Technical room in the attic, problems with soundproofing?

A little anecdote about this: The founder and owner of a company that builds fuel cells installed a fuel cell from his own production in his own house. And for some reason, it seems that a certain resonance frequency was hit, causing a strong humming to spread throughout the entire house. No idea if that was ever resolved.

Otherwise, decoupling is good and correct; it helps control structure-borne noise, and airborne noise is blocked by as much mass as possible, for example an enclosure made of heavy material. This can also be a combination of OSB boards and mineral insulation.

You can achieve a sound insulation rating of 70 dB between two cinema halls purely through lightweight construction (gypsum board on stud framing with mineral filling). So all of this is doable.

Is it now a confirmed finding that controlled residential ventilation in all its aspects does not become a collection point for all kinds of dirt? That is, that not only the central unit but all the ductwork remain clean and uncontaminated in the long term?

Is it now a proven fact that a controlled residential ventilation system does not become a collection point for all kinds of filth in all its areas? In other words, that not only the central unit but all ductwork remain clean and uncontaminated in the long term?

It depends on the design and execution. What is certain is that a controlled residential ventilation system brings significantly cleaner air into the house than an open window, as the air at least passes through a coarse filter and possibly a heat exchanger. This pre-treatment is, of course, completely missing with manual window ventilation, and everything flying around outside enters the house unimpeded.

I can go along with that so far. But what happens to particles that we exhale inside the house, whether with or without Corona? What accumulates long-term on the walls of the pipes?

It is exhaust air and only of secondary interest, as it does not come into contact/mix with the supply air at any point and everything is discharged directly outside. (Except for rotary heat exchangers).

But filters on the exhaust air valves also help here.

Here as an example, supply air valve in the living room, approx. 9 years in operation. No cleaning in all those years.
Visual impression. Looks like it was installed yesterday.

I need to take a closer look at the topic of [Kontrollierte-Wohnraumlüftung]. Basically, it's good to always have fresh air and at the same time not lose too much heat in winter. There will surely be microbiological studies on that as well.

There will certainly be greater dangers in the bathroom, toilet, and kitchen than from the ventilation system. There are also areas behind cabinets and boxed-in sections that haven't been cleaned for decades.

If you look at the dirt in the filters, you'll be glad you didn't inhale it.

Oh, how I would have loved to have a controlled residential ventilation system.