Is the "blue note" overblown in importance?

[CharlyG]

Carol Kaye calls the b5 a passing tone... Good enough for me, since she was a jazz guitarist before switching to the bass,...

 

[Neer]

Carol Kaye calls the b5 a passing tone... Good enough for me, since she was a jazz guitarist before switching to the bass,...

That is not what a blue note is, though.

 

[arthur rotfeld]

The b5 is typically used as either a passing tone, neighbor tone, etc, even appogiatura, to inflict Western classical on the issue. We don't hear too much leaping in and out of it.

 

[fenderlead]

These are all great points.

Firstly, there is African music that sounds close enough to blues to possibly share some kind of ancestral link: mostly from West and North Africa, not Central or South Africa, which would make sense as most slaves were taken from the West and North. (The above article seems to be talking about instruments from Central and South Africa - very different cultures from the North, which has strong Islamic influence.)
However, it's hard to remove the Western influence from the music of (say) Ali Farke Toure or Tinariwen. Obviously they play electric guitars, and equally obviously they've heard American blues and popular music, and it's hard to tell how much of their African heritage they've retained. The best we can say is that they clearly feel a natural affinity with blues, as if they do recognise something familiar in it, at least with the one-chord blues of John Lee Hooker. They're clearly not just copying American music, but producing something with a still very African sound.

But African-American music obviously drew from many sources. Slaves were frequently banned from indulging in African musical practices, in case it encouraged solidarity and rebellion (an exception being New Orleans). So they naturally attempted to apply their musical instincts to the European music they heard. Certain kinds of British and Celtic folk music have a lot in common with African folk forms, in particular (interestingly) the so-called "neutral 3rd", which is neither major nor minor, but somewhere in between - not fixed, but movable by the singer for effect.
IOW, just as Ali Farke Toure heard a distant cousin in John Lee Hooker, 19th century slaves would have heard familiar-sounding melodies in old English folk tunes like "Pretty Polly" (a 12-bar form, incidentally, and mostly minor pentatonic).
Meanwhile, Scots melodies would have led to the major pentatonic spiritual and gospel forms, also adopted eagerly by slaves and their descendants.

Blues can, of course, be crudely described as a blend of parallel minor and major pentatonic, with melodies pulled around between one and the other.

The northern parts of Africa are obviously more Muslim and so there is what I call that Middle Eastern influence going on which is very different to say Zulu music from the south of Africa.

Some of that Middle Eastern chanting (or chanting derived) and drone instruments made it's way into Flamenco I would say.

Some of that is in the Blues, but the Blues is different in a lot of ways and the Blues has chanting but it's not that Middle Eastern style and Flamenco singing has more of that Middle Eastern style than the Blues does.

The Blues is using European harmony and there is chanting going on that is probably derived from northern Africa but it's within the I7 IV7 framework especially and seeing that Middle Eastern (Northern African) music has a tendency to wander a bit and not have all of the notes being totally precise, then note wandering between the I7 and V7 and mixing them up is just another case and then some preferred patterns emerge such as the Root b7th and 5th of the 17 and the Root b7th and 5th of the IV7 make up the minor pentatonic and the minor pentatonic in the Blues case is not isolated on the I7 but spread out over the I7 and IV7 and there can be non precise pitch alterations going on as derived from the Middle Eastern way but they are centered around the Root b7th and 5th of the 17 and the Root b7th and 5th of the IV7 which just so happens to also be the minor pentatonic spread out over the I7 and IV7.

Some interesting things


http://en.wikipedia.org/wiki/Ngoni_(instrument)

http://en.wikipedia.org/wiki/Mandé_peoples

http://www.ngoni.org/#!info/cve8

http://www.dailymotion.com/video/x4hr85_donso-ngoni-sekouba-traore-ortm_music

https://vimeo.com/77031372

 

[kimock]

