How could I write down slap bass (slap and pop) on sheet music?
The standard way to do notate slaps and pops is to use a letter above or below the note to specify the technique and a standard or "x" note head to specify whether the note is sounded or muted.
Different sources adhere to different standards regarding the letters used to indicate slap, but it's usally "S" or "T". Pops are indicated by "P". There is typically a legend that explains the notation.
- the website Ultimate Guitar uses
Sfor "slap" and
- the publisher Hal Leonard uses
T("thumb") for "slap" and
- Berklee Online also uses
Pfor "slap" and "pop" ("pull"), respectively.
So a simple slap/pop bass figure might look something like:
The above example would mean to
- Slap the open E string, and let it ring
- Slap and mute the open E string
- Pop the 7th fret D on the G string
I've seen an "X" note head. Once I saw "snap" written (like pizz or arco).
This page has a bit more. https://www.artofslapbass.com/adam-booker-slap-bass-notation/