Electro motor sound too loud?

[nazaka]

Hello, i have some question to the sound when i running in electro mode.

When i'm submerged and i go very slow, the electro motor make a lot of noise. I can use the hydrophone, but it's very difficult with the back sound.

My first question is if it's realistic?
And my second, why in SH3 we don't have this issue?

Thanks for your answers