But our harmonic system is based on 5-limit intervals (or close approximations to them). 7-limit is not considered because its too out of tune. Chords built using those pitches would not work the way we mostly like chords to work - in progressions in keys, with the potential for modulation (without retuning).
For 7th partials to have harmonic use, we'd need a different harmonic system, and maybe a totally different set of octave divisions (more of them, or highly irregular ones).OK, but that's a 35:24 ratio with C. Why not just go for a 7:5, surely a more likely ratio? And much closer to the midway point between P4 and P5. Why - if the keynote is C - go down to A in order to come back up?
This is all very well, but how do you then explain the most common blue 3rd which centres itself somewhere between 6:5 and 5:4?
There is no simple 7-limit ratio that applies in that space.
The only thing that can explain that note, seems to me, is the idea of "something somewhere nebulously in-between" (between either two ET pitches or two just ones, take your pick). Or as I prefer to see it, as a variable pitch region, not fixed to anything at all.
I guess it may well be pulled (intuitively) in two directions, by 5:4 at the top end and 6:5 (or even 7:6) at the bottom end, but the distinctive thing about the "blue 3rd" is its very mobility. You certainly don't hear blues singers singing any of those pitches dead on and holding them, for long enough to be sure exactly what pitch they're thinking of.
The 7th partial theory is appealing in some ways (certainly regarding the blue 7th at least), but it's hard to see how we could get evidence for it from actual blues performances, where singers never seem to settle long enough on any note (other than chord tones) for them to be actually measurable.

This is one problem with the western scientific approach to music and scales. We seem to want to identify specific frequencies or specific ratios; to pin down some fixed pitches. Obviously if we want to make connections to the harmonic series, that's essential. But blues is not like that. Singers and players bend their notes around - that much is obvious. We can't measure the frequencies they're producing when they never stay still long enough; but more to the point, why should we want to, when it's the movement that is clearly the point?

Obviously there are fixed pitches in the immediate environment (chord tones, tuned more or less to ET), and - in the vocals - I wouldn't deny a sense of gravitational pull to tonic and 5th at least; and possibly 4th too. There may also be cases of a blue 7th held long enough to suggest it might be 7:4, and maybe figures can be obtained to show it's nearer that than it is to a tempered m7, or to a just 9:5 or 16:9.
But the blue 3rd - I don't see how that's going to get pinned down to one "ideal" pitch. One might suggest 7:6 and 5:4 as its outer limits (I'd be OK with that), but that hardly explains the fondness for something between 6:5 and 5:4.
Maybe that's just some kind of attractively "unstable equilibrium"?

Jeez. .
"Fixed pitch" is an instrumental reference, you would never even consider the term in relation to voice, so no, anything sung is by definition not fixed pitch.

Whatever the pitch is, "blu third" by your definition, or any location on the continuum of the octave, if you don't ID it and commit it to a tuning or a temperament it's "not fixed".

That doesn't mean it "moves around" or it's "mobile", it just means you haven't gone thru the considerable trouble to nail it down and commit it to a small, limited system of tones for use harmonically. Chords. .

If it's recognizable as pitch at all, it's not in two places at the same time, so while I get where you're coming from and think it's fine for you to think like that, you're missing the point that "fixed pitch" requires that pitch to have multiple meanings.

You just have a temperament based perspective. .

You could easily nail down blu third from that perspective, it's the bisection of the fifth. Done. It's in the system, it's a quarter tone.

The flip side being we don't really hear like that, by "mean", or mid-way point.
Audible, harmonic mediants are more likely some product of the harmonic weight of their end points regardless of interval size.
The Noble Mediant of the the fifth is probably 4:3, not the physically equidistant 1/4 tone.

Anyway, pitch, as melody unfixed by temperament doesn't "move around" except when viewed from the perspective, lower resolution, and rules of temperament.

It still "plays by the rules" if it's going to be heard and sung or played, it's just playing by different rules according to tempo, tonic, relative tuning in the rest of the harmony, and splitting the differences between chord tones, lingering melody tones, scale tones, direction of the line, and "local intonation" intervallically.

Taken on its own terms, melodic intonation doesn't abide by the one-size-fits-all perspective of temperament, or harmony in general terms, it's just a different trip.
It's complicated. .

But you'd have to approach it on its own terms to see that, and you can't do that without hands-on microtonal torture.
The whole thing "scales", the ideas of rules and function, "use this not that", "these go together", the interrelatedness of tones doesn't stop or exist only at the 12 tone level.
It keeps right on going, no matter how small you chop it up.

If it's music, if you're feeling it, it's functioning.
If it's functioning, it's behaving in some kind of "this, not that" fashion.
That requires specificity at our normal 12 tone level, and not surprisingly, greater specificity when you add more tones.
And yeah, sure, it looks like a whole bunch of random **** from the perspective of the piano keyboard, but that's exactly what the piano looks like from the perspective of pure melody.

The polarities involved are basically "note" and "meaning".
You're looking at meanings which employ a great many notes from the perspective of a system which uses one note for a great many meanings and scratching your head.
You could reconcile that, but you'd have to actually cave in and study it from the other perspective.

