T60 Limit

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SethRocksYou
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Re: T60 Limit

#46 Post by SethRocksYou » Sat Aug 25, 2018 12:18 pm

Ryan A wrote:
Sat Aug 25, 2018 11:10 am
I agree with most of what was said in this thread. However regarding hearing of 20-25 hz, it’s completely normal (if you still have all your hearing left) to hear those frequencies. There is a big difference between 25 and 50 hz for sure. Good earbuds for example do work at 20 hz (and with very low distortion at that) regardless of the sonic wavelength even though they are but a few mm or cm from
your eardrums.
That's the book knowledge I have always known to be true too. The earbuds I use aren't anything special and I can make out sine waves down to 16, where it starts to play games with my perception. Coming in and out of a perceivable sound right around that mark. That said, I have a high level of trust and regard in/of Bills knowledge. So, I have to question myself, what I think I know, and what I think is true. Is it technically possible for overtones to present themselves to being heard in the shape of the fundamental? I have no idea. I do enjoy challenging and expanding my knowledge though.

Hopefully my earbud test microphone rig will shed some light on the subject.

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Bill Fitzmaurice
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Re: T60 Limit

#47 Post by Bill Fitzmaurice » Sat Aug 25, 2018 1:25 pm

Google 'missing fundamental' . Also read this: https://www.google.com/url?sa=t&rct=j&q ... zznNEAZGT5

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Re: T60 Limit

#48 Post by Rich4349 » Sat Aug 25, 2018 1:35 pm

Ryan A wrote:
Sat Aug 25, 2018 11:10 am
... try playing music that has sub 40 hz content with a T39 high passed at 45 and all you’ll hear is harmonics of course, because you’ve cut off the fundamental and it sounds like garbage...
Shouldn't the folds of the horns in tubas or titans be removing those harmonics? Or is there just enough of them left to be heard, though at reduced levels?
Last edited by Rich4349 on Sat Aug 25, 2018 7:10 pm, edited 1 time in total.
2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!

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Re: T60 Limit

#49 Post by SethRocksYou » Sat Aug 25, 2018 2:15 pm

Rich4349 wrote:
Sat Aug 25, 2018 1:35 pm
Ryan A wrote:
Sat Aug 25, 2018 11:10 am
... try playing music that has sub 40 hz content with a T39 high passed at 45 and all you’ll hear is harmonics of course, because you’ve cut off the fundamental and it sounds like garbage...
Shouldn't the folds of the horns in tubas or titans be removing those harmonics? Or is there juts enough of them left to be heard, though at reduced levels?
Harmonic distortion from the driver gets filtered. The harmonics of an instrument are what makes the instrument sound unique and different than all other instruments. An example of what he's saying is the 5 string bass will play down to about 30hz. That 30 is the fundamental of that note and it's accompanied by harmonics that make it sound distinctly like a bass guitar. If you played that note through a system that's high passed at 40 or 45hz, obviously the fundamental frequency will not get amplified, but all the harmonics that make up the sound above the high pass will still get amplified and will be heard just fine. Unfiltered by the horn.

I think this is essentially the "Missing Fundamental" Bill mentioned above. Which, I don't think applies to a sine wave. But, I'm still learning.
Last edited by SethRocksYou on Sat Aug 25, 2018 4:29 pm, edited 2 times in total.

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Re: T60 Limit

#50 Post by SethRocksYou » Sat Aug 25, 2018 2:28 pm

Bill Fitzmaurice wrote:
Sat Aug 25, 2018 1:25 pm
Google 'missing fundamental' . Also read this: https://www.google.com/url?sa=t&rct=j&q ... zznNEAZGT5
I appreciate the direction. Let me dive in this rabbit hole. If I'm not back in a day, send help. LOL

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Re: T60 Limit

#51 Post by Bill Fitzmaurice » Sat Aug 25, 2018 3:14 pm

SethRocksYou wrote:
Sat Aug 25, 2018 2:15 pm
I think this is essentially the "Missing Fundamental" Bill mentioned above. Which, I don't think applies to a sine wave.
It can, under the right circumstances. The Klipsch link in part explains how. Other sources go even deeper into the effects of modulation distortion.

