2 note chords?

Pretty simple, really... it's a matter of historic evolution.

Music started out monophonic - just a melody line. You might have a whole chorus of voices, but if they're all in unison, it's still the same thing, and it was called melody.

Then you get two voices doing different things, and they interact. We needed a way to analyze what was going on, and the basis of that was the distance between the two voices - the interval between them, so the space between any two different voices is an interval (no matter how many voices are on each note). People started thinking about intervals about a thousand years ago, long before they played chords.

Then we add a third voice... and the result needed a name. Chord was chosen, so three different notes are a chord.

We didn't really stretch beyond three different voices until about 500 years ago, and when we did start, it was with dominant 7ths. Since it was just a little abberation theoretically, we came up with chord extensions to 7ths.

More complex chords have only been around for 100 years or so, and the chord format (having already been stretched from three voices to four) was just expanded to deal with the new material.

Your professors are looking at music from an analytical standpoint - two voices can only be analyzed one way, by the distance between them. It's true that intervals can function as chords do, but it's still easiest to see them as just two notes.

Guitarists have myopia in the other direction - if you can finger it, it's a chord. We create things like 'power chords' that are completely unknown to other instruments - pianists never talk about them, even though they're quite capable of playing intervals in octaves, which is all a power chord is.

In order to talk about music with people who play other instruments, it's important that we have a common language. Since 'power chords' are specific to the guitar, if you insist they're chords, you'll be fine with many guitarists, but you won't be able to communicate the idea to folks who play other instruments.

Picture it the other way... a flute can produce a harmonic. They call it overblowing. Even though the effect is the same (an octave above what's fingered), it would be kind of silly to talk about overblowing a guitar...so it's best to use the common denominators.

pianists never talk about them, even though they're quite capable of playing intervals in octaves, which is all a power chord is.

Umm, most powerchords are 5ths, not octaves.

Otherwise I agree with every word you wrote.

pretty much what the wizard said then...

2 notes.. is an interval, of a pefect 5th you were talking about Snoogy.

chord is 3+

Umm, most powerchords are 5ths, not octaves.

Powerchords can also be fourths.... what I said was that pianists are quite capable of playing intervals in octaves, like this on the guitar:

-x-
-x-
-x-
-5-
-5-
-3-

You have both an interval and an octave. Since you need three notes to make a chord, a pianist wouldn't consider two notes a chord.... but they won't consider intervals repeated at the octave a chord either, no matter how many keys they're playing.

Of course.

Powerchords can also be fourths.... That's just a different way of looking at it. If you're doing your "power chord" with the fifth below the root it looks like a fourth.

When I was at school my music teacher said:
1)music is sound and silence
2)chords or 2 or more notes played simultaneously

When I went to University my music professor agreed and disagreed.

My advice is if it makes sense to call 2 notes a chord do, don't listen to other people to much, especially me :D

What about an Em or a D6? Both are valid "chords". But you only fret two notes. Wouldn't the third just be one of the open strings?

Em has 3 notes (E-G-B, 1-b3-5). Even though you only "fret" 2, you play 6 notes, 4 of them on open strings. Some are repeated.

In the usual fingering (0-2-2-0-0-0), Em is E-B-E-G-B-E.

D6 (D-F#-A-E, 1-3-5-6) in a common open fingering (x-x-0-2-0-2) is x-x-D-A-B-F# with no repeated notes, although you could play the 5th and 6th strings to add an extra A (5th) and E(6th).

If you're doing your "power chord" with the fifth below the root it looks like a fourth.

They're inversions of each other. Convention is to count an interval up from the lowest note... even though it's down a fifth, it would be identified as a fourth.

There are plenty of tunes, like "Smoke on the Water" that are played with double stops, and it's clear from the vocal melody that the root notes are the upper ones - the line is harmonized a fifth below. But if we call them 'root five power chords' (which I've seen), we're just complicating things even further. I think guitarists would be better off learing the proper terms for things, rather than trying to invent a separate guitar theory... for one thing, it allows us to learn from books written about other instruments, and there's good stuff there.

Example: your phrasing will probably improve if you read an improvisation book written for trumpet or sax. They have to deal with where to breathe, which means their solos need to be designed around pauses - and pauses in the right places will improve many a guitar solo.

There are plenty of tunes, like "Smoke on the Water" that are played with double stops, and it's clear from the vocal melody that the root notes are the upper ones - the line is harmonized a fifth below. But if we call them 'root five power chords' (which I've seen), we're just complicating things even further. I think guitarists would be better off learing the proper terms for things, rather than trying to invent a separate guitar theory... I disagree. In the context the upper note is clearly the root. Insisting on a "proper" convention naming the interval from the lowest note needlessly complicates understanding the use of inverted power chords. When "real" chords are inverted we may note the fact but still name them as the basic chord without inventing some fanciful name to describe the chord using the lowest note as the root. We just consider it a different voicing of the basic chord. And that's exactly how we hear an inverted power chord. The tonality of it stays with the root, even when it's on top. It simply doesn't make sense to talk about fourth intervals.

When "real" chords are inverted we may note the fact but still name them as the basic chord without inventing some fanciful name to describe the chord using the lowest note as the root

But that's exactly the reason for the naming conventions - we'd need to rename some chords! For example, Am7 played in first inversion is C-E-G-A... which is C6. Considering the inversion, of a chord or an interval, can change its name beyond the harmonic intent - it would make analysis of one piece of music against another pretty darn difficult.

In the case of the fourth vs. fifth, you can chart it out as fifths, and you can play it that way or inverted... but if you show a transcription to anyone, it'll be a fourth - you read intervals up from the bottom. If you could do it either way, you couldn't tell a minor third from a major 6th - just like the Am7-C6 above.

Doing it your way would obscure the key and harmonic structure of a song by changing the names, therefore scale degree, of the "chords." It's confusing.

As for chords, they often are ambiguous and can validly be given different names. The proper one to use depends on the context. Not altogether different from calling the same note A# or Bb depending on how it's used.

It's not confusing at all - since a chord structure contains 1-3-5, and a 'power chord' leaves out the 3rd, you have the 1 and 5 from the scale. If you're in C (easy enough to see from the key signature when you read the music), those notes will be C and G.

If G is on the bottom, it's a perfect fourth. If C is on the bottom, it's a perfect fifth. These can be identified in a glance - if it's a fifth, both notes will be on spaces (or lines), and if it's a fourth you have one of each.

Perfect intervals won't have any effect on the harmonic analysis of the piece - they're perfect to begin with because either note is in the key of the other, so it doesn't gum up the works on that account. You'll identify the root movement (which doesn't have to be the bass), and recognize the inverted interval as 'fifth in the bass'... while still calling it a perfect fourth.

I'm not advocating changing chord names at all, in any way. If a song harmonically calls for a C6, then it should be a C6, even if the 'top' note is in the bass. I'm saying that the naming conventions are widely used, on many instruments, and to use something different because we play guitar and it makes 'sense' to do it that way means we can't communicate effectively with others. It's bad enough that we make up terms like power chords... if we start telling keyboard players to 'just play it in fifths' when we mean fourths, we're in trouble!