 

[CharlyG]

That is not what a blue note is, though.

I never said it was, and I don't believe it is against the rules to speak of surrounding subjects that pop up in a thread.

 

[dirk_benedict]

Yeesh, we only have 12 notes as it is and you want to get rid of one??

Ok, fine...but I'll need to acquire another low-gain OD or delay pedal to make up for it? Deal?

 

[JonR]

Jeez. .
"Fixed pitch" is an instrumental reference, you would never even consider the term in relation to voice, so no, anything sung is by definition not fixed pitch.

Whatever the pitch is, "blu third" by your definition, or any location on the continuum of the octave, if you don't ID it and commit it to a tuning or a temperament it's "not fixed".

Right.

That doesn't mean it "moves around" or it's "mobile"

We're clearly using the same words to mean different things here.
If a sung note is not fixed, then surely it moves around (or is capable of moving anyway). If it doesn't, that means it's fixed.
Yes? No? Help me out here....

, it just means you haven't gone thru the considerable trouble to nail it down and commit it to a small, limited system of tones for use harmonically. Chords.

OK.
I can see that fixing pitches is right for chords. That "small limited system of tones".
What about blues vocals and (by extension) improvisation? Blue notes?
Should we nail those down or not?
If not, what's all this business about 7th partials? If sung pitches are by definition "not fixed" (and I'll certainly agree with blues), why the need to find fixed reference points (outside the chords)?

If it's recognizable as pitch at all, it's not in two places at the same time

Quite - I wouldn't say it was!

, so while I get where you're coming from and think it's fine for you to think like that, you're missing the point that "fixed pitch" requires that pitch to have multiple meanings.

OK, this is probably semantics, because I'm not sure what you mean here.
In what way can a fixed pitch have multiple meanings? Do you mean in relation to different reference points? (chord roots, eg?)

You just have a temperament based perspective.

You could easily nail down blu third from that perspective, it's the bisection of the fifth. Done. It's in the system, it's a quarter tone.

But why would I want to nail it down? That's what I don't get.

I like the idea of the bisected 5th, but I don't see it (or hear it) as an exact point. I'm not sure that's what I'm hearing. (I guess it might be, I just don't know how, mathematically, a bisected 5th would work)

The flip side being we don't really hear like that, by "mean", or mid-way point.

Ah-ha....

Audible, harmonic mediants are more likely some product of the harmonic weight of their end points regardless of interval size.

Now that sounds interesting. It seems to align with what I was saying about "unstable equlibrium", a tension between two points.
What do you mean by the "end points"?

The Noble Mediant of the the fifth is probably 4:3, not the physically equidistant 1/4 tone.

I'll need that explained. What's a "Noble mediant"? and 4:3 in relation to what?

Anyway, pitch, as melody unfixed by temperament doesn't "move around" except when viewed from the perspective, lower resolution, and rules of temperament.

It still "plays by the rules" if it's going to be heard and sung or played, it's just playing by different rules according to tempo, tonic, relative tuning in the rest of the harmony, and splitting the differences between chord tones, lingering melody tones, scale tones, direction of the line, and "local intonation" intervallically.

I see all that (I think), but all I mean by "move around" is the normal way we bend notes in blues, in that they don't settle on fixed pitches (or do so rarely). If they do settle on an identifiable pitch, they spend longer on the moving up to it, or away from it.
I'm not saying that the target pitches, the reference points, move around. Obviously they can't. I'm only talking about the flexibility of blues vocalisation; the fact that - for example - it's about as far from the sound of auto-tune as you can get.
Auto-tuned vocals are an example of singing which doesn't move, and (thereby) sounds unnatural. (Not because it's tempered, but because it sticks to pitches in a stepped fashion, and doesn't swoop between them.)

I'm not talking about some intuitive hearing of 7th partials that might make reference points for blues vocals. That might be possible, and is theoretically interesting, but I don't hear reliable evidence for it in the music. (because the notes move around too much....)
I mean, I can make all the sense I need to make from blues by copying the sounds, and relating them to what I actually do hear.

The polarities involved are basically "note" and "meaning".
You're looking at meanings which employ a great many notes from the perspective of a system which uses one note for a great many meanings and scratching your head.

