Wiktionary
fold down
vb. (context transitive audio English) To downmix.
Usage examples of "fold down".
Johnson wondered if he'd fold down his index finger to give the answer, but he decorously lowered his middle finger instead, getting the message across by implication rather than overtly.
Dauzat, every few minutes worked a cumbersome crank to raise up or fold down his stanhope's hood and demonstrate its ease of convertibility on the hoof, as it were.
She even had a small chart table that would fold down, and a selection of charts, for her father had insisted she learn to navigate, even to take her own bearings.