[thecosmicfrog]

You mean the "whale song"? It's just a quirk of the Pratt and Whitney PW1000G series at low power settings. The same engine family is fitted to new Airbus A320neos and makes the same sound. Examples:

https://youtu.be/Eeq4rYQUozY

[usr1106]

Ah, I didn't know it's called whale song, but yes that's what I mean. Low power setting might be correct, I think you hear that typically in approach phase. I have been flying with many types planes from Vickers propeller, Caravelle, 727, L-1011, 717 and its predecessors to 747-8, A350, Dreamliner, but I never remember hearing a sound making me feel so uncomfortable. Despite the fact that the old ones were uncomfortably loud. After over 40 years of flying I nearly thought, now I can understand people suffering from flying anxiety.

Don't remember hearing it on a A320 neo, but I guess they come with 2 engine options?