be heared with ears that means that are other parts of our body that "feel" them? are the bones in our skull or? because if, for example, is the chest does this mean that the sound via headset has some unexpected limits?
Not really. 90% of the music you hear runs between about 40hz and 8,000hz. Most speakers and headphones can handle that with ease. Plus, unless these ultra high frequencies are encoded into your source material, there's nothing to hear in the first place.
I wish i have an audiophile golden ear so i can listen to every frequencies possible including warm and organic headphone cable that cost $1000 minimum, maybe my ear is not trained enough to listen to all dsd max sample rate albums possible, sadly my ear is only capable of 320kbps damn..
Don't waste your money .... look at the actual frequency spectrum of music... the highest note in standard tuning is 4,100hz (less than 1/4 way up the spectrum) harmonics might reach to 12,000hz or so. But 90% of it will actually be below 5khz leaving the top octave (10khz to 20khz) practically silent. Unless supersonic content is recorded into your source files, which is highly unlikely, there would be simply nothing new to hear.
Super. Interesting- could the older cohort show qualitatively similar EEG changes with the combo of normal frequency and ultrasonic sound exposure compared to younger listeners? I. Other words will ultrasonics help us old deffies!😂
There are a few ... FLAC files set for 96khz can theoretically carry frequencies up to 48 khz ... MQA uses frequencies above 20khz to control some aspects of the file compression and restoration ... But the thing is... nobody can hear any of that and it has virtually no effect on what we do hear. There's a very simple test for this ... set up a blind AB test ... play a song (any song) and then silently turn a 30khz tone from a signal generator on and off... and see how many people can spot the difference... In all likelihood nobody will.
Douglas, you're ignoring the specific studies cited and brain measurements published in this study - I don't get why you're so determined to push back on the evidence on hand? It's true that few recordings will effectively capture the ultrasonic content, but there are many studies (as discussed in this video) that prove the influence of those ultrasonics on our listening experience is both objectively measurable and subjectively preferable. I'm not referring to a single study here, but the body of work in this space. Ralph, DSD recordings are at very high sample rates and should also capture ultrasonic frequencies, but the reproduction of these recordings can still be challenging because our systems aren't all designed to decode and output sound beyond the 20-20,000Hz range.
@@PassionforSound my DAC goes up to 200 KHz, my amp 70 KHz and my Speakers up to 50 KHz, let’s see if the occipital region of my brain gets all excited 😂
Fascinating with interesting potential implications. Ex. Could the activation of further regions of the brain with more high frequency content explain the fatigue some find with all day listening to neutral equipment, and the preference for a treble roll-off? I understand that consumer equipment is limited to 20khz but assume the extra cognitive activity scales with extension. How about the inverse, NOS DACs.. the aliasing creates ultrasonic content that was previously assumed to be filtered out by the ear. How does this effect the subjective experience?
I think fatigue is a different issue (possibly due to timing accuracy and the smearing of timing by excessive feedback, etc. - just theorising). The NOS DAC question is more interesting. If it's getting the timing right AND isn't filtering ultrasonic frequencies, it might just be the most complete sonic experience, but I don't know if any of them are free from some kind of cut-off above 20kHz.
@@PassionforSound but sadly it seems that in practice, many still don't want to do that (a la still wanting to apply heavy compression in favor of "loud"). I recently bought two new releases from artists I respect very much, and they sounded horrid. Looked them up on the loudness wars database and one had an average dynamic range of 9 db, the other was 6 - SIX!!! I just can't
Acoustic music (live orchestras/instruments) will surely have harmonics way above the 20khz cut off on CD or playback equipment. This study might explain why a live performance is more enjoyable and also why listening to CD gives some people physical pain as the body seeks the 'missing' sound. Really interesting, thank you for presenting this.
Actually no. As I explained in another comment almost the entire musical spectrum is happening below 10khz. The highest note in the standard A440 piano tuning is only 4,200hz ...
@@Douglas_Blake_579 That's not altogether true either. The highest pure (fundamental) note that a player can get out of, say, a piccolo is around 5khz as you say, but the instrument also sounds harmonics (as do all instruments) and these can go well over 20khz. The A440 note on a piano is not a pure 440 sound but is made up of multiple harmonics of that note. Correct that the bulk of the sound is the fundamental notes but you need all the harmonics to give character to the sound and those will also interact with harmonics from other instruments.
@@jgsburnett9532 Yep... I get that and in an earlier comment I explained it in some detail. In my experience the average person hears about 40hz to 13khz. The parts that get over 20khz are not going to be heard, to begin with. Much less so when buried in a full on musical performance. Looking at real-time spectrums of music, you will discover that despite common belief, the 10khz plus part of the spectrum is either silent or of such low energy as to be well below the noise floor of both venues and equipment, thus of no real consequence to the final rendering.
Douglas, you might want to watch the video again. The whole point of this study is showing that instruments that produce ultrasonic harmonics will trigger responses in the brain that alter the perception and enjoyment of the music. Although harmonics decline in amplitude as they increase, there will likely be some ultrasonic content in the sound of most acoustic instruments even if it's a very small amount. My suspicion is that it's the influence of the harmonics on the lower frequencies that's making the difference so the ultrasonics need to be present, but their amplitude is probably less relevant.
@@jgsburnett9532 FYI... the 9th harmonic of A440 is at a measly 3,960 hz. Study some specrum plots of actual music... you'll see that above about 10khz there is almost nothing.
Hearing is not necessarily the right word. Just like we can't see all frequencies of light we can feel the heat. Interesting stuff to consider, but doesn't prove much one way or the other yet.
It proves we can receive and react to ultrasonic frequencies. I'd say that's a big step and this is just one study in a surprisingly large body of research.
@@PassionforSound "Hearing" and "Feeling" is quite different. A speaker system has been used in the study; the perception of sound could involve more than our ears. It is quite clear that only hearing bass frequencies in headphones does not reproduce the experience of "feeling" bass frequencies in real life. It could be true for other frequencies, with other part of our body participating to "feel" the sound. I do not know if our ears hear above 20kHz, but maybe other parts of our body can perceive them.
Yes, that's true. We don't know (from this study at least) how those sounds are sensed by the body, but this video wasn't about headphones vs speakers, just sound perception in general.
And see what happens to 40kHz when it hits a hard surface, such as a wall in your room… ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-TQOabMOMGoE.htmlsi=mOOVOi9ylc09mFBc
Interesting! I'm not negating the interest of the video you linked, but in the study discussed in my video, listeners could not perceive any sounds when the ultrasonics were played on their own.