I don't think I am, personally, and I'm probably not explaining myself very well.
I'm not scratching my head about blues and how it works. I think I understand it well enough as sound, and certainly don't feel any need to nail it down to 12-TET. I know it works outside of (or in between) that.
It's true I'm using language based on 7-note scales, in talking about "3rds" and "7ths".
When I say the blue 3rd "moves around", or is a "pitch region", I mean that's what I hear in the music, and how I get it to sound right when I'm playing. I'm not aiming for 7:6, 6:5 or 5:4, because I don't hear blues singers or players doing that. Or rather, maybe they do aim for one of those, but they spend so long getting to it that it's that bending that seems like the point to me, not the target. ("The journey not the destination", haha )
When I do hear "resolution" - pitches coming home to a target - it's to chord tones (or near enough anyway).

Obvioulsy I haven't subjected myself to what you call "hands-on microtonal torture". I wonder how many of our blues heroes did that...

 

[fenderlead]

That's what's wrong with the blues, it needs auto-tuning.

 

[CharlyG]

I like the journey not destination bit.....

 

[guitarjazz]

That's what's wrong with the blues, it needs auto-tuning.

Finally, some common sense.

 

[Motterpaul]

I think I see what you are saying, essentially that "the blue note" as defined by a flat5 is no more expressive than any other chromatic note, and hence does not deserve the lofty title of THE blue note. The tension that it creates, however, cannot be matched by any other chromatic tone in a blues progression IMHO.

First, I have to read up on 7th-partials. Anyway, yes, this is what I meant, it is like any other passing tone we typically play in "blues".

As far as music theory having rules goes - When I took music theory classes it had VERY strict rules, almost like English grammar or math. A given particular movement DEMANDED a specific response. But I am referring to the classic four voice chorale harmony most of us studied if you were a music major at any time. I had two years of it. I think it is good to know and understand music theory as a language for communication, but I think there are far more advanced and applicable ways to define the theory of contemporary music (extended jazz chords, for example).

I actually truly believe and wish music theory could "start over" and that many of the old rules could be replaced with new rules. That is almost a new thread topic "Music's New Rules" - one example would be "how many different forms of the blues scale exist and when do you use each one?" - another would be "chord substitutions for accompanying a melody".

Also - just to note that this "mystery" of the "blue note" is not just in my mind. It has tripped up deeper thinking musical theoreticians than myself. Here is an article where the author starts to dig into the specific topic, but while he finished the web site, never finished his article about the "blue note": ("Examples coming soon." he left it saying)

http://legacy.earlham.edu/~tobeyfo/musictheory/Book1/FFH1_CH3/3L_TheBlues.html

And when it comes to rules, consider just page ONE of the same person's book #2:

http://legacy.earlham.edu/~tobeyfo/musictheory/Book2/FFH2_CH3/3A_ChordVoicingDoubling.html

[examples of his rules below]

As a general rule, simply do the following:

Be certain that the soprano and alto voices are closer than an octave to each other.
Typically, allow no more than a sixth between the two.
Do not allow the tenor voice to stray lower than a seventh below the alto, and again, typically, no more than a sixth.
The bass voice may range freely. When it is closer to the tenor, then the alto and soprano should not range too far away.
Think in this case that the bass represents the second, third or fourth partial. The upper voices are relatively close to the lower voices.
When the bass ranges away from the tenor voice — and it is perfectly OK for the bass to be a tenth or even a twelth away — there is a greater ability to expand out the voices, as in the model of the harmonic series.

And more rules:

Here is the basic principle, recognizing that exceptions are often to be found within certain harmonic contexts.

1. Root position triads. Double the root of the chord, which is the same as saying double the bass note.
2. First-inversion triads. Double the soprano, regardless of which voice it represents.
3. Second-inversion triads. Double the bass, which is the same as saying double the fifth of the triad.
4. First-inversion diminished triads. The diminished triad appears most often with the third in the bass, so as to avoid the tritone between the actual root of the chord and the upper fifth. When voiced in this way, double the bass note, which is the same as saying double the third. Thus the tritone is only represented by one voice, and the more stable third is represented by two.
5. Seventh chords. Regardless of inversion, distribute the four notes of the seventh chord, of any type, to the four voices, observing smooth voice leading. Occasionally, especially with the dominant seventh chord, the fifth can be omitted and the root doubled.

 

[guitarjazz]

Someone wrote a good book about playing the blues. Check it out:
http://www.shermusic.com/new/1883217385.shtml

 

[JonR]

First, I have to read up on 7th-partials. Anyway, yes, this is what I meant, it is like any other passing tone we typically play in "blues".

