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.