Mechanical / HVAC Hum Loop 2

A second looping machine hum from rubberduck's CC0 SFX pack, for layering plant-room, elevator-machinery or HVAC ambience. Redistributed via the CC0-Public-Domain-Sounds repository. Software: Audio (ambient/walkthrough). Author: rubberduck. Licence: CC0-1.0. Source: https://opengameart.org/content/100-cc0-sfx-2