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Re: T60 Limit

#52 Post by SethRocksYou » Tue Aug 28, 2018 12:35 pm

Bill Fitzmaurice wrote:
Sat Aug 25, 2018 1:25 pm
Google 'missing fundamental' . Also read this: https://www.google.com/url?sa=t&rct=j&q ... zznNEAZGT5
So, I've researched and read through those a few times. I'm not exactly sure what I've gained.

The Missing Fundamental made sense. I found it especially interesting that: "This very concept of "missing fundamental" being reproduced based on the overtones in the tone has been used to create the illusion of bass in sound systems that are not capable of such bass". Quoted from: https://en.wikipedia.org/wiki/Missing_fundamental

Makes me wonder if there's something like that in my computer, which is what I have my earbuds plugged into. That said... I think I'm a reasonably intelligent guy with fair deductive skills and a reasonable connection with reality. I'm still not dissuaded. I still believe that I'm hearing down to 16hz. However, I am still open to being wrong about that.

I wish there was a bit more context to your recommendation of reading and research. Even having it as a response to a quote would give me some framework and a point of view to "listen" from. I say this, because the Klipsch read was a tough one to follow, for me. Was there something specific in there you were wanting me to see?

Here's what I was able to pull out of it. Horns have less distortion that direct radiators. Frequency Modulation and Amplitude Modulation are forms of Modulation Distortion.

I thought I'd find something that ties into the Missing Fundamental. Possibly indicating, that in some cases, it's distortion that one hears instead of the fundamental tone. I didn't see it. Although, I have to admit, I got kind of lost in it all. Lost in both, the antiquated writing style and content that is beyond my current ability to comprehend. Was there something specific in that, that you wanted me to see? If so, would you mind paraphrasing it for me? Even indicating a page and paragraph to inspect closer would be helpful.

I'm very grateful for any and all direction and information Bill. Thank you.

-Seth-

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Re: T60 Limit

#53 Post by Bill Fitzmaurice » Tue Aug 28, 2018 1:20 pm

There's nothing easy or intuitive about this, you're delving into post-graduate level stuff. As for hearing 16Hz, would you think you were hearing 16Hz if you weren't aware that there's possibly 16Hz content there? Since your opinion is purely subjective the only way to test it is via double blind testing.

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Re: T60 Limit

#54 Post by Bruce Weldy » Tue Aug 28, 2018 1:55 pm

I often illustrate how our brain fills in what we want to hear even when it's not there.

I play a standard D chord on a guitar tuned to standard E tuning, playing the chord while walking down the bass notes. Since there is no D available after the low E on the walk, I play a full D chord with an F# on the low E string. It sounds like there is a low D present even though it's impossible. It kinda' makes me smile every time I do it, because even though I know whats happening, my brain still wants to fill in the missing note.

I would say that a huge percentage of the time, that's what people think they are hearing - but it just ain't there.

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Re: T60 Limit

#55 Post by Ryan A » Tue Aug 28, 2018 2:07 pm

Don't let confusing papers and complicated words dictate your perceptions. This topic got me curious anyway.

Try downloading a tone generator like NCH, its free to try. Set it up for 16 hz with a good pair of headphones or ear buds. You can then overlay more sine waves on top of it. Try playing 16, 32, and 64 hz all together. When all 3 are played together, only 64 hz is perceptible to my ears (YMMV). Remove 64 hz, and you hear the 32 hz mostly. Remove 32, and you still hear the 16hz (the fundamental) if you got good ears. If you can't tell the difference, you got problems with your hearing or just can't hear what other people can. Cheers.

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Re: T60 Limit

#56 Post by Bruce Weldy » Tue Aug 28, 2018 2:36 pm

I guess the question that's hard to answer is: at what point are we longer hearing, but feeling?

With headphones or earbuds, if the driver can move the cone at 16hz, you are definitely going to feel it in your ear canal.....does the brain fill in the "sound" or are we actually hearing it? I don't know the answer.

I would guess the only way you could test it would be to somehow suspend yourself in mid-air while the tone plays through a speaker. Although you'd still be struck by the sound wave, at least you wouldn't be getting vibrations through your feet.

Since our perception of sound is entirely based on vibrations in the air - where is the cut-off between feeling and hearing? Obviously, not a problem with high frequencies since it's much harder the feel the vibration with anything in your body other than the ear.

Interesting.......

But quite honestly, it means diddly-squat in the real world of sound.....unless you are into special effects, I guess..... It sure isn't going to be doing anything worthwhile in music.

