Noise on starships

[Winston Blake]

I know this thread is about criticism rather than rationalisation, but i'll have a go at it. Reading over this quote a few minutes ago, i realised it says nothing about the nacelles, power system, engine, etc.

A beat as Picard listens to the sound of his ship, raises
an eyebrow... we hear nothing... he moves forward to
La Forge and Perim...

PICARD
When was the last time we aligned
our torque sensors...

PERIM
Two months ago, sir...

PICARD
They don't sound right.

La Forge and Perim react, work the controls, exchange a
look at the results...

LA FORGE
The torque sensors are out of
alignment... by twelve microns...
you could hear that?

PICARD
(pleased with himself)
When I was an ensign, I could
detect a three-micron mis-
alignment...

So really, the power system could produce negligible noise, Picard's observations could be purely due to the bridge's unique equipment and the background noise could be completely independent of both. Except that following up this:

In DS9, the ancient Bajoran ship that Sisko pilots has no background noise. Sisko even makes a point of it, saying that there's no engine sound like on a starship.
Seeing as this ship obviously had life support and gravity generation then those can be ruled out.

led me to this:

Sisko settles onto the floor, his back against the wall,
lets out a contented breath. Jake settles onto the floor
nearby. After a quiet moment...

SISKO
Listen...

Jake cocks his ear for a moment...

JAKE
I don't hear anything...

SISKO
Exactly... not even the hum of an
engine...

Sisko smiles to himself, caught up for a moment in the romance
of sailing...

So the background hum must be caused by a ship's engine. The power distribution system is a prime suspect since it's ubiquitous and linked to the reactor. However as vivftp was shown, the EPS conduits making the same noise everywhere Does Not Make Sense.

So here's my idea: cooling for distribution substations. Instead of a few big ones feeding several rooms each from the main supply, we could have lots of small ones, so you have one 'EPS regulator' per room. Since it's managing superheated plasma, you stick a heat sink and rumbling cooling fan on it (or maybe have a small pump run liquid coolant around it). Every heat sink can have the same cooling rate (and hence noise) as long as the hottest ones stay under a nominal temperature. Anyway the point is, you get a noise-producing system that's independent of how much strain the EPS conduit is under, is a necessary part of the ship's functions and is ubiquitous throughout the entire ship, since every room has a regulator under the floor (or somewhere).