Missing Fundamental

[LTig]

I can do this, though I can't tell you the pitch. I was in choir in junior high and highschool.



I got it right .

Me too right now - astonishing.

 

[richard12511]

What he's talking about is the inability to distinguish or identify the object. Where there is no percept.

I got that , but what he said brought up a totally separate topic (not related to audio at all) that I've always thought about. I think the novel "The Giver" is what initially put the thought in my head, as a kid. Similarly, how would you describe colors to someone who was born blind?

Sorry, for the OT. Figured I'd do my best to contribute to the thread drift .

 

[Pio2001]

I've not heard this song more than a handful of times in my life.

But I tried to find the pitch of an old song I was listening to when I was young. It seemed to me that it was G minor.
Right ! That was G minor.

Then I tried to remember the pitch of another song that I've heard countless times in the same period of my life (Depeche Mode - Black Celebration)... I was a fourth too high

 

[Francis Vaughan]

What if the "red" I see is not the same "red" that you see? As long as our own color perceptions are consistent within themselves, we could both have totally different images in mind, yet have no way to communicate it.

This is the question of qualia. Been a philosophical question as long as there has been philosophy. However what we can say is that if you agree on all the weird correlations, mixing effects, associations with emotions flavours etc that you are very unlikely to have some different perception or qualia. Occam’s razor would point to having the same.
Unless you are a shape shifting lizard alien overlord. Then all bets are off.

 

[dasdoing]

Me too right now - astonishing.

hehe. I told you.
it just proofs it is trainable, not a "god given" gift.

 

[Pio2001]

Like it! Very accessible to European ears. The guy who entered the stage at the end - is this the composer?

I guess so.

I have just tuned my instrument and recorded two F sharp notes that are two octaves apart.
The lowest F sharp is a course with two strings playing the same note.
The highest F sharp is a course with four strings playing the same note.

I chose them because the highest note sounds a bit out of tune (flat), while the tuner (an Android app) says they are both in tune plus or minus 5 cent.
I makes me want to try the "stretched tuning". It would be interesting to analyze the recording and see if this feeling is caused by anharmonicity or not.

In the file "Double octave", the notes are played one after another so that you can see if they sound in tune for you.
In the file "Solo notes", the notes are played separately so as to be analyzed independently.

If you want to analyze the recordings, it would be interesting to check if the harmonics are perfect multiples of the fundamental, if the Android tuner uses the fundamental or the harmonics to tell that they are in tune, and if pure sines with the same frequency sound in tune or not.

It would also be interesting to draw the +/- 5 cent interval on the spectrum. It represents the accuracy of the tuner.
One cent is 1/100th of a semitone. A semitone is 1/12th of an octave, on a logarithmic scale.
Some other intervals that would also be interesting to see:
22 cent (a comma): an interval that everyone should hear
11 cent: the limit for many people. I can hear this reliably.
5 cent: extremely difficult to hear
1 cent: no human can hear beyond this

The tuner's display is unstable, therefore drawing a spectrogram would be interesting, in order to see if the pitch changes with time.

 

[Duke]

It seems like a few bass speaker manufacturers are making full-range cabinets with quite flat frequency response curves down to 40hz. They're using some modern driver and design technologies. They don't necessarily use big drivers or big boxes, but they require a lot of power. Some players love the sound; others prefer the more mid-centric classic sound. I probably fall into the latter camp, but haven't tried any of these speakers in person.

I just saw that Duke from Audiokinesis is a member here. I'd love to hear his input on this. I'm not sure if his speakers are flat into the bottom octaves, but it's a topic he doubtless knows about. And I think he's friends with designers of many modern bass speakers.

The "target" for my bass guitar cabs (at least the ones currently in production) is the first overtone of low-B, which is 62 Hz. The size/weight/efficiency/cost penalty for delivering the 31 Hz fundamental is enormous.

Most of my bass cabs are "voiced" for electric bass, to "sit well in the mix". My Thunderchild cabs are the exception, being voiced fairly "neutral", and have done well among luthiers, electric piano players, and double-bass players. I even have customers using them for home audio and for tracking monitors.

The competitor who scares me the most is Mike Arnopol, who some of you may recognize as Patricia Barber's bass player... that's just Mike and Patty on her cover of "Ode to Billy Joe" (Choctaw Ridge).

 

[paulraphael]

Most of my bass cabs are "voiced" for electric bass, to "sit well in the mix". My Thunderchild cabs are the exception, being voiced fairly "neutral", and have done well among luthiers, electric piano players, and double-bass players. I even have customers using them for home audio and for tracking monitors.

What does a frequency response curve look like for a typical bass speaker (on designed to sit in the mix)? I've seen lots of plots for amps but not for cabs.

