Infinite flight intentionally specifically made the sounds of the new reworked b757-200 to be asmr inducing, and relaxing. This is to help it's pilot cope with the long flight times in long haul flights.
The sound are meant to be heard when the throttle of engine 1, and engine 2 is at a certain percentage. For example, the takeoff throttle for the b757-200 in infinite flight is 70-75%, and the healthy cruise throttle for engine 1, and engine 2 is 67-71% throttle. In this video, the throttles are at 70%. That way, the engines sound more tingle inducing. Sometimes, I fall asleep to the sounds of the engines at cruise.