Williams at Linear Technology has written several application notes which
discuss the practical measurement of noise. Search on their website for a
PDF entitled "Characterization of Noise in Low Dropout Regulators" -- not
that you are measuring an LDO, but the techniques should be valid.

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...
I need to measure the "equivalent noise voltage", in units of
nV/square root( hz) of a JFETs drain-source at a given Vds & Ids and
F=10 hz. How do I do that? What's throwing me is the F=10 Hz. What do
I do with that? I thought to take the measurement, I would bias the
FET to the required Vds and Ids and measure the voltage across the
drain - source with an RMS meter. Then divide that by the sqrt of the
bandwidth of the RMS meter. I've Googled, but didn't find anything to
straighten me out. Any help?