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Re: T60 Limit

#57 Post by Bill Fitzmaurice » Tue Aug 28, 2018 3:06 pm

Ryan A wrote:
Tue Aug 28, 2018 2:07 pm
you still hear the 16hz (the fundamental) if you got good ears.
The assumption is made that since there's no 32 and 64Hz in the signal then what you hear must be 16Hz. That assumption doesn't account for the basic operating principles of moving diaphragm transducers. If you remove the overlaid 32 and 64Hz tones there will still be 32 and 64Hz present, albeit at lower levels, as the headphone diaphragms create it. There will also be 3rd harmonic content at 48Hz, and all of the higher harmonics as well, though the 2nd, 3rd and 4th will dominate. Even though the 32 and especially the 48 and 64Hz harmonics are at far lower levels than the 16Hz fundamental they're still what you hear, due to equal loudness.

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Re: T60 Limit

#58 Post by Ryan A » Tue Aug 28, 2018 5:05 pm

Bill Fitzmaurice wrote:
Tue Aug 28, 2018 3:06 pm
Ryan A wrote:
Tue Aug 28, 2018 2:07 pm
you still hear the 16hz (the fundamental) if you got good ears.
The assumption is made that since there's no 32 and 64Hz in the signal then what you hear must be 16Hz. That assumption doesn't account for the basic operating principles of moving diaphragm transducers. If you remove the overlaid 32 and 64Hz tones there will still be 32 and 64Hz present, albeit at lower levels, as the headphone diaphragms create it. There will also be 3rd harmonic content at 48Hz, and all of the higher harmonics as well, though the 2nd, 3rd and 4th will dominate. Even though the 32 and especially the 48 and 64Hz harmonics are at far lower levels than the 16Hz fundamental they're still what you hear, due to equal loudness.
Not making any assumptions. I hear what I hear. You couldn't convince me the dog I'm looking at is a cat just because you're a veterinarian. Cheers.

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Re: T60 Limit

#59 Post by BrentEvans » Wed Aug 29, 2018 10:21 am

Ryan A wrote:
Tue Aug 28, 2018 5:05 pm
Not making any assumptions. I hear what I hear. You couldn't convince me the dog I'm looking at is a cat just because you're a veterinarian. Cheers.
Respectfully, you are indeed making assumptions. You are assuming that you have heard true content in these frequency ranges, and that you know what it sounds like. You are assuming that your experience is hearing sound pressure rather than feeling air pressure. You are assuming that your reproduction devices are accurate. You are assuming your knowledge is complete.

To use your metaphor, if you had never truly identified which was a dog and which was a cat, and believed a cat was a dog because that's what you'd always been told or assumed, you might reject the truth told to you by a vet in favor of a false perception. You might not believe a vet just telling you, but if a vet is pointing you toward outside references generally accepted by the rest of society and asking you to test your knowledge and perceptions according to those references, you would find through that process that what you're indeed seeing is a cat, not a dog.

Have you ever had your assertions tested in a double-blind scenario, as was mentioned earlier? Using the testing method you described, where you are in control of the test parameters, you are subject to confirmation bias. It would also be interesting to see an analysis of the actual frequency content you are hearing. There is a difference between natural harmonics, which ALL electromechanical reproductions have, and layering in generated harmonics. The effect would be completely different.

Further, if you are listening in earbuds or headphones, you are experiencing a different pressurization method than real world sound. With both ears receiving an identical signal but being pressurized from different directions, you are certainly more apt to perceive that signal from the sheer air pressure. Experiencing that effect is not the same as hearing the frequency. If you were to produce a similar SPL at your ear from a distant point source somehow devoid of all natural harmonics and reflections, your ears would experience the sound pressure, but not the air pressure. You would perceive that very differently, and perhaps not at all, depending on the circumstances.

To not be willing to test your knowledge, thereby admitting the possibility that you might be wrong, is basically the same as egotism. Basically what you are saying is that you know more or better than everyone else. That type of attitude won't get you very far in life, unfortunately.
99% of the time, things that aren't already being done aren't being done because they don't work. The other 1% is split evenly between fools and geniuses.

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Re: T60 Limit

#60 Post by Bill Fitzmaurice » Wed Aug 29, 2018 10:43 am

It could get you elected President. :wall:

Got to go now, I'm late for my Flat Earth Society meeting.

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