Hi, for example in "D Dorian scale" video there are "b3" "b7" notes. And my question is why do you call those notes b3 b7?
b is used for "flat" because it looks like the flat symbol, and # is used for sharp notes for the same reason.
#5 = sharp fifth
b3 = flat third
Bbm = B flat minor
D#M = D sharp major
Hello. They call them that because it is a flat 3 and a flat 7 in the scale. The b is how they write a flatted note in music. b3 b5 b7 for example is flat 3 flat 5 and flat 7. Take any root note and play a major 3rd up from it. Then play the note a half step below. That is your minor 3rd or b3. Hope that helps.
The D Major scale is D E F# G A B C# D = R M2 M3 4 5 M6 M7 R.
The D Dorian scale is D E F G A B C D = R M2 b3 4 5 M6 b7 R.
So, the Dorian scale is like the Major scale, but with b3 and b7.