The place I currently find myself in must be a public facility used for temporarily storing bodies; the sounds from outside the coffin likely belong to the caretaker of this establishment.
That caretaker seems experienced, referring to the disturbance inside the coffin as the "Restless One" phenomenon, and engaging in conversation with a clear and composed mind, not showing any signs of panic throughout the exchange.
The body I currently inhabit appears to be that of a miner, with the cause of death being a fall from a great height, resulting in severe physical injuries.
As Duncan conversed with the voice outside the coffin, he silently gathered this useful information while further confirming his current body's unsuitability for his purposes.