As far as music theory having rules goes - When I took music theory classes it had VERY strict rules, almost like English grammar or math. A given particular movement DEMANDED a specific response. But I am referring to the classic four voice chorale harmony most of us studied if you were a music major at any time. I had two years of it. I think it is good to know and understand music theory as a language for communication, but I think there are far more advanced and applicable ways to define the theory of contemporary music (extended jazz chords, for example).

I actually truly believe and wish music theory could "start over" and that many of the old rules could be replaced with new rules. That is almost a new thread topic "Music's New Rules" - one example would be "how many different forms of the blues scale exist and when do you use each one?" - another would be "chord substitutions for accompanying a melody".

Also - just to note that this "mystery" of the "blue note" is not just in my mind. It has tripped up deeper thinking musical theoreticians than myself. Here is an article where the author starts to dig into the specific topic, but while he finished the web site, never finished his article about the "blue note": ("Examples coming soon." he left it saying)

http://legacy.earlham.edu/~tobeyfo/musictheory/Book1/FFH1_CH3/3L_TheBlues.html

And when it comes to rules, consider just page ONE of the same person's book #2:

http://legacy.earlham.edu/~tobeyfo/musictheory/Book2/FFH2_CH3/3A_ChordVoicingDoubling.html

[examples of his rules below]



And more rules:

Thing is, different rules apply to different genres (and styles and periods) of music. That's really how we define different types of music in the first place.
So, with Bach chorales, they sounded the way they did because of how they were put together. There are rules for that - some more flexible than others, maybe, but definitely things you should do, and some other things you should not. You study the rules in such detail because it is such an old form of music, so distant from modern culture. We can't be instinctive about what's right and wrong there, because we're so used to the very different sounds of modern music. (We could easily write a harmony which sounded fine to our ears, but would be wrong for that period.)

With modern types of music, which feel more central to our culture, we can often pick up the rules well enough intuitively, because we've done so much listening that we've absorbed the basic grammar. We're more sure of what sounds right and what doesn't, even if we don't quite know how to get the right sounds reliably.

Still, all types of music have their own sets of rules, this is the point. There is not one central body of "Music Theory" that can be applied to everything (not even to all western music).

Blues sounds the way it does because blues musicians do certain things, and don't do other things.
There may be a few practices they have in common with Bach - or classical theory, or jazz theory - but the point is blues has its own set of practices, and if you want to play blues - and have it sound like blues - you have to know what they are.

Same with jazz, or rock'n'roll, bluegrass, etc....

The trick is to know - for whatever type of music you want to make - which rules are fixed (break those and you will sound like an idiot), and which have a built-in flexibility. Follow the latter kind too closely, you will sound unimaginative, as if you've learned it all from a book.

All blues musicians have something in common, but they all sound different too. We have to learn what it is they have in common (that makes their music "sound like blues"), and what it is they don't, which is the space we have for sounding like ourselves.

To put it another way, there is material we are given, and then there is the stuff we make out of it. That material is different from genre to genre; and the freedom we have to make new stuff with it can also vary from genre to genre: the amount of freedom a musician is deemed to have (to deviate from a composition), and the ways in which they may deviate.
Improvisation is different in baroque music, dixieland jazz, bebop, blues, celtic folk, Indian raga....
So there are rules for the process, as well as for the information.

 

[amstrtatnut]

In blues I have notes that I use and notes I land on. I rarely just land on a b5. But I use it all the time as a passing note.

Just a hammer on pull of from 4 to b5 to 4 sounds waaay bluesier than hammer on from 4 to 5 and back to 4.

Call it what ya wanna so you can file it in the tool box.

 

[Mark Robinson]

Any note held to analysis will be found out, maybe found wanting? It's phrases that matter. It's a forest or the trees thing. It's the whole mood of the music. When I'm steering and thinking about notes by name or number, my playing is stinking! For any given setting there's usually at least one and possibly two avoid notes at the most, for a fluid player. The hard part is playing simple melodic phrases that are not boiler plate licks. I can't even consider fast playing. I really admire folks who pare it down here and there, and then paint behind that pared down approach with startling harmony. Frisell comes to mind.

I think that some of the hand wringing about what's blue and what's not rolls back to piano players and organ players who can't bend and have to mine those half steps with great touch to get the juice into their playing. Vocalists and guitarists and other more elastic instruments don't need to organize those tricks the same way.

