Jazz Blues With Voice Leading

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I apologise if this is the wrong place to ask this, but I have been trying to use what I am learning from the theory course to analyse what I am playing.

In bar 1, in the notation, the Bb13 and B#5 the b7 is shown as a #6 (i.e. G#) rather than b7 (Ab). A similar thing happens in bar 2, where the b7 (Db) in the Eb9 and Eb13 are shown in the notation as #6 (C#).

I understand that #6 and b7 sound the same, but I am wondering if there is a reason for the way they appear in the notation or if it something that will become clearer as I progress with the theory.

Thanks

You’ll find that notation of accidentals can vary depending on who (or what – sometimes it’s automated software that chooses between a sharp or flat) engraved the score. I’m not sure that there’s an “official” answer.

People take different approaches. Often, they’ll stick to uniformity with the key signature, so that in a key signature with flats accidentals are flat and in a key signature with sharps accidentals are sharp. Sometimes they’ll select sharp or flat (possibly arbitrarily) and stick with it consistently in the score. Also common is using a sharp if the musical motion is ascending, and a flat if it’s descending. I imagine there are other schemes.

Personally, I like notating accidentals based off the note position in the circle of fifths, keeping the note names of the accidentals as close to the diatonic notes as possible. For example, here’s the notes of the circle with the diatonic notes of the key of B♭ highlighted in bold:

F♭ C♭ G♭ D♭ A♭ E♭ B♭ F C G D A E B F♯ C♯ G♯ D♯ A♯ E♯ B♯

If I’m in the key of B♭ and I want to specify a note which could be A♭ or G#, I’ll look to see which one is closest to those highlighted/diatonic notes in the circle of fifths. In this case, A♭ is one spot away, while G# is 5 spots away. So I would choose A♭ as my accidental. Also, note that B♭13 has a G natural in it (i.e., the 13), so also having a G♯ at the same time seems weird to me, and A♭ is the minor seventh in the key of B♭, so it’s very common as part of dominant 7th and extended chords. (My answer to this differs from the lesson’s score, but as I mentioned, I’m not sure there’s an “official” answer. If someone knows otherwise, I’d be interested to know.)