I mean , for instance , you 're  you 're talking about the signal and noise , um , at a particular point. And even if something is sort of stationary in ster terms of statistics , there 's no guarantee that any particular instantiation or piece of it is exactly a particular number or bounded by a particular range.
Mm - hmm.
So , you 're figuring out from some chunk of  of  of the signal what you think the noise is. Then you 're subtracting that from another chunk ,
Mm - hmm.