That's a good way of looking at it. The "unnoticeable" part is where more can be teased out: That is, to expect a specification for the desired S/N (signal-to

That's a good way of looking at it. The "unnoticeable" part is where more can be teased out: That is, to expect a specification for the desired S/N (signal-to-noise) ratio and bandwidth, and/or bit rate at which the downstream algorithm is expected to work. This doesn't have to be a perfect estimate/evaluation/measurement, but it helps to get the ballpark amount of computation power, delay, etc. needed to actually make the system work. All too often I see people react to a noisy signal, by "putting a filter on it," without knowing how much attenuation/gain/phase shift, etc. are actually needed to make the system work acceptably. E.g. You don't want to spend too long designing the perfect filter... And you want to know if there's any hope at all cleaning up the signal to make use of it! Good luck with your filtering projects!