oompahing

/ˈumˌpɑɪŋ/
verb
  1. Present participle of oompah: the act of playing or producing a rhythmic bass sound, like a tuba in polka music.
    • Oompahing along with the beat, the musician kept the dancers moving.
    • The tuba player was oompahing loudly during the song.
    • We could hear the band oompahing from across the park.