[vac4873]

OK, I can't stand it...I don't post very often here, but this discussion is too interesting not to throw my 2 cents into.

I think the number of posts and differing interpretations supports Brian T's assertion that the "2" designation (Bb2 or A2 or whatever) is ambiguous.

Here's my take: a suspended chord implies that the composer has chosen not to expose the major or minor tonality of the chord. This means that the 3rd scale degree (in the case of Bb, "D", in the case of A, "C#) will not be played. Ironically, this adds a certain "ambiguity" to the chord.

An add 9 includes both the 2nd and 3rd scale degrees to the chord. As Larry mentioned, technically the 2nd degree should be voiced abovethe third for the chord to officially be an add 9, but modern ears have become accustomed to hearing it clustered right in between the tonic and the third, and if you have a bass player it technically is an octave above the fundamental 3rd.

The 9th means, at least to us "old schoolers", that we are playing a dominant 7th chord with the second scale degree inserted in the octave above the (flatted) seventh, hence the James Brown/ horn shout inferences.

As far as practical application, this rule of thumb seems to work for me:
If the chord is being substituted for a minor chord, always leave the third out, if it is being substituted for a major chord, it doesn't really matter, exception: if you are doing a "voice leading" progression, it should mirror whatever its context implies.

Examples: I'm going to use two variants of a very common modern progression that I've seen notated with the "2" designation. I probably know between 25 and 50 worship songs alone that use this formula, and at least that many other modern songs that employ it.

Progression: C G A2 F - Don't play the third. This is a variant (in different keys) used recently.

Progression: G D(sus4) Em C2 - this is another more common variant on the same progression in another key. Most players finger this 3-2-0-0-3-3, x-x-0-2-3-2 or (3), 0-2-2-0-3-3 (technically an Em7), x-3-2-0-3-3. In this case, the C being played is actually a C add 9. The fingering for C sus 2 would be x-3-0-0-3-3. However, if you play this progression both ways and listen carefully, you will find that when you play the sus 2, there seems to be something missing (at least to my ear - your results may vary). This is because the "E" which is the major third in the C chord has a voice leading that implies some finality and a "hankering" to return to the D which is in the G chord. Try it.

The bottom line for me is the rule is the same for reading it as applies to any other reading --- context, context, context.

Matt