[st. Nougat]

I am looking to see if anyone has reliable knowledge on how these devices operate?

The rules state: "This device creates a field of random noise..."

My questions, to the people within the room, does it sound like a TV has been turned to static or does it function some other way?

[All4BigGuns]

I believe the noise is such that it is above the range of human hearing, but recording devices still pick it up.

[st. Nougat]

But if it is operating in ultrasonic frequencies then it's not truly white noise (which is random noise and should cover all frequencies) and it would be easy for a listening device with a select sound filter to easily filter out any sound over X hertz

[Novocrane]

If you want unobtrusive random noise, take the Babbler from Spy Games.

Think of it in terms of being in a restaurant and not being able to make out the conversation in the booth behind you. That is the babbler. Because it presents the background noise surveillance crews are expecting to hear, it is less conspicuous than the white noise generator.

[Aryeonos]

A white noise generator is just a little cylinder with a motor running inside that makes a low whirring noise, they use these in therapist offices all the time so each room's conversations remain private. It sounds like whirring or snow on TV, but it's rather soft.

[Xzylvador]

Could it be used to assist infiltration or is the effect obvious?
eg: Dr. McNinja is sneaking up behind two guards and rolls 3 hits on infiltration. The guards have a dicepool of 7 perception. Could Dr. McNinja reduce their dicepool to a single die by activating a white noise generator or would the guards immediately know they're suddenly inside the 'field' of a white noise generator?

[Aryeonos]

Depends on if Dr. McNinja drank a full bottle of tequila before hand. But no, the white noise generator is subtle but still obvious, like a floor buffer being heard from the other side of a building or something. It's used to make a conversation private, so you could have a muffled conversation without your words being discerned behind closed doors, with the white noise generator outside (Probably inside instead, but I've always seen them set outside.) People outside would most likely know a conversation is going on inside, but the already muffled words would be further  indiscernible by the white noise generator.

If you talked low, and had the generator running, people might not even know you're talking inside over the monotonous noise of the generator. It's just a privacy screen that works for sound really, it's obscuring but a directional mic and some software could defeat it easily.

[Mirikon]

A white noise generator and a babbler both work by 'masking' conversation. However, the method in which they do it is different. The white noise generator is essentially the same as the time honored tricks of turning up the radio or running the shower in order to defeat listening devices. In other words, it creates other noise to overwhelm quiet conversation, but it is quite obvious that there is other noise. The babbler, on the other hand, functions by creating similar noises, and camouflaging the conversation in question. To put it another way, a white noise generator is like finding a needle in a haystack, while a babbler is like finding a particular tree in a forest. Both can be quite difficult, but in different ways.

[Shaidar]

Click for an example of White Noise.