ᐅ How soundproof are windows?

Hello everyone,
since moving into our house, we have had a lot of issues with the windows. They are aluminum windows with triple glazing. I keep noticing how sound-transmitting they are. For example, this morning I woke up and heard the birds singing. That’s not really a problem, but it surprises me considering the window was closed and there is no tree nearby. Also, when I stand at the window on the first floor (second floor in US terms) with it closed, I can hear the neighbors talking in the garden next door (it’s a terraced house, so not very far away). They are not shouting. Is this normal, or am I just expecting too much?

The windows are soundproofed according to the specifications ordered. If nothing extra was requested, then they have the lowest level of sound insulation, meaning you can hear everything.

We also have windows without special soundproofing requirements, and through them, I can neither hear people talking nor birds. Maybe have them properly adjusted?

We have triple-glazed PVC windows without additional sound insulation. Loud vehicles and mopeds are audible, passing cars barely so. Birds or voices are not noticeable to me.

Well, it depends on who the manufacturer is. For one, the minimum standard is like this, for another, it is different.

It’s like comparing cars: "mine is faster" without knowing which car you’re actually talking about.

I also fear that the windows were not ordered with high sound insulation. Additionally, we know of at least one window that has not been properly adjusted. That’s why we have been dealing with the builder for almost three years now. The windows were custom-made by a metal construction company. Unfortunately, I can’t find any information about the quality in our documents.
But it’s good to know that it can be done differently for the next house.