 

[kimock]

We're clearly using the same words to mean different things here.
If a sung note is not fixed, then surely it moves around (or is capable of moving anyway). If it doesn't, that means it's fixed.
Yes? No? Help me out here....

Sorry for the confusion and the delay, I was busy. .

I'm thinking you haven't "fixed" a pitch until you physically commit it to a tuning or temperament.
Figure out in advance what that right note is and build it into an instrument, tune the string, cut a fret slot, etc., but take it out of the normal vocal world of a musical note being a gesture with a beginning, some contour thru the middle, and an end point.

Right?
You're fixed at the point you're doing the connect the dots 12 tone thing because you can't connect the pitches directly.

So, back to vocalized blu third. .
If it's a recognizable sound and function in some area of the octave bordered by other recognizable sounds and functions and you don't pin it to a single frequency it's naturally going to have that "swooping in and out" vocal contour because that's what voices and variable pitched instruments do.

Or you could just pick some mid-way value, tune it in advance, commit it to a key on your keyboard and bingo: you've got a fixed 1/4 tone in between your major and minor thirds.
That's the same way we dealt with our swoopingly expressive major and minor vocalizations, we just eliminated any possibility of contour or shape between them by tuning them in advance.

Functionally, the quarter tone/neutral/blu third is part of the 7th partial family of sounds by virtue of its obvious utility in circumventing the major/minor system which is kinda the whole point of the blues thing; not "both major and minor", but "neither major nor minor".

You can let that "blu third" meaning/function float, same as any other note, by playing it on any variable pitched instrument or singing it, or you can pin it down and tune it in advance just like any other note you'd commit to a keyboard.

Right?
It's fixed if you fix it, same as anything else, and it exists as contour or shape connecting seamlessly to other melodic contours and shapes if you don't.
Same as everything else.

That doesn't mean it "moves around" as a functional pitch area in the octave if it's not fixed, it just means it can't be used with any melodic contour or shape if you DO fix it.
All the notes are like that. .

Depends where you're coming from culturally with your listening mostly I guess.
Some folks are used to piano music and the stuff in the cracks is a mystery, half heard, some folks hear, teach, execute, recognize, seven versions of the tonic.

Again, I get where you're coming from and think it's fine for you to use the "notes move around" language from that perspective.
Just dig it might be more a matter of low pitch resolution from the 12 tone fixed pitch instrument perspective than a lack of specificity or intent on the part of the singer or player who would be resolving smaller intervals than half steps.

 

[Motterpaul]

Just a couple post-scripts:

1) a fixed-pitch note is one where the fundamental frequency is all you hear and it does not change. Pianos can only play fixed pitches (sad for them, I find it very limiting). Guitars can really only play the fundamental note and sharp (vibrato) technically. However, a guitarist can bend up to a note (minor to M3, for ex) and then let it go lower. Saxes can bend notes fairly easily. Violins & voices are most flexible.

2) I read someplace that one difference between classical music and "blues" is the fact that the blues doesn't mind unresolved dominant 7th chords (i7, IV7). I think this is a very good beginning to modern harmony.

3) no one is taking the note away. All I said was "overblown" in importance (or I could have said reputation)

4) in terms of "avoid" notes... who here doesn't know Miles' "In a Silent Way" where he lays down the blues scale starting at 04:12. He starts with a m3, riffs around the b5, hangs on the P4 (i love it) longer than most notes, and in under a minute (4:55) is already on a minor 2nd (or flat 9) which many would probably define as an "avoid" note - but he really sets it up.



Most of the bass line is based on a Maj3, going up to a #9. The background chords (elec piano) alternate between maj1 and min1 chords. To me, this is like "the bible" of modern melodic voice leading, in terms of playing over a simple, singular dom7 chord and using all the "blue" notes.

 

[kimock]

Guitars can really only play the fundamental note and sharp (vibrato) technically. However, a guitarist can bend up to a note (minor to M3, for ex) and then let it go lower.

Fretted guitar doesn't have the 100% flexible thing going on, but you can bend flat to varying degrees in the higher register on the wound strings.
One half step up or down from the fret in some cases.

And there are plenty of electric guitars out there with mechanical vibrato that'll raise and lower a lot or a little, so while there may be some general truth to the "sharp only" observation, guitars these days will play sharp and/or flat from the fret and/or nut.
Just depends on the guitar and who's playing it.

 

[Motterpaul]

and with that you can have the last word - oops.