From the article:

> Some boxes have trumpet like devices attached to the Bass Side:
> these are mainly Germanic Button Box instruments. They provide
> better impedance matching for the lower pitches, and give a
> fairly distinctive horn-like "Om-pah!" sound.

Not true. While these front bass-section openings do let the bass sound out more directly, the little metal horn-bells in the openings are decorative. The deep tuba-style sounds themselves come from extra-large bass reeds, called helicon reeds. Instruments with these reeds may or may not have the horn-bell decorations.