2 Questions about Sound

From a channel Lumen includes in full: AgentJayZ, a working jet-engine overhaul technician, explains turbine engines from the shop floor: bearings, blade coatings, starters, test-cell runs, answering viewer questions with long, patient detail.

A 23-minute video from AgentJayZ's catalogue; the title names its topic.

Video by AgentJayZ, played through YouTube's embedded player.