Is there a more specific term for this blues sound? (5 and ♯4)

Question

I like the crunchy, janky texture of playing a note with the note a semitone under it in a melodic voice, usually on the dominant scale degree. For example, in the original Thomas the Tank Engine TV show theme's intro.

---------E♭-E♭------E♭-----E♭-E♭

---A♭---D--D----E♭----A♭-D---D

Is there a name for this? I can't find one.

Edit: Sorry, I should have been more clear. I'm advanced enough at theory to know my specific intervals; I know it's a minor second. I'm looking for a more specific term to describe the texture/effect of using minor seconds in the melody. Looking for more of a blues term than a theory term.

Answer 1

There are a couple of things going on there. The Ab-D gives you a tritone, and you might think of this as a Lydian sound. But what you are probably more interested in is the D-Eb dyad. That interval is a minor second. I don't know of any name for that other than minor second, but it is a sound that was used a lot by the great jazz pianist Thelonious Monk. It is a great sound, and you can often bring it out in voicings of Maj7 chords, Lydian chords, or altered chords.

Minor seconds can be used to provide very pretty, but somewhat astringent, shimmering sounds. In the case in question, the already angular tritone movement from Ab to D is underlined by the astringent quality of the minor second dyad D-Eb. It is the combination of these two devices that results in the "janky texture" that you describe.

Answer 2

Yes - it's called a minor second if they are in the same octave, and a flat nine if they aren't. It's a pretty dissonant interval - in your example I think it's an effort to mimic a train whistle.

To find the name of any interval, count the number of letters between them, beginning with "one" as the number for the lower pitch; ignore any sharps or flats. Then compare the upper note with the major scale of the lower one...

if the upper note is the tonic, fourth, or fifth of the lower note's major scale:

• it's perfect if it's in the scale
• it's augmented if it's as half step above the scale tone
• it's diminished if it's a half step below the scale tone

if the upper note is the 2nd, 3rd, 6th or 7th of the lower note's major scale

• it's major if it's in the scale

• it's minor if it's a half step below the scale tone

• it's augmented if it's a half step above the scale tone

• it's diminished if it's a whole step below the scale tone

you can also have doubly-augmented or doubly-diminished intervals, like C-Fx or C#-Gb