Definition I found for Instrumental: 'An instrumental or instrumental song is music normally without any vocals, although it might include some inarticulate vocals, such as shouted backup vocals ...'
So a primal scream expressing emotion or a word or two is acceptable if not overdone.
Some artists have included notes describing the inspiration for their songs.
The artists' notes can be seen in a new tab.
Peter Morley Has 3 entries in the Best Original Instrumental Category, from his Ambient Cafe series.
View artist's notes.
Song I1 Peter Morley: 'Bright Shiny Thing'
Song I2 Peter Morley: 'Upside'
Song I3 Peter Morley: 'Night Owl'
Steve Frawley Has entered his instrumental, Water.
Song I4 Water
Song I5 Von Spriggan 'Boss Fight'.
Described on Spotify as 'Music to kill bosses to'! View on Spotify
Song I6 Billy Neal 'Something She Said'
View artist's notes.
Here is 'Something She Said'
Song I7 The Milkmen. 'Hidden Song'