 

[andreasmaaan]

The competitor who scares me the most is Mike Arnopol, who some of you may recognize as Patricia Barber's bass player... that's just Mike and Patty on her cover of "Ode to Billy Joe" (Choctaw Ridge).

Gotta acknowledge, as a business move, that is kinda genius.

 

[Duke]

What does a frequency response curve look like for a typical bass speaker (one designed to sit in the mix)? I've seen lots of plots for amps but not for cabs.

I can only speak for myself, as I don't know what other bass cab manufacturers do.

It took me a while to figure out the voicing strategy that I use now, and imo it's kind of an interesting story (well, pehaps interesting to fellow speaker geeks, at least).

I started working on a bass cab design when the economy tanked in 2008/2009, my theory being that a bass cab is a "tool of the trade", which falls into a different category than the "expensive toys" of high-end home audio. My first bass cabs were voiced like my home audio speakers, as I had no idea "where the goal posts are" for an electric bass cab. Fortunately there was enough of a market for what I was going for me to get off to a pretty good start, but I was well aware that my bass cabs did not sound like "the sound in my head".

So I spent a lot of time reading posts at TalkBass forum to try to figure out where the goal posts are. I came across posts where bass players said they played through a guitar cab and they liked the sound. Aha! I can do that! I made a bass cab with a 12" guitar speaker for the mids and highs, crossed over to a beefy 15" woofer. I sent it off to a beta-tester and what he said was VERY interesting:

He said it sounded great solo, but that he was having a really hard time EQing it to "sit well in the mix".

Duh! It was fighting a losing battle with the guitars over THEIR home turf!! That was one of the best mistakes I ever made, because it told me to go in the opposite direction.

So I looked at the response curves of a bunch of well-regarded guitar speakers, and then "voiced" my cab to "zig" where guitar speakers typically "zag".

What I found was that most guitar speakers have a screaming loud, broad peak between 2 kHz and 4 kHz or so, maybe a bit higher. So THAT region belongs to the electric guitars. A bass cab that's loud there will instigate a volume war with the guitarist, and he can get more volume for a lot less money than bass players can.

Not as obvious but arguably even more important is this: Many if not most guitar speakers have a somewhat narrow dip somewhere in the octave between 1 kHz and 2 kHz, usually closer to the top end of that octave. Imo this dip is a window of opportunity for an electric bass cab: We can have some peakage in this region and it sounds nice and grindy and doesn't step on anyone's toes.

Most guitar speakers are done 5 or 6 kHz, so we can come back up there and get some highs for good definition.

So that's basically what I do in my Hathor and Changeling bass cabs with some user-adjustability included just in case. You can read a review of one of them, with measurements, here:

https://www.bassgearmag.com/audiokinesis-changeling-c112t-bass-cab-real-world-science-fiction/

The thing I focus on the most is actually dispersion, but I needed a good voicing strategy so I'd have something worth dispersing.

 

[dasdoing]

if we hear a song a thousand times we can say when it is in the wrong pitch.

I just learned today this is called the Levitin effect

 

[infinitesymphony]

I just learned today this is called the Levitin effect

This helps me to set a relative key reference all the time. "If I know 'Enter Sandman' is in E..."

 

[Helicopter]

This helps me to set a relative key reference all the time. "If I know 'Enter Sandman' is in E..."

Sad But True.

 

[LTig]

Sad But True.

YMMD

 

[CMOT]

Yes, I know about stretch tuning. But my point about "missing fundamental" still stands.


Human perception is pretty flawed. We see the color yellow when our TV is not capable of making it. Our brain just makes it up. Real yellow exists in nature, obviously, but our brain is doing a lot of signal processing, most of it unconscious.

edit: I think the phenomenon of the missing fundamental should be taught in audiophile school It's the perfect illustration of how flawed our hearing is, how our mind "just makes up" a sound, and only a partial understanding of physics gets one into justifying one's spending habits (e.g. My speakers need to reproduce 16Hz in order to play piano solos).

---

Ack! Human perception is NOT "flawed". It is simply not veridical. Moreover, it is inferential in that it measures physical energy (light, sound, etc.). and then transforms these sensory signals into interpretations of the world. But those interpretations are meant to support robust behaviors, not recreate an exact copy of the physical world as measured. This is true for all sorts of reasons. First, measurement systems are noisy and imperfect, but our perceptual processes make it possible to infer beyond the specifics of the sense data. This allows us to survive because - for the most part - these inferences are reasonable (e.g., based on statistical regularities). Second, sensory data is not organized into the kinds of things that matter for behavior - objects, actions, etc. - so there is a progression of interpretation leading up to "high-level" structures that represent meaningful things in the world that we need to act on or interact with. Often this means making inferences from measurements that transform the data in non-linear ways. To take the color example, ALL colors are "made up" by our brain. The only physical things in the world are wavelengths of light - but wavelengths are never color. Color is a purely perceptual phenomena in which our short, medium and long wavelength cones (which are the retinal light receptors that support color perception) each respond differently depending on the current input wavelengths. And the cone responses are continuous functions across wavelength - not punctate measurements at a single wavelength. Then the cone responses are recast in terms of three opponent systems - light/dark, red/green, and blue/yellow. The responses for every color are determined by how much light energy is present in each of the three cone channels that feed into the three opponent systems. Red/Green is fed almost purely by medium and long cones in opponency, while blue/yellow is fed by opponency of short vs a combination of medium and long. Your TV produces different wavelengths of light in proportion to generate the desired responses in the these three systems.

