Tomo Fujita Guitar Wisdom

I have a question about the D blues bending exercise video. At 01:15, Tomo introduced 4 notes for the IV chord:

A. B. D F
9 M3 5. b7

As far as I understand, It is G chord. My question is why A note is called 9? not 2?

The second and the ninth are the same note. The 9th is just an octave higher. Same with the 4th and the 11th. And the 6th and the 13th.

Hope that helps

Thanks for the quick reply.

I can understand 9th is an octave higher than 2nd. Then the next question will be why it takes the G note with an octave lower as a reference?

Also, If A note is called 9th becase it is an octave higher, then should we call A B D F as 9 10 12 b14 instead? I am wondering if there is any particular reason why A note is called 9th in the video.

I've never found the "octave higher" rule to a very strict rule when it comes to guitar. You'd never call all the Fs in an F barre chord root, 8th, 16th, for instance.

The rule of thumb that I use is that if there is a major or minor third anywhere in the chord, then any time you add a second or a fourth, you call it 9th or 11th. If there is no third you then call it a sus 2 or sus 4.

For this lesson, its just a way of naming the note in relation to the chord that you changed to, i.e. the 4 chord. It's not meant to denote a specific place in the octave relative to some root position.