Similarly, your mind/brain doesn't "just make up a sound" - if we think of perceived sounds as being like color, there are only wavelengths of waves traveling through a medium that impinge on our eardrums. Our auditory system turns these into perceived sounds, but sounds are really only entities that roughly map to physical stimuli - the sounds themselves are psychological. After all, what is pitch? There is certainly isn't a 1-to-1 correspondence between perceived pitch and any sensory inputs.

 

[paulraphael]

This helps me to set a relative key reference all the time. "If I know 'Enter Sandman' is in E..."

Has anyone developed absolute pitch by using their tinnitis as a reference? Maybe I'll turn this into a magic trick.

 

[rdenney]

I could do that, but only if the pitch I’m trying to match is about 11-12 KHz.

Given that I’m a tuba player, that’s a couple of orders of magnitude too high.

Rick “whose pitch sense is excellent in some contexts but really sucky in others, with no apparent pattern” Denney

 

[CMOT]

This is a complete left field hijack - but that is a slightly flawed idea of how colour perception works. Our eyes intrinsically cannot differentiate pure spectral yellow from a combined set of wavelengths. Hence tri-colour vision theory. Even in nature your eyes cannot differentiate a mixed yellow from a pure yellow. This isn't part of how the brain works. It is already welded into the signals the optic nerve sends back to the brain. The brain "sees" in Lab colour. There is pre-processing of the colour occurring in neurons in the back of the retina, these take the stimulus from the colour sensors and perform a simple convolution, yielding Lab. As a really cool bit of neurophysiology, some time back a group of researchers reverse engineered the retina's function from study of the actual interconnections, and indeed, it exactly matched the previous empirically derived function. Very very cool.

As to the missing fundamental versus real fundamental, this is indeed the ear-brain system processing. Just where it occurs is open to debate. The ear operates with real time feedback from the brain (unlike the eye.) So there are all sorts of places the missing fundamental could come from.

[ETA, below - this is perhaps subsumed by @JIW 's post above, but reaches the same conclusion.]

I found another recording of the Imperial Bösendorfer, and it is perhaps more revealing. The fragment explicitly tried to emphasise the low keys. The spectrogram clearly shows that the recording itself is capable of carrying the low energy, as there is a very deep bass at about 22Hz. Possibly due to general thumping of the instrument. Tellingly there is a clear peak at about 25Hz, which matches a dominant peak at 50Hz. But it is well down in amplitude. I would conclude that there is some real energy at the fundamental, but it is, as one would expect, well down in amplitude compared to the second harmonic. Even a 9 foot grand is going to have significant trouble reaching 25Hz. The sound must come from the sounding board, and the Q of that would need to be so low as to make it floppy, just to get it to get moving much at those frequencies. Something that would wreck it for the rest of the notes. Maybe if someone built an 18 foot grand.

View attachment 102513

Almost right, but "Even in nature your eyes cannot differentiate a mixed yellow from a pure yellow" is still misleading. There is NO yellow in nature. There are only wavelengths of electromagnetic energy. Some specific wavelengths and some combinations of wavelengths are perceived and labeled (in most cultures) as "Yellow". But nature knows nothing of colors. That is all in your head. Sometimes people find this less confusing if you think about the sensation of pain. No one would argue that pain exists in nature. Pain is our psychological interpretation of particular kinds of physical stimulation to our bodies. Through evolution, our brains have decided to label those signals as "painful". But pain is just energy (e.g., heat) or a state of some part of our body (e.g., broken). Color and sound are the same thing. We measure energy in the world - in EM energy or in the air - and then turn that into an interpretation of the physical world. Those interpretations are precepts - color, sound, pain, things etc.

 

[infinitesymphony]

Has anyone developed absolute pitch by using their tinnitis as a reference? Maybe I'll turn this into a magic trick.

It's possible. Because tinnitus is caused by permanent bending of the cilia that correspond to certain frequencies, it stands to reason that tinnitus caused by loud music over time might lead to ringing at A440-tuned pitches and overtones.

The other factor is that the inner ear, being fluid-based, is subject to the same changing conditions as the rest of your ENT system. When you get a cold or have allergies, your